Tài Liệu UNIX Tiếng Việt

http://vietjack.com/unix/index.
jsp
Copyright vietjack.com
Bi hng dn v Unix/Linux
Unix l mt h iu hnh my tnh m c kh nng thc hin nhiu hot ng bi nhiu ngi
trong cng mt thi gian.
Unix c ra i nm 1969 bi Ken Thompson v Dennis Ritche ti phng th nghim AT&T Bell
Labs. Phn hng dn ny cung cp cc kin thc v Unix.
Lot bi hng dn ca chng ti da trn ngun ti liu ca: Tutorialspoint
i vi c gi
Phn hng dn ny c chun b cho ngi mi bt u hc v Unix, t gip h hiu c
cc kin thc c bn v cc lnh, Shell Scripts v cc tin ch khc ca Unix.
iu kin tin
Chng ti gi s rng bn c mt cht kin thc v H iu hnh v cc chc nng ca n. Mt
kin thc c bn v cc khi nim my tnh s cng gip bn trong vic hiu cc bi thc hnh a
dng trong phn hng dn ny.
Tng quan v Unix/Linux

Unix/Linux l g?
H iu hnh Unix l tp hp cc chng trnh m thc hin vai tr nh mt ng link gia my
tnh v ngi s dng.
Cc chng trnh my tnh phn cp cc ngun h thng v phi hp tt c cc phn bn trong
ca my tnh c gi l H iu hnh hoc kernel (ht nhn).
Nhng ngi s dng giao tip vi kernel thng qua mt chng trnh m c bit nh l shell.
Shell l mt b bin dch dng lnh, n bin dch cc lnh c nhp bi ngi s dng v
chuyn i chng thnh mt ngn ng m kernel c th hiu.
Unix/Linux c pht trin ln u tin bi mt nhm cc nhn vin AT&T ti phng th

nghim Bell Labs, gm c Ken Thompson, Dennis Ritchie, Douglas Mclloy v Joe
Ossanna.
http://vietjack.com/ Trang chia s cc bi hc online min ph
Page 1
http://vietjack.com/unix/index.jsp
C rt nhiu phin bn Unix khc nhau trn th trng. Solaris Unix, AIX, HP Unix v BSD
l mt s v d. Linux cng l mt phin bn ca Unix m l min ph.
Nhiu ngi c th s dng mt my tnh Unix cng mt lc; v th Unix c gi l h

thng a ngi dng.
Mt ngi s dng c th chy nhiu chng trnh cng mt lc; v th Unix c gi l a

nhim.
Cu trc Unix/Linux:
S di l cu trc ca mt h thng Unix:
Khi nim chnh m c thng nht trong tt c cc phin bn Unix gm 4 c s sau:
Kernel: Kernel l tri tim ca h iu hnh. N tng tc vi phn cng v hu ht nhim

v nh qun l b nh, qun l file, ln chng trnh nhim v.
Shell: Shell l mt tin ch m x l cc yu cu ca bn. Khi bn g mt lnh ti terminal

ca bn, shell phin dch lnh v gi chng trnh m bn mun. Shell s dng c php
Page 2
chun cho tt c cc lnh. C Shell, Bourne Shell v Korn Shell l nhng shell c bit n
nhiu nht v c sn trong hu ht cc phin bn Unix.
Cc lnh v cc tin ch: C rt nhiu lnh v tin ch m bn c th s dng trong cng

vic hng ngy. cp, mv, cat v grep l mt s v d ca lnh v tin ch. C trn 250
lnh tiu chun cng vi mt s lnh khc c cung cp bi phn mm th 3. Tt c cc
lnh ny i cng vi cc ty chn (chc nng) ca n.
Files v th mc: Tt c d liu trong Unix c t chc trong cc file. Tt c cc file

c t chc vo trong cc th mc. Nhng th mc ny c t chc trong mt cu trc
dng cy c gi nh l h thng file.
Khi ng h thng trong Unix/Linux

Nu bn c mt my tnh m ci t h iu hnh Unix trn , th sau n gin bn ch cn
bt khi ng h thng.
Ngay sau khi bn bt h thng, h thng bt u khi ng v cui cng n nhc bn ng nhp
vo trong h thng, m hnh ng ng nhp ny c s dng cho cc hot ng thng ngy.
ng nhp Unix/Linux
Khi bn ln u kt ni vi mt h thng Unix, bn thng nhn thy mt dng nhc nh sau:
login:
ng nhp h thng Unix/Linux:

1. Chun b sn sng ID s dng v mt khu. Lin h vi ngi qun l nu bn cha c n.
2. Nhp ID ti dng nhc ng nhp, sau nhn Enter. ID ca bn l phn bit ch hoathng, v th chc chn rng bn nhp chnh xc nh ngi qun l ch dn.
3. Nhp mt khu vo mt khu v nhn Enter. Mt khu ca bn cng phn bit kiu ch.
4. Nu bn cung cp ID v mt khu chnh xc th sau bn s c cho php vo h
thng. Bn c qua thng tin v cc thng bo m hin trn mn hnh nh hnh di y:
login : amrood
amrood's password:
Last login: Sun Jun 14 09:32:32 2009 from 62.61.164.73
Page 3
Bn s c cung cp vi mt lnh nhc (i khi c gi l lnh $) m ti bn s nhp tt c

cc lnh ca bn. V d kim tra lch, bn cn nhp lnh cal nh sau:
$ cal
June 2009
Su Mo Tu We Th Fr Sa
9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30
Thay i mt khu trong Unix/Linux

Tt c cc h iu hnh Unix u yu cu mt khu m bo cho cc d liu v file ca bn v
cng m bo an ton cho chnh h thng chng li s thm nhp ca hacker hoc cracker. Di
y l cc bc thay i mt khu:
1. bt u, son passwd ti dng nhc lnh nh hnh di.
2. Nhp mt khu c
3. Nhp mt khu mi m bn mun i. Lun lun gi cho mt khu cng phc tp cng tt
m khng ai c th on c n. Nhng chc chn rng bn nh n.
4. Bn cn xc nhn li mt khu bng cch nhp n thm ln na
$ passwd
Changing password for amrood
(current) Unix password:******
New UNIX password:*******
Retype new UNIX password:*******
passwd: all authentication tokens updated
successfully
Page 4
Ghi ch: Ti t du * vo v tr ch cho bn a im bn cn nhp mt khu c v mi. Ngoi

ra ti h thng ca bn, n s khng hin th bt c k t no khi bn g mt khu vo.
Lit k th mc v file trong Unix/Linux:

Tt c d liu trong Unix c t chc vo trong cc file. Tt c cc file c t chc vo trong
cc th mc. Nhng th mc ny c t chc vo trong mt cu trc cy c gi l h thng
file.
Bn c th s dng lnh ls lit k tt c cc file hoc th mc c trong mt th mc. Di y
l v d v cch s dng lnh ls vi ty chn -l.
$ ls -l
total 19621
drwxrwxr-x
2 amrood amrood
4096 Dec 25 09:59 uml
-rw-rw-r--
1 amrood amrood
5341 Dec 25 08:38 uml.jpg
drwxr-xr-x
2 amrood amrood
4096 Feb 15
2006 univ
drwxr-xr-x
2 root
root
4096 Dec
2007 urlspedia
-rw-r--r--
1 root
root
276480 Dec
2007 urlspedia.tar
drwxr-xr-x
8 root
root
4096 Nov 25
2007 usr
-rwxr-xr-x
1 root
root
3192 Nov 25
2007 webthumb.php
-rw-rw-r--
1 amrood amrood
20480 Nov 25
2007 webthumb.tar
-rw-rw-r--
1 amrood amrood
5654 Aug
2007 yourfile.mid
-rw-rw-r--
1 amrood amrood
166255 Aug
2007 yourfile.swf
y phn nhp bt u vi d biu din cc th mc. V d nh uml, univ v urlspedia l cc

th mc v phn cn li l file.
Bn l ai trong Unix/Linux?
Trong khi bn ng nhp vo h thng, bn c th sn lng bit : Who am I?
Cch n gin nht l tm kim bn l ai l nhp lnh whoami :
Page 5
$ whoami
amrood
Hy th n trn h thng ca mnh. Lnh ny lit k cc tn ti khon lin kt vi s ng nhp

hin ti. Bn c th th lnh whoami cng nhn thng tin v chnh mnh.
Ai ng nhp trong Unix/Linux?

i khi bn c th mun bit ai ng nhp vo my tnh trong cng thi gian.
C 3 lnh c sn gip bn nhn c thng tin ny, da trn c s bn mun bit bao nhiu v
nhng ngi s dng khc: users, who v w.
$ users
amrood bablu qadir
$ who
amrood ttyp0 Oct 8 14:10 (limbo)
bablu
ttyp2 Oct 4 09:08 (calliope)
qadir
ttyp4 Oct 8 12:09 (dent)
Bn hy th lnh w trn h thng ca bn kim tra kt qu u ra. Lnh ny s lit k mt s

thng tin lin quan ti ngi ng nhp vo trong h thng.
Thot khi chng trnh trong Unix/Linux

Khi bn kt thc phin lm vic ca mnh, bn cn thot khi chng trnh m bo rng
khng ai c th truy cp vo cc file ca bn khi h gi trang bn.
thot khi chng trnh:

1. Bn ch cn g lnh logout ti dng lnh nhc, v h thng s v sinh mi th v ngt kt
ni.
ng h thng trong Unix/Linux

Page 6
Cch ph hp nht ng h thng Unix l thng qua s dng mt trong cc lnh sau:
Lnh
Miu t
halt
ng h thng ngay lp tc.

ng h thng s dng script c xc nh trc ng b v v sinh
init 0
h thng trc khi shutdown.

Khi ng li h thng bng cch ng h thng ngay lp tc v sau
init 6
bt u li nh lc trc khi ng
poweroff
ng h thng ch poweroff
reboot
Khi ng li h thng
shutdown
ng h thng
Bn phi l ngi s dng chnh c th c quyn ng h thng, nhng i khi ngi i din
cng c th thc hin iu ny.
Qun l File trong Unix

Tt c d liu trong Unix c t chc trong cc file. Tt c cc file c t chc trong cc th
mc. Nhng th mc ny c t chc trong mt cu trc cy m c gi l h thng file.
Khi bn lm vic vi Unix, bng cch ny hay cch khc, bn dnh hu ht thi gian lm vic vi
cc file. Chng ny s hng dn bn cch to v di chuyn cc file, sao chp v t li tn cho
chng, to lin kt cho chng.
Trong Unix, c 3 kiu file c bn:
1. Ordinary File: File thng, l mt file trn h thng m lu tr d liu, vn bn, hoc ch
dn chng trnh. Trong chng ny, bn s c hng dn cch lm vic vi nhng
file ny.
Page 7
2. Directory: Th mc, lu gi c cc file thng v c bit. Tng t vi cc th mc

trong Windown, Mac OS, th mc trong Unix l cc folder.
3. Special File: File c bit, mt s file c bit cung cp quyn truy cp vo phn cng nh
cc cng, CD-ROM, modem v cc u c Ethernet. Mt s file c bit khc l tng
t nh cc phm tt v khin bn c th truy cp vo mt file ring no bng cch s
dng cc tn khc nhau.
Lit k cc file trong Unix/Linux

lit k cc file v cc th mc lu gi trong th mc hin ti, bn s dng lnh sau:
$ls
Di y l v d v kt qu ca lnh trn.
$ls
bin
hosts
lib
res.03
ch07
hw1
pub
test_results
ch07.bak
hw2
res.01
users
docs
hw3
res.02
work
Lnh ls h tr ty chn -l gip bn nhn c nhiu thng tin hn v cc file c lit k.

$ls -l
total 1962188
drwxrwxr-x
2 amrood amrood
4096 Dec 25 09:59 uml
-rw-rw-r--
1 amrood amrood
5341 Dec 25 08:38 uml.jpg
drwxr-xr-x
2 amrood amrood
4096 Feb 15
2006 univ
drwxr-xr-x
2 root
root
4096 Dec
2007 urlspedia
-rw-r--r--
1 root
root
276480 Dec
2007 urlspedia.tar
drwxr-xr-x
8 root
root
drwxr-xr-x
-rwxr-xr-x
1 root
-rw-rw-r--
1 amrood amrood
200
300
root
4096 Nov 25
2007 usr
4096 Nov 25
2007 webthumb-1.01
3192 Nov 25
2007 webthumb.php
20480 Nov 25
2007 webthumb.tar
Page 8
-rw-rw-r--
1 amrood amrood
5654 Aug
2007 yourfile.mid
-rw-rw-r--
1 amrood amrood
166255 Aug
2007 yourfile.swf
drwxr-xr-x 11 amrood amrood
4096 May 29
2007 zlib-1.2.3
Di y l cc thng tin v tt c cc ct c lit k:

1. Ct u tin: biu din kiu file v s cho php c cung cp cho file. phn bn di l
miu t ca cc kiu file.
2. Ct 2: biu din lng b nh m file hoc th mc chim dng.
3. Ct 3: biu din s s hu ca file. l ngi s dng Unix to ra file ny.
4. Ct 4: biu din nhm s hu. Mi ngi s dng Unix c mt nhm lin kt.
5. Ct 5: biu din dung lng bng byte ca file.
6. Ct 6: biu din ngy thng m file c to hay chnh sa ln cui.
7. Ct 7: biu din tn file hoc th mc.
Trong v d v ls-l, mi dng file bt u vi mt k t d, -, hoc l. Nhng k t ny ch kiu ca file
c lit k.
Tin t
Miu t
File thng chng hn nh mt file vn bn ASCII, nh phn hoc ng link
cng.
Nhm file c bit. nhm file thit b u vo/u ra v d nh mt a cng
vt l.
File k t c bit. File thit b u vo/u ra th v d nh mt a cng vt
l.
File th mc m cha mt danh sch cc file v th mc khc.
Page 9
File lin kt k t. Kt ni trn bt k mt file thng no.
Pipe c t tn. Mt c cu giao tip lin tin trnh.
Socket c s dng cho giao tip lin tin trnh.
Cc siu k t trong Unix/Linux

Cc siu k t c ngha quan trng trong Unix. V d * v ? l siu k t. Chng ta s dng*
kt ni 0 hoc nhiu k t, s dng ? kt ni vi mt k t n.
V d:
$ls ch*.doc
Hin th tt c cc file m tn bt u vi cp k t ch v kt thc vi .doc.

ch01-1.doc
ch010.doc
ch02.doc
ch03-2.doc
ch04-1.doc
ch040.doc
ch05.doc
ch06-2.doc
ch01-2.doc ch02-1.doc c
Di y k t * thc hin kt ni vi bt k k t no. Nu bn mun hin th tt c cc file kt

thc vi .doc, th khi bn s dng lnh sau:
$ls *.doc
Cc file n trong Unix/Linux

Mt file khng nhn thy l mt file m cc k t u tin ca n l du chm (.). Cc chng trnh
Unix (bao gm shell) s dng hu ht nhng file ny gi cc thng tin cu hnh.
Mt vi v d v cc file n bao gm:
.profile: l script khi to Bourne shell (sh)
.kshrc: l script khi to Korn shell (ksh)
.cshrc: l script khi to C shell (csh)
.rhosts: l file nh hnh shell iu khin t xa.
Page 10
lit k cc file nhn khng nhn thy (b n), xc nh ty chn -a cho lnh ls:
$ ls -a
.profile
docs
lib
test_results
..
.rhosts
hosts
pub
users
.emacs
bin
hw1
res.01
work
.exrc
ch07
hw2
res.02
.kshrc
ch07.bak
hw3
res.03
Du chm n (.): i din cho th mc hin ti
Du chm kp (..): i din cho th mc gc.
To cc file trong Unix/Linux

Bn c th s dng vi editor to ra cc file thng trn h thng Unix. Bn ch cn n gin s
dng lnh sau:
$ vi filename
Lnh trn s m mt file vi tn cung cp. Bn s cn nhn phm i tin vo ch chnh

sa. Mt khi bn trong ch chnh sa, bn c th bt u vit ni dung vo file nh hnh di:
This is unix file....I created it for the first time.....
I'm going to save this content in this file.
Khi thc hin xong, bn lm theo cc bc sau:
Nhn phm esc thot khi ch ny
Nhn t hp phm Shift+ZZ thot khi file hon ton.
By gi bn s c mt file c to vi filename trong th mc hin ti.

$ vi filename
$
Chnh sa cc file trong Unix/Linux

Page 11
Bn c th chnh sa cc file hin ti bng cch s dng b son vi. Chng ta s i vo chi tit
tng phn trong mt chng hng dn c th. Nhng rt gn y, bn c th m mt file ang
tn ti nh sau:
$ vi filename
Mt khi file ny c m, bn c th tin vo ch chnh sa bng cch nhn phm i v sau

bn c th chnh sa ni dung nh bn thch. Nu bn mun di chuyn ti ni ny hoc ni khc
bn trong file, khi u tin bn cn thot khi ch chnh sa bng cch nhn phm esc, sau
bn c th s dng cc phm sau di chuyn bn trong mt file:
Phm l di chuyn sang pha bn phi;
Phm h di chuyn sang bn tri;
Phm k di chuyn ln pha trn trong mt file;
Phm j di chuyn xung pha di trong mt file
Do bng cch s dng cc phm trn, bn c th t con tr bt c v tr no bn mun chnh

sa. Mt khi bn xc nh v tr, sau bn c th s dng phm i tin vo ch chnh sa.
Sau khi bn thc hin xong, nhn esc v cui cng nhn t hp phmShift+ZZ thot khi file
hon ton.
Hin th ni dung ca mt file trong Unix/Linux

Bn c th s dng lnh cat quan st ni dung ca mt file. Di y l v d n gin quan
st ni dung ca mt file c to.
$ cat filename
$
Bn c th hin th s lng dng bng cch s dng ty chn -b cng vi lnh cat nh sau:
$ cat -b filename
1
Page 12
Tnh ton s lng t trong mt file trong Unix/Linux

Bn c th s dng lnh wc nhn c s dng, s lng t v s lng cc k t c trong
mt file. Di y l mt v d n gin quan st thng tin v file c to trn.
$ wc filename
2
19 103 filename
Di y l chi tit trong 4 ct:

1. Ct 1: i din cho tng s dng trong file ;
2. Ct 2: i din cho tng s t trong file ;
3. Ct 3: i din cho tng dung lng byte m file chim. y l kch thc thc ca file.
4. Ct 4: i din cho tn file.
Bn c th ng thi nhn c thng tin v nhiu file trong cng mt lc bng c php n gin
sau:
$ wc filename1 filename2 filename3
Sao chp cc file trong Unix/Linux

to mt bn sao ca mt file, bn s dng lnh cp. C php n gin ca lnh ny l:
$ cp source_file destination_file
Di y l v d to mt bn sao ca filename ang tn ti:

$ cp filename copyfile
$
By gi bn s tm thy mt copyfile trong th mc hin ti ca bn. File ny s ging hon

ton filename.
t li tn file
Page 13
thay i tn ca mt file, bn s dng lnh mv. C php n gin ca lnh ny l:

$ mv old_file new_file
Di y l mt v d m t li filename ang tn ti thnh newfile:

$ mv filename newfile
$
Lnh mv s di chuyn tt c file ang tn ti vo trong file mi. V th trong tnh hung ny bn s
ch tm thy mt newfile duy nht trong th mc hin ti.
Xa file
xa mt file ang tn ti, bn s dng lnh rm. C php n gin ca n l:
$ rm filename
Ch : C th rt nguy him khi xa mt file bi v n cha thng tin hu ch. V th bn cn phi

cn thn trong khi thc hin lnh ny. N ngh ty chn -i song song vi lnh rm.
Di y l v d m g b hon ton filename ang tn ti:
$ rm filename
$
Bn c th g b nhiu file ti cng mt lp nh sau:

$ rm filename1 filename2 filename3
$
Cc Unix Stream tiu chun trong Unix/Linux

Cc chi tit trong chng trnh Unix c 3 stream (hoc file) c m cho n khi n bt u:
1. stdin: N nh l mt u vo tiu chun (standard input) v phn t m t file lin kt l 0.
N cng c biu din nh l STDIN. Chng trnh Unix s c u vo mc nh t
STDIN.
Page 14
2. stdout: N nh l mt u ra tiu chun (standard output) v phn t m t file lin kt l 1.

N cng c biu din nh l STDOUT. Chng trnh Unix s vit u ra mc nh ti
STDOUT.
3. stderr: N nh l mt li tiu chun (standard error) v phn t m t file lin kt l 2. N
cng c biu din nh l STDERR. Chng trnh Unix s vit ton b thng tin li ti
STDERR.
Qun l th mc trong Unix

Mt th mc l mt file m nhim v duy nht ca n l lu gi tn v cc thng tin lin quan v
file. Tt c cc file, c th l file thng, c bit hoc th mc c gi trong cc th mc.
UNIX s dng mt cu trc th bc t chc cc file v th mc. Cu trc ny thng c
nhc n nh l mt cy th mc. Cy ny c mt im root node, mt k t gch cho (/) v tt
c cc th mc c cha di n.
Th mc gc (Home) trong Unix/Linux

Th mc m bn thy ngay khi bn ln u tin ng nhp vo l th mc chnh.
Bn s lm nhiu vic trong th mc chnh v cc th mc ph ni bn to ra t chc cc file
ca bn.
Bn c th tin vo th mc chnh bt c khi no bng cch s dng lnh sau:
$cd ~
$
Ti y biu tng ~ ch th mc chnh. Nu bn mun vo th mc chnh ca bt c ngi s

dng no khc, bn s dng lnh sau:
$cd ~username
$
vo th mc cui cng, bn c th s dng lnh sau:

$cd $
Page 15
Pathname tuyt i/quan h trong Unix/Linux

Cc th mc c sp xp trong mt h thng cp bc vi gc (/) trn cng. V tr ca bt k file
no trong h thng ny c miu t bi pathname ca n.
Cc phn t ca pathname l tch ring nhau bi mt du (/). Mt pathname l gi tr tuyt i nu
n c miu t trong mi lin quan vi gc, v th pathname tuyt i thng bt u vi mt
du (/).
Di y l v d v cc filename tuyt i.
/etc/passwd
/users/sjones/chem/notes
/dev/rdsk/Os3
Mt pathname c th trong mi quan h ti th mc lm vic hin ti ca bn. Cc pathname

tng i khng bao gi bt u vi (/). Lin quan n th mc chnh amrood, c mt s
pathname trng ging nh sau:
chem/notes
personal/res
xc nh ni bn ang trong h thng phn cp file vo bt k lc no, bn nhp lnhpwd

in th mc lm vic hin ti.
$pwd
/user0/home/amrood
Lit k cc th mc trong Unix/Linux

lit k danh sch cc th mc, bn c th s dng c php sau:
$ls dirname
Di y l v d lit k tt c file c cha trong th mc /usr/local.

$ls /usr/local
Page 16
X11
bin
gimp
jikes
sbin
ace
doc
include
lib
share
atalk
etc
info
man
ami
To cc th mc trong Unix/Linux
Cc th mc c to ra bng lnh sau:
$mkdir dirname
Ti y, th mc l pathname tuyt i hoc quan h m bn mun to ra. V d, lnh sau:

$mkdir mydir
$
To th mc mkdir trong th mc hin ti. Di y l v d:

$mkdir /tmp/test-dir
$
Lnh ny to th mc test-dir trong th mc /tmp. Lnh mkdir khng to u ra nu n thnh cng

to th mc yu cu.
Nu bn cung cp nhiu hn mt th mc trn dng lnh th mkdir to ra mi trong cc th mc.
V d:
$mkdir docs pub
$
N to ra th mc docs v pub di th mc hin ti.
To cc th mc cha (parent) trong Unix/Linux

i khi bn mun to mt th mc, th mc chnh hoc cc th mc ca n khng tn ti. Trong
trng hp ny, lnh mkdir a ra mt thng bo li nh sau:
$mkdir /tmp/amrood/test
mkdir: Failed to make directory "/tmp/amrood/test";
No such file or directory
$
Page 17
Trong trng hp trn, bn c th ch nh ty chn -p ti lnh mkdir. N to tt c cc th mc

cn thit cho bn. V d:
$mkdir -p /tmp/amrood/test
$
Lnh trn to tt c cc th mc chnh cn thit.
D b cc th mc trong Unix/Linux
Cc th mc c th c xa bng cch s dng lnh rmdir nh sau:
$rmdir dirname
$
Ghi ch: d b mt th mc, bn nn chc chn n khng cn cha d liu quan trng no,
ngha l khng c bt k file hoc th mc ph bn trong th mc ny.
Bn c th d b nhiu th mc ti cng thi im nh sau:
$rmdir dirname1 dirname2 dirname3
$
Lnh trn d b cc th mc dirname1, dirname2 v dirname3 nu chng l trng. Lnh rmdir

khng to ra u ra nu n thc hin thnh cng.
Thay i cc th mc trong Unix/Linux

Bn c th s dng lnh cd to nhiu thay i ti th mc home. Bn c th s dng n
thay i bt k th mc no bng cch xc nh path tuyt i v quan h hp l. C php nh
sau:
$cd dirname
$
Ti y, dirname l tn ca th mc m bn mun to cc thay i. V d, lnh:

$cd /usr/local/bin
$
Page 18
To thay i ti th mc /usr/local/bin. T th mc ny bn c th cd th mc /usr/home/amrood

bng cch s dng path quan h sau:
$cd ../../home/amrood
$
t li tn cc th mc trong Unix/Linux
Lnh mv c th c s dng t li tn mt th mc. C php nh sau:
$mv olddir newdir
$
Bn c th t li tn mt th mc mydir thnh yourdir nh sau:

$mv mydir yourdir
$
Cc th mc .(dot) v .. (dot dot) trong Unix/Linux

Tn file l .(dot) biu din th mc lm vic hin ti; v tn file l .. (dot dot) biu din th mc
lp trn th mc lm vic hin ti, thng l th mc chnh.
Nu chng ta nhp lnh ny ch mt danh snh cc th mc lm vic hin ti v s dng ty
chn -a lit k tt c cc file v ty chn -l cung cp kiu danh sch di, iu ny s cho ra kt
qu sau:
$ls -la
drwxrwxr-x
teacher
drwxr-xr-x
60
root
----------
teacher
-rwxr-xr-x
teacher
class
2048
Jul 16 17.56 .
1536
Jul 13 14:18 ..
class
4210
May 1 08:27 .profile
class
1948
May 12 13:42 memo
Quyn hn/Ch truy cp file trong Unix

Quyn s hu file l mt thnh phn quan trng ca Unix m cung cp phng thc bo mt
lu gi file. Mi file trong Unix c cc thuc tnh sau th hin quyn hn truy cp ti n (File
Permission):
Page 19
Quyn hn truy cp ca ngi s hu: Quyn hn truy cp ca ch nhn quyt nh

nhng hnh ng g m ngi s hu c th thc hin trn file.
Quyn hn truy cp nhm: Quyn hn truy cp ca nhm quyt nh hnh ng g m

ngi s dng, thnh vin ca nhm m s hu file, c th thc hin trn file.
Cc quyn hn truy cp khc: Ch hnh ng no m tt c nhng ngi s dng c th

thc hin trn file.
Cc du hiu v quyn hn truy cp

Trong khi s dng lnh ls -l, n hin th cc thng tin a dng lin quan n quyn hn truy cp
trn file nh sau:
$ls -l /home/amrood
-rwxr-xr--
1 amrood
users 1024
Nov 2 00:10
myfile
drwxr-xr--- 1 amrood
users 1024
Nov 2 00:10
mydir
Ti y, ct u tin i din cho cc ch truy cp khc nhau, v d nh quyn hn truy cp lin

kt vi mt file hoc th mc.
Cc quyn hn truy cp c chia thnh ba nhm, m mi v tr trong nhm biu hin mt quyn
hn truy cp c th, theo th t: c (r), vit (w) v thc thi (x):
Cc k t u tin t 1 n 3 (2-4 trong dy k c du -) i din quyn hn truy cp cho

ngi s hu file. V d -rwxr-xr-- biu din rng ngi s hu c cho php c (r), vit
(w), v chy chng trnh (x).
Nhm 3 k t tip theo t 5-7 i din cho quyn hn truy cp nhm ti nhng file s hu.
V d -rwxr-xr-- i din rng nhm c cho php c (r) v thc thi (x), nhng khng cho
php vit (w)
Nhm 3 k t cui cng t 8-10 i din quyn hn truy cp khc. V d -rwxr-xr--i din
rng ai trn th gii ch cho php c (r).
Ch truy cp vo file trong Unix/Linux

Quyn hn truy cp ca mt file l dng u tin ca s bo v trong h thng Unix. Cc khi xy
dng c bn trong quyn hn truy cp Unix l cc quyn hn truy cp c, vit v thc thi c
miu t di y:
Page 20
1. c:
Cho php c ni dung ca file.
2. Vit:
Cho php chnh sa hoc g b ni dung ca file.
3. Thc thi:
Ngi s dng vi quyn hn truy cp thc thi c th chy mt file nh l mt chng trnh.
Ch truy cp vo th mc
Cc ch truy cp vo th mc c lit k v t chc trong cng mt cch nh trong bt k mt
file no. C mt vi im khc nhau m bn cn ch :
1. c:
Truy cp vo mt th mc vi ngha l ngi s dng c th c cc ni dung. Ngi s dng c
th xem tn cc file bn trong mt th mc.
2. Vit
Cho php ngi s dng c th thm hoc xa file ni dung ca th mc.
3. Thc thi:
Chy mt th mc khng thc s mang nhiu ngha, v th bn ch coi l giy php ngang
qua.
Mt ngi s dng phi c quyn truy cp thc thi ti th mc bin chy lnh ls hoc cd chng
hn.
Thay i cc quyn hn truy cp trong Unix/Linux

thay i quyn hn truy cp ca file hoc th mc, bn s dng lnh chmod (vit tt ca
change mode). C hai cch s dng chmod l: ch tng trng (Symbolic Mode) v ch
tuyt i (Absolute Mode).
S dng chmode trong ch tng trng

Page 21
Cch d nht cho ngi mi bt u chnh sa quyn hn truy cp file hoc th mc l s

dng ch tng trng. Vi ch ny bn c th thm, xa hoc xc nh tp hp cc cho
php m bn mun bng cch s dng cc ton t sau:
Ton t chmod
Miu t
Thm quyn hn truy cp c ch nh ti mt file hoc tp

G b quyn hn truy cp c ch nh t mt file hoc
th mc
Thit lp cc quyn hn truy cp c ch nh.
Di y l mt v d bng cch s dng lnh testfile. Chy ls -1 trn testfile ch rng quyn hn
truy cp ca file l nh sau:
$ls -l testfile
-rwxrwxr--
1 amrood
users 1024
Nov 2 00:10
testfile
Sau mi v d lnh chmod t bng trc c chy trn testfile, theo sau bi ls -l v th bn c
th quan st cc thay i ca quyn hn truy cp.
$chmod o+wx testfile
$ls -l testfile
-rwxrwxrwx
1 amrood
users 1024
Nov 2 00:10
testfile
users 1024
Nov 2 00:10
testfile
users 1024
Nov 2 00:10
testfile
$chmod u-x testfile

$ls -l testfile
-rw-rwxrwx
1 amrood
$chmod g=rx testfile

$ls -l testfile
-rw-r-xrwx
1 amrood
Ti y l cch bn c th kt ni nhng lnh ny trn mt dng n:

$chmod o+wx,u-x,g=rx testfile
$ls -l testfile
Page 22
-rw-r-xrwx
1 amrood
users 1024
Nov 2 00:10
testfile
S dng chmod vi quyn hn truy cp tuyt i trong

Unix/Linux
Cch th hai chnh sa quyn hn truy cp vi lnh chmod l s dng s xc nh cc
quyn hn truy cp cho file.
Mi quyn hn truy cp c n nh bng mt gi tr, nh trong bng di, v tng ca mi
quyn hn truy cp cung cp mt s cho tp hp thit lp .
i din cho quyn hn truy cp trong h c s 8
Tham chiu
Khng cho php
---
Cho php thc thi
--x
Cho php vit
-w-
Cho php thc thi v vit: 1 (thc thi) + 2 (vit) = 3
-wx
Cho php c
r--
Cho php c v thc thi: 4(c) + 1 (thc thi) = 5
r-x
Cho php c v vit: 4 (c) + 2 (vit) = 6
rw-
Cho php tt c: 4 (c) + 2 (vit) + 1 (thc thi) = 7
rwx
Ti y l mt v d s dng testfile. Chy ls -1 trn testfile ch rng cc quyn hn truy cp ca file

l nh sau:
$ls -l testfile
-rwxrwxr--
1 amrood
users 1024
Nov 2 00:10
testfile
Mi v d lnh chmod t bng trc c chy trn testfile, theo sau bi ls -l v th bn c th

quan st cc thay i ca quyn hn truy cp:
Page 23
$ chmod 755 testfile

$ls -l testfile
-rwxr-xr-x
1 amrood
users 1024
Nov 2 00:10
testfile
users 1024
Nov 2 00:10
testfile
users 1024
Nov 2 00:10
testfile
$chmod 743 testfile

$ls -l testfile
-rwxr---wx
1 amrood
$chmod 043 testfile

$ls -l testfile
----r---wx
1 amrood
Thay i ngi s hu v nhm trong Unix/Linux

Trong khi to mt ti khon trn Unix, n gn mt ID ngi s hu v mt ID s hu nhm cho
mi ngi s dng. Tt c cc quyn hn truy cp cp trn l cng c gn da trn ngi
s hu v nhm.
Hai lnh c sn thay i s hu c nhn v s hu nhm ca file l:
1. chown: Lnh ny i din cho thay i s hu c nhn (change owner).
2. chgrp: Lnh ny i din cho thay i s hu nhm (change group).
Thay i quyn s hu trong Unix/Linux

Lnh chown thay i quyn s hu ca mt file. C php c bn l:
$ chown user filelist
Gi tr ca user c th l tn hoc ID ca ngi s dng trn h thng. V d:

V d:
$ chown amrood testfile
$
Thay i ngi s hu ca file cho ti ngi s hu amrood.

Ghi ch: Ngi s hu gc c quyn khng b hn ch thay i quyn s hu ca bt k file
no nhng ngi s hu thng thng ch c th thay i quyn s hu ca nhng file m h s
hu.
Page 24
Thay i quyn s hu nhm trong Unix/Linux

Lnh chrgp thay i s hu nhm ca file. C php n gin l:
$ chgrp group filelist
Gi tr ca group c th l tn hoc ID ca nhm trn h thng. V d:

V d:
$ chgrp special testfile
$
Thay i s hu nhm chn ti nhm special.
Quyn hn truy cp SUID v SGID (thit lp ID c

nhn v nhm) trong Unix/Linux
Thng thng khi mt lnh c chy, n s phi chy cng vi cc c quyn c bit thc
hin nhim v ca n.
Nh mt v d, khi bn thay i mt khu vi lnh passwd, mt khu mi c gi trong tp
/etc/shadow.
Khi l mt ngi s dng thng, bn khng c c quyn truy cp c hoc vit ti file ny
do cc l do bo mt, nhng khi bn thay i mt khu, bn cn c quyn vit ti file ny. iu ny
c ngha l chng trnh passwd phi cung cp cho bn cc quyn thm bn c th vit
etc/shadow.
Cc quyn thm vo c cung cp ti chng trnh thng qua mt k thut c bit n
l Thit lp ID ngi s dng (Set User ID SUID bit) v Thit lp ID nhm (Set Group ID SGID
bit).
Khi bn chy mt chng trnh m c quyn hn truy cp SUID, bn s dng n thay i s
hu ca chng trnh . Cc chng trnh m khng thit lp SUID th ang chy vi quyn hn
truy cp ca ngi s dng m khi ng chng trnh.
iu ny l ng vi SGID. Cc chng trnh thng thng chy vi quyn hn truy cp nhm,
nhng thay vo , n ch thay i s hu nhm cho chng trnh ang chy ch khng thay i
cho chng trnh khc ca nhm.
Page 25
Cc bit SUID bit v SGID bit s xut hin bng k t s nu quyn hn truy cp l c sn. SUID s
bit s c t trong cc permission bit, ni m ngi s hu thc thi s c thm quyn. V d,
lnh sau:
$ ls -l /usr/bin/passwd
-r-sr-xr-x
root
bin
19031 Feb 7 13:47
/usr/bin/passwd*
iu ny ch rng SUID bit c thit lp v lnh c s hu bi s hu gc. K t vit hoa S

trong v tr thc thi thay cho ch thng s ch rng bit ca thc thi khng c thit lp.
Nu sticky bit c cho php trn th mc, cc file ch c th c g b nu bn l mt trong
nhng ngi s dng sau:
Ngi s hu ca th mc sticky;
Ngi s hu ca cc file b g b;
Ngi s hu gc
thit lp cc SUID bit v SGID bit cho bt k th mc, bn th c php sau:

$ chmod ug+s dirname
$ ls -l
drwsr-sr-x 2 root root
4096 Jun 19 06:45 dirname
Ci t mi trng Unix/Linux
Mt khi nim Unix quan trng l environment, m c nh ngha bi cc bin mi trng. Mt
s c thit lp bi h thng, s khc c thit lp bi bn, bi shell hoc bt k chng trnh
m bn ti v.
Mt bin l mt chui k t m chng ta gn mt gi tr. Gi tr c ch nh c th l mt s, vn
bn, tn file, thit b hoc bt k kiu d liu khc.
V d, u tin chng ta thit lp mt bin TEST v sau chng ta truy cp gi tr ca n bng
cch s dng lnh echo.
Page 26
$TEST="Unix Programming"
$echo $TEST
Unix Programming
Ghi ch rng cc bin mi trng c thit lp m khng s dng k hiu $ nhng trong khi truy
cp chng, chng ta s dng k hiu $ nh l mt tin t. Nhng bin ny gi gi tr ca chng
cho n khi chng ta thot khi shell.
Khi bn ng nhp vo h thng, Shell di ch khi to thit lp mi trng bin. iu
ny thng l tin trnh 2 bc m bao gm Shell c cc file sau:
/etc/profile
profile
Tin trnh nh sau:

1. Kim tra shell thy /etc/profile c tn ti hay khng..
2. Nu n tn ti, Shell c n. Nu khng th, file ny b b qua. Khng c thng bo li hin
th.
3. Shell kim tra file .profile c tn ti hay khng trong th mc chnh ca bn. Th mc chnh
l th mc m bt u khi bn ng nhp thnh cng vo h thng.
4. Nu n tn ti, Shell c n; nu khng th, Shell b qua. S khng c thng bo li c
hin th.
Ngay sau khi c hai file trn c c, Shell hin th mt dng nhc:
$
y l dng nhc m ti bn c th nhp lnh thc thi chng.

Ghi ch - Tin trnh khi to Shel c lit k chi tit y p dng cho tt c Shell kiuBourne,
nhng mt vi file c thm vo c s dng bi bash v ksh.
.profile File trong Unix/Linux:

File /etc/profile c duy tr bi ngi qun l h thng v cha ng thng tin khi to Shell
c yu cu bi tt c ngi s dng trn h thng.
Page 27
File .profile l di quyn kim sot ca bn. Bn c th nhp thm thng tin Shell ty theo bn
mun ti file ny. Thng tin t nht m bn cn thit lp bao gm:
Kiu terminal m bn ang s dng
Danh sch cc th mc m trong t v tr cc lnh
Danh sch cc bin ca kiu terminal ca bn.
Bn c th kim tra .profile trong th mc chnh. M n bng cch s dng b son vi v kim tra
tt c cc bin thit lp cho mi trng ca bn.
Thit lp kiu terminal trong Unix/Linux

Thng th kiu terminal bn ang s dng l c nh hnh t ng bng chng
trnhlogin hoc getty. i khi, tin trnh nh hnh t ng ny d on kiu terminal ca bn
khng chnh xc.
Nu kiu terminal khng c thit lp chnh xc, kt qu ca lnh c th trng kh l, hoc bn
khng th tng tc vi Shell mt cch chnh xc.
m bo khng xy ra trng hp ny, hu ht ngi s dng thit lp kiu terminal ca h ti
dng mu s chung thp nht nh sau:
$TERM=vt100
$
Thit lp PATH trong Unix/Linux:

Khi bn g bt k lnh no trn dng nhc lnh, Shell phi xc nh v tr lnh trc khi n c th
c thc thi.
Bin PATH xc nh v tr trong Shell s tm kim cc lnh. Thng th n c thit lp nh
sau:
$PATH=/bin:/usr/bin
$
Ti y mi cng vo (entry) c thit lp ring r bi du hai chm : l cc th mc. Nu bn

yu cu Shell thc thi mt lnh v n khng th tm kim lnh trong bt k th mc c
cung cp bin PATH, mt thng tin tng t nh sau xut hin:
Page 28
$hello
hello: not found
$
Cc bin PS1 v PS2 c bn lun trong mc k tip.
Cc bin PS1 v PS2 trong Unix/Linux

Cc k t m Shell hin th khi dng nhc lnh c gi trong bin PS1. Bn c th thay i bin
ny ti bt k ci g bn mun. Ngay sau khi bn thay i n, n s c s dng bi shell t thi
im .
V d, nu bn thng bo lnh:
$PS1='=>'
=>
=>
=>
Dng nhc c th tr thnh =>. thit lp gi tr ca PS1 n ch th mc lm vic, thng bo

lnh sau:
=>PS1="[\u@\h \w]\$"
[root@ip-72-167-112-17 /var/www/tutorialspoint/unix]$
[root@ip-72-167-112-17 /var/www/tutorialspoint/unix]$
Kt qu ca lnh ny l dng nhc lnh hin th tn s dng ca ngi dng, tn hostname, v th

mc lm vic.
C mt vi dy thot (escape) c s dng lm tham s gi tr cho PS1, v th c gng gii hn
chnh bn dng nhc khng ln t thng tin.
Dy escape
Miu t
\t
Thi gian hin ti, din t dng HH:MM:SS
\d
Ngy hin ti, din t dng Ngy trong tun Thng Ngy
Page 29
\n
Dng mi
\s
Mi trng Shell hin ti
\W
Th mc lm vic
\w
ng Path y ca th mc lm vic
\u
Tn s hu hin ti ca ngi s dng
\h
Hostname ca thit b hin ti
\#
\$
S lng lnh ca lnh hin ti. Tng mi khi c mt lnh mi c

nhp
Nu UID hiu qu l 0 ( l, nu bn c ng nhp nh l root),
kt thc dng nhc vi k t #; nu khng th, s dng $.
Bn c th to s thay i bi chnh bn mi khi bn ng nhp vo, hoc bn c th c thay i

c to mt cch t ng trong PS1 bng cch thm n ti file .profile.
Khi bn thng bo mt lnh m cha hon thin, Shell s hin th mt dng nhc lnh th hai v
i bn hon thin lnh v nhp li.
Dng nhc lnh mc nh th hai l k hiu ln hn >, nhng c th c thay i bng cch nh
ngha li bin PS2.
Di y l v d v cch s dng dng nhc lnh th hai:
$ echo "this is a
> test"
this is a
test
$
Tip theo l v d m nh ngha li PS2 vi mt dng nhc c ty chnh theo ban:
Page 30
$ PS2="secondary prompt->"
$ echo "this is a
secondary prompt->test"
this is a
test
$
Cc bin mi trng trong Unix/Linux

Di y l mt danh sch cc b ca cc bin mi trng quan trng. Nhng bin ny s c
thit lp v truy cp nh cp phn trn.
Bin
DISPLAY
HOME
IFS
Miu t
Cha ng b nhn din cho s hin th m cc chng trnh X11 nn
s dng bi mc nh.
Ch dn th mc chnh ca ngi s dng hin ti: tham s mc nh
cho lnh cd c sn.
Ch dn Internal Field Separator m c s dng bi s phn tch t
ang tch sau s m rng.
LANG m rng Locale h thng mc nh; LC_ALL c th c s
LANG
dng vit ln (c quyn u tin cao hn) iu ny. V d, nu gi

tr ca n l pt_BR, th sau ngn ng c thit lp l (Brazilian)
Portuguese v min a phng l Brazil.
Trn nhiu h thng Unix vi mt Dynamic Linker, cha mt danh sch
LD_LIBRARY_PATH
du hai chm ring r ca cc th mc m Dynamic Linker tm kim

cc i tng c chia s khi xy dng mt hnh nh tin trnh sau
khi thc thi, trc khi tm kim bt k th mc khc.
PATH
Ch dn tm kim path cho cc lnh. N l mt danh sch du hai chm

ring r ca cc th mc m trong Shell tm kim cho cc lnh.
Page 31
PWD
RANDOM
SHLVL
TERM
TZ
UID
Ch dn th mc lm vic hin ti khi thit lp bi lnh cd.

To mt s nguyn ngu nhin gia 0 v 32767 mi khi n c nhc
n.
Lng gia bi mi khi bash c bt u. Bin ny hu dng khi xc
nh c hay khng lnh exit c sn kt thc mc hin ti.
Lin quan kiu hin th.
Lin quan min thi gian (time zone). N c th nhn cc gi tr nh
GMT, AST.
M rng ID s dng dng s ca ngi s dng hin ti, khi to khi
Shell bt u.
Di y l v d minh ha mt vi bin mi trng:

$ echo $HOME
/root
]$ echo $DISPLAY
$ echo $TERM
xterm
$ echo $PATH
/usr/local/bin:/bin:/usr/bin:/home/amrood/bin:/usr/local/bin
$
Cc tin ch c bn: in, email trong Unix

n chng ny, bn c mt vi nhn thc c bn v h thng Unix v mt s lnh c bn ca
n. Chng ny s s qua v mt s tin ch c bn nhng quan trng trong cc tin ch ca Unix
m bn s s dng chng trong hot ng thng nht.
In cc file trong Unix/Linux

Page 32
Trc khi bn in mt file trn h thng Unix, bn c th mun nh dng li n ty chnh cc l,

nh du mt vi t,. Hu ht cc file c th c in m khng cn nh dng li, nhng bn in
th nh vy thng trng khng c p cho lm.
Rt nhiu phin bn ca Unix bao gm hai trnh nh dng vn bn rt tin ch: nroff vtroff.
Chng khng c tm hiu trong chng ny nhng bn c th tm hiu tin ch ca chng thng
qua mng.
Lnh pr trong Unix/Linux

Lnh pr phn nh qu trnh nh dng file trn mn hnh terminal hoc cho mt my in. V d, nu
bn c mt danh sch tn di ca mt file, bn c th nh dng n trn mn hnh vo hai hay
nhiu ct.
Di y l c php lnh pr:
pr option(s) filename(s)
Lnh pr thay i nh dng ca file ch trn mn hnh hoc trn bn in, n khng chnh sa file ban
u. Bng di y lit k mt vi ty chn ca lnh pr:
Chc nng
Miu t
-k
To ra k ct u ra.
-d
Khong trng kp u ra (khng phi trn tt c phin bn pr).
-h "header"
Lm cho mc mi tr thnh nh mt u ca bn bo co.
-t
Kh l khi in u v cc l trn/di.
-l PAGE_LENGTH
Thit lp di trang ti PAGE_LENGTH (66) dng. S t mc nh

ca cc dng l 56.
-o MARGIN
In pxet mi dng vi khong cch l l 0.
-w PAGE_WIDTH
Thit lp rng ti PAGE_WIDTH (72) k t ch cho u ra dng
Page 33
nhiu ct.
Trc khi s dng pr, di y l cc ni dung ca mt file mu: food.
$cat food
Sweet Tooth
Bangkok Wok
Mandalay
Afghani Cuisine
Isle of Java
Big Apple Deli
Sushi and Sashimi
Tio Pepe's Peppers
........
$
By gi chng ta s dng lnh pr to mt bn bo co c 2 ct vi u l Restaurents:

$pr -2 -h "Restaurants" food
Nov
9:58 1997
Restaurants
Page 1
Sweet Tooth
Isle of Java
Bangkok Wok
Big Apple Deli
Mandalay
Sushi and Sashimi
Afghani Cuisine
Tio Pepe's Peppers
........
$
Cc lnh Ip v Ipr trong Unix/Linux

Lnh Ip hoc Ipr in mt file trn giy t mn hnh hin th. Mt khi bn nh dng file s dng
lnh pr v sn sng in, bn c th s dng bt c lnh no trong 2 lnh ny in file ca bn
trn my in kt ni c vi my tnh ca bn.
Qun l h thng c th thit lp my in mc nh ti site ca bn. in mt file c tn l food
trn my in mc nh, bn s dng lnh lp hoc lpr nh trong v d sau:
Page 34
$lp food
request id is laserp-525
(1 file)
Lnh Ip ch mt ID m bn c th s dng dng cng vic in hoc kim tra trng thi ca n.
Nu bn s dng lnh Ip, bn c th s dng chc nng -nNum in s lng bn sao l

Num. Cng vi lnh Ipr, bn c th s dng ty chn -Num thc hin vic tng t.
Nu c nhiu my in kt ni vi my tnh ca bn, th khi bn c th chn mt my in

bng cch s dng ty chn dprinter vi lnh Ip v s dng ty chn -Pprinter vi lnh
Ipr cho mc ch tng t. Ti y, printer l tn my in.
Cc lnh Ipstat v Ipq trong Unix/Linux

Lnh Ipstat ch nhng g trong hng my in: ID yu cu, c file, khi cc cng vic c gi cho
mc ch in, v cc trng thi ca cc yu cu.
S dng Ipstat -o nu bn mun quan st ton b cc yu cu u ra ch khng phi ch cc yu
cu ca ring bn. Cc yu cu c trnh by theo th t chng c in:
$lpstat -o
laserp-573
john
128865
Nov 7
11:27
laserp-574
grace
82744
Nov 7
11:28
laserp-575
john
23347
Nov 7
11:35
on laserp
Lnh Ipq cung cp thng tin hi khc vi lnh Ipstat -o:

$lpq
laserp is ready and printing
Rank
Owner
Job
Files
Total Size
active john
573
report.ps
128865 bytes
1st
grace
574
ch03.ps ch04.ps
82744 bytes
2nd
john
575
standard input
23347 bytes
Page 35
y dng u tin hin th trng thi my in. Nu my in khng hot ng hoc ang ht giy,
bn c th quan st cc thng tin khc trn dng u tin.
Cc lnh cancel v Iprm trong Unix/Linux

Lnh cancel kt thc yu cu in t lnh Ip. Lnh Iprm kt thc cc yu cu ca Ipr. Bn c th xc
nh hoc ID ca yu cu (hin th bi lnh Ip hoc Ipq) hoc tn ca my in.
$cancel laserp-575
request "laserp-575" cancelled
$
dng cc yu cu hin ti ang in, bt chp ID ca n, n gin bn nhn cancel v tn my

in:
$cancel laserp
request "laserp-573" cancelled
$
Lnh Iprm s dng cng vic ang thc hin nu lnh do bn ra. Nu khng th, bn c th
cung cp cc tn cng vic nh l tham s hoc s dng mt du gch ngang (-) g b tt c
cng vic ca bn:
$lprm 575
dfA575diamond dequeued
cfA575diamond dequeued
$
Lnh Iprm ni cho bn v cc tn file thc s b d b t hng in.
Gi Email trong Unix/Linux

Bn s dng lnh mail gi v nhn mail. Di y l c php gi mt Email:
$mail [-s subject] [-c cc-addr] [-b bcc-addr] to-addr
Bng di lit k cc chc nng quan trng lin quan n lnh mail:
Chc nng
Miu t
Page 36
-s
-c
-b
Xc nh subject trn dng lnh.

Gi cc bn sao carbon ti danh sch ca cc ngi s dng. Danh
sch c th l mt bn danh sch tn phn bit bng du phy.
Gi cc bn sao blind carbon ti danh sch. Danh sch c th l mt
bn danh sch tn phn bit bng du phy.
Di y l v d gi mt Test message ti a ch admin@yahoo.com.

$mail -s "Test Message" admin@yahoo.com
Bn sau c mong i g vn bn vo thng bo ca bn, theo sau bi mt control-D ti

phn bt u ca mt dng. dng vic g vn bn ny, n gin bn g du chm (.) nh sau:
Hi,
This is a test
.
Cc:
Bn c th gi mt file y bng cch s dng mt ton t iu hng li < nh sau::

$mail -s "Report 05/06/07" admin@yahoo.com < demo.txt
kim tra cc th n trong h thng Unix ca mnh, bn g lnh email nh sau:

$mail
no email
Filter v Pipe trong Unix

Bn c th kt ni hai lnh vi nhau m u ra ca mt chng trnh l u vo ca chng
trnh tip theo. Hai hoc nhiu lnh c kt ni trong cch ny to thnh mtpipe.
to mt pipe, t mt thanh dc (|) trn dng lnh gia hai lnh.
Khi mt chng trnh nhn u vo t mt chng trnh khc, thc hin mt vi hot ng trn
u vo , v vit kt qu cho u ra, n c cp nh l mt filter.
Page 37
Lnh grep trong Unix/Linux

Chng trnh grep tm mt file hoc cc file cho cc dng m c mt mu no . C php ca n
l:
$grep pattern file(s)
Tn grep bt ngun t lnh ed (UNIX line editor), g/re/p c ngha l globally search for a regular
expression and print all lines containing it (tm kim ton cu cho mt regular expression v in tt
c dng cha n)."
Mt regular expression l hoc mt vi on thun vn bn hoc cc k t c bit s dng cho
cc kt ni mu.
Cch s dng n gin nht ca grep l tm kim mt mu cha mt t n. N c th th c
s dng trong mt pipe m ch trong nhng dng ny ca cc file u vo cha mt chui
cho c gi ti u ra tiu chun. Nu bn khng cung cp cho grep mt tn file c, n c
u vo tiu chun, y l cch m tt c cc filter lm vic.
$ls -l | grep "Aug"
-rw-rw-rw-
1 john
doc
11008 Aug
6 14:10 ch02
-rw-rw-rw-
1 john
doc
8515 Aug
6 15:30 ch07
-rw-rw-r--
1 john
doc
2488 Aug 15 10:51 intro
-rw-rw-r--
1 carol doc
1605 Aug 23 07:35 macros
C cc chc nng khc nhau m bn c th s dng song song vi lnh grep:
Chc nng
Miu t
-v
In tt c cc dng m khng kt ni vi mu cho.
-n
In cc dng kt ni v s dng ca n.
-l
Ch in tn file vi cc dng kt ni.
-c
Ch in s lng cc dng kt ni.
Page 38
Kt ni hoc vi ch hoa hoc ch thng.
-i
By gi, chng ta s dng mt regular expression m ni cho lnh grep tm cc dng vi

carol, theo sau bi khng hoc nhiu k t khc c tm tt trong mt regular expression nh
l du sao *, sau theo sau bi Aug.
y chng ta ang s dng chc nng -i c s tm kim phn bit ch hoa vi ch thng:
$ls -l | grep -i "carol.*aug"
-rw-rw-r--
1 carol doc
1605 Aug 23 07:35 macros
Lnh sort trong Unix/Linux

Lnh sort sp xp cc dng ca vn bn theo th t ch ci hoc th t s. V d bn di xp
hng cc dng trong mt food file.
$sort food
Afghani Cuisine
Bangkok Wok
Big Apple Deli
Isle of Java
Mandalay
Sushi and Sashimi
Sweet Tooth
Tio Pepe's Peppers
$
Lnh sort, theo mc nh, sp xp cc dng ca vn bn theo th t ch ci. C rt nhiu chc

nng m iu khin vic sp hng ny:
Chc nng
Miu t
-n
Sp xp theo th t s, b qua cc khong trng v cc tab.
-r
Nghch o th t ca s sp xp.
Page 39
-f
Sp xp ch hoa v ch thng cng vi nhau.
+x
B qua cc x trng u tin khi sp xp.
C th c nhiu hn hai lnh c kt ni trong mt pipe. V d v pipe trn s dng grep, chng
ta c th sp xp cc file theo cch khc l bng cch chnh sa theo th t kch c trong August.
Pipe sau cha cc lnh: ls, grep, v sort:
$ls -l | grep "Aug" | sort +4n
-rw-rw-r--
1 carol doc
1605 Aug 23 07:35 macros
-rw-rw-r--
1 john
doc
2488 Aug 15 10:51 intro
-rw-rw-rw-
1 john
doc
8515 Aug
6 15:30 ch07
-rw-rw-rw-
1 john
doc
11008 Aug
6 14:10 ch02
Pipe ny sp xp tt c cc file trong th mc ca bn c chnh sa theo th t kch c trong

August v in chng ti mn hnh terminal. Chc nng +4n b qua 4 trng (cc trng m phn
bit bi khong trng), sau sp xp cc dng theo th t s.
Cc lnh pg v more trong Unix/Linux

Mt u ra di thng lm trn mn hnh, nhng nu bn chy vn bn thng
qua morehoc pg nh l mt filter th mn hnh hin th s dng sau mi khi mn hnh y vn
bn.
Chng ta gi s rng bn c mt danh sch th mc di. lm cho n d dng hn khi c danh
sch c sp xp ny, dn output thng qua lnh more nh sau:
$ls -l | grep "Aug" | sort +4n | more
-rw-rw-r--
1 carol doc
1605 Aug 23 07:35 macros
-rw-rw-r--
1 john
doc
2488 Aug 15 10:51 intro
-rw-rw-rw-
1 john
doc
8515 Aug
6 15:30 ch07
-rw-rw-r--
1 john
doc
14827 Aug
9 12:40 ch03
.
.
.
Page 40
-rw-rw-rw-
1 john
doc
16867 Aug
6 15:56 ch05
--More--(74%)
Mn hnh s c ph y bi cc vn bn cha trong cc dng c sp xp theo th t kch

c. Ti v tr cui cng ca mn hnh, ti dng nhc lnh more bn c th g mt lnh di chuyn
qua phn vn bn c sp xp.
Khi bn lm vic vi mn hnh ny, bn c th s dng bt k lnh trong s cc lnh c lit k
trong chng trnh.
Qun l tin trnh trong Unix

Khi bn chy mt chng trnh trn h thng Unix, h thng to mt mi trng c bit cho
chng trnh . Mi trng ny cha mi th cn thit cho h thng chy chng trnh nu nh
khng c chng trnh khc ang chy trn h thng.
Bt c khi no bn thng bo mt lnh trong Unix, n to hoc bt u mt tin trnh mi. Khi bn
c gng thc hin mt lnh ls lit k ni dung th mc, bn bt u mt tin trnh. Mt tin
trnh, hiu theo cch n gin, l mt v d ca mt chng trnh ang chy.
H iu hnh theo di cc tin trnh thng qua mt ID c 5 k s m c bit nh l ID pidhoc
Process ID. Mi tin trnh trong h thng c mt pid duy nht.
Pid thng lp li bi v tt c cc s c th c s dng v pid k tip lp li. Ti bt k lc
no, khng th c hai tin trnh vi hai pid ging nhau cng tn ti trong h thng bi v n l pid
m Unix s dng theo di mi tin trnh.
Bt u mt tin trnh trong Unix/Linux

Khi bn bt u mt tin trnh (chy mt lnh), c 2 cch bn chy n:
Foreground Process
Background Process
Tin trnh Foreground trong Unix/Linux

Theo mc nh, mi tin trnh m bn bt u chy l Foreground Process. N nhn input t bn
phm v gi output ti mn hnh.
Page 41
Bn c th quan st iu ny xy ra vi lnh ls. Nu bn mun lit k tt c cc file trong th mc

hin ti, bn c th s dng lnh sau:
$ls ch*.doc
N s hin th tt c file m tn bt u vi ch v kt thc vi .doc.

ch01-1.doc
ch010.doc
ch02.doc
ch03-2.doc
ch04-1.doc
ch040.doc
ch05.doc
ch06-2.doc
ch01-2.doc
ch02-1.doc
Tin trnh chy trong Foreground, kt qu ca n c hng trc tip trn mn hnh ca ti v
nu lnh ls mun bt k u vo no, n i t bn phm.
Trong khi mt chng trnh ang chy trong Foreground v cn mt khong thi gian di, chng ta
khng th chy bt k lnh khc (bt u mt tin trnh khc) bi v dng nhc khng c sn ti khi
chng trnh ang chy kt thc tin trnh v thot ra.
Tin trnh Background trong Unix/Linux

Background Process chy m khng c kt ni vi bn phm ca bn. Nu tin trnh
Background yu cu bt c u vo t bn phm, n i.
Li th ca chy mt chng trnh trong Background l bn c th chy cc lnh khc; bn khng
phi i ti khi n kt thc bt u mt tin trnh mi!
Cch n gin nht bt u mt tin trnh Background l thm du v (&) ti phn cui ca
lnh.
$ls ch*.doc &
iu ny cng hin th tt c cc file m tn bt u vi ch v kt thc vi .doc:

ch01-1.doc
ch010.doc
ch02.doc
ch03-2.doc
ch04-1.doc
ch040.doc
ch05.doc
ch06-2.doc
ch01-2.doc
ch02-1.doc
Ti y, nu lnh ls mun bt k u vo no (m n khng), n tin vo trng thi dng ti khi

bn di chuyn n vo trong Foreground v cung cp cho n d liu t bn phm.
Page 42
Dng u tin cha cc thng tin v Background Process - s cng vic (job number) v Process
ID. Bn cn bit v Job number thao tc n gia Background v Foreground.
Nu bn nhn phm Enter by gi, bn nhn thy nh sau:
[1]
Done
ls ch*.doc &
Dng u tin ni cho bn rng lnh ls trong Background Process hon thnh mt cch thnh
cng. Dng th hai l mt dng nhc cho mt lnh khc.
Lit k cc tin trnh ang chy trong Unix/Linux

N l d dng quan st cc tin trnh ca bn bng cch chy lnh ps (vit tt ca process
status) nh sau:
$ps
PID
TTY
TIME
CMD
18358
ttyp3
00:00:00
sh
18361
ttyp3
00:01:31
abiword
18789
ttyp3
00:00:00
ps
Mt trong nhng flag c s dng cho ps l -f (vit tt ca full), m cung cp nhiu thng tin nh
v d di y:
$ps -f
UID
PID
PPID C STIME
TTY
TIME CMD
amrood
6738 3662 0 10:23:03 pts/6 0:00 first_one
amrood
6739 3662 0 10:22:54 pts/6 0:00 second_one
amrood
3662 3657 0 08:10:53 pts/6 0:00 -ksh
amrood
6892 3662 4 10:51:50 pts/6 0:00 ps -f
Di y l s miu t ca tt c cc file c hin th bi lnh ps -f.
Ct
Miu t
UID
ID ngi s dng m tin trnh ny thuc s hu (ngi chy n).
Page 43
PID
Process ID.
PPID
Process ID gc (ID ca tin trnh m bt u n).
CPU s dng ca tin trnh.
STIME
Thi gian bt u tin trnh.
TTY
Kiu terminal lin kt vi tin trnh.
TIME
Thi gian CPU b s dng bi tin trnh.
CMD
Lnh m bt u tin trnh ny.
C nhng chc nng khc m c th c s dng song song vi lnh ps:
Chc nng
Miu t
-a
Ch thng tin v tt c ngi s dng.
-x
Ch thng tin v cc tin trnh m khng c terminal.
-u
Ch thng tin thm vo nh chc nng -f.
-e
Hin th thng tin c m rng.
Dng tin trnh trong Unix/Linux

Kt thc mt tin trnh c th c thc hin theo vi cch khc nhau. Thng thng, t mt lnh
console-based, gi CTRL + C bng g phm (mc nh l k t ngt) s hy lnh. N lm vic khi
tin trnh ang chy trong ch Foreground.
Nu mt tin trnh ang chy trong ch Background, th u tin bn cn nhn ID cng vic (job
ID) bng cch s dng lnh ps v sau bn c th s dng lnh kill kh tin trnh nh sau:
$ps -f
Page 44
PPID C STIME
TTY
UID
PID
TIME CMD
amrood
6738 3662 0 10:23:03 pts/6 0:00 first_one
amrood
6739 3662 0 10:22:54 pts/6 0:00 second_one
amrood
3662 3657 0 08:10:53 pts/6 0:00 -ksh
amrood
6892 3662 4 10:51:50 pts/6 0:00 ps -f
$kill 6738
Terminated
y lnh kill s kt thc tin trnh first_one. Nu mt tin trnh thng b qua mt lnh kill, bn
c th s dng kill -9 theo sau bi Process ID nh sau:
$kill -9 6738
Terminated
Tin trnh m v tin trnh con trong Unix/Linux

Mi mt tin trnh Unix c hai ID c gn cho n: Process ID (pid) v Parent Process ID (ppid).
Mi tin trnh trong h thng c mt Parent Process (gc).
Hu ht cc lnh m bn chy c Shell nh l m ca n. Kim tra v d ps -f m ti y lnh ny
lit k c Process ID v Process ID gc.
Tin trnh Zombie v Orphan

Thng thng, khi mt tin trnh con b kh, Parent Process c thng bo thng qua k hiu
SIGCHLD. Sau , tin trnh gc c th thc hin mt vi cng vic khc hoc bt u li tin trnh
con nu cn thit. Tuy nhin, i khi Parent Process b kh trc khi tin trnh con ca n b kh.
Trong trng hp ny, Parent Process ca tt c cc tin trnh, tin trnhinit, tr thnh PPID mi
(Process ID m). i khi nhng tin trnh ny c gi l tin trnh Orphan.
Khi mt tin trnh b kh, danh sch lit k ps c th vn ch tin trnh vi trng thi Z. y l trng
thi Zombie, hoc tin trnh khng tn ti. Tin trnh ny b kh v khng c s dng. Nhng
tin trnh ny khc vi tin trnh orphan. N l nhng tin trnh m chy hon thnh nhng vn
c mt cng vo trong bng tin trnh.
Tin trnh Daemon trong Unix/Linux

Daemon l cc Background Process lin quan ti h thng m thng chy vi quyn hn truy
cp ca root v cc dch v yu cu t tin trnh khc.
Page 45
Mt tin trnh deamon khng c terminal iu khin. N khng th m /dev/tty. Nu bn thc hin
mt ps-ef v quan st vo trng tty, tt c deamon s c mt du ? cho tty.
r hn, mt deamon ch l mt tin trnh m chy trong Background, thng i cho ci g
xy ra m n c kh nng lm vic vi, ging nh my in deamon ang i cc lnh in.
Nu bn c mt chng trnh m cn thc hin mt tin trnh di, th sau gi tr ca n to
mt deamon v chy n trong Background.
Lnh top trong Unix/Linux

Lnh top l mt cng c rt hu ch cho vic hin th nhanh cc tin trnh c sp xp bi cc
tiu chun a dng.
N l mt cng c chn on tng tc m cp nht thng xuyn v hin th thng tin v b nh
vt l v b nh o, s s dng CPU, .
Di y l c php n gin chy lnh top v quan st kt qu thng k ca s s dng CPU
bng cc tin trnh khc nhau:
$top
Job ID vi Process ID trong Unix/Linux

Tin trnh Background v Foreground thng c thao tc thng qua Job ID. S ny khc vi
Process ID v c s dng bi v n ngn hn.
Ngoi ra, mt cng vic c th bao gm nhiu tin trnh ang chy trong seri hoc ti cng mt thi
gian, song song, v th s dng Job ID l d dng hn theo di cc tin trnh ring l.
Cc tin ch giao tip mng trong Unix

Khi bn lm vic trong mi trng phn phi th khi bn cn giao tip vi nhng ngi s dng
t xa v bn cng cn truy cp vo cc thit b Unix t xa.
C mt vi tin ch Unix m c bit hu ch cho ngi s dng giao tip trong mt mi trng
phn phi, kt ni mng. Chng ny lit k vi tin ch trong s chng.
Tin ch ping trong Unix/Linux

Page 46
Lnh ping gi mt yu cu echo ti mt host c sn trn mng. S dng lnh ny bn c th kim

tra nu host t xa ca bn ang phn hi tt hoc khng.
Lnh ping hu ch v:
Theo di v phn tch tnh n lp phn cng v cc vn v phn mm.
Xc nh trng thi ca mng v cc host ngoi a dng khc.
Kim tra, nh gi v qun l mng.
C php trong Unix/Linux

Sau y l c php n gin s dng lnh ping:
$ping hostname hoc ip-address
Lnh trn s bt u in mt phn hi sau mi giy. thot khi lnh ny bn c th kt thc n

bng cch nhn t hp phm CTRL + C.
V d trong Unix/Linux:
Di y l v d kim tra tnh sn sng ca mt host c trn mng:
$ping google.com
PING google.com (74.125.67.100) 56(84) bytes of data.
64 bytes from 74.125.67.100: icmp_seq=1 ttl=54 time=39.4 ms
--- google.com ping statistics --22 packets transmitted, 22 received, 0% packet loss, time 21017ms
rtt min/avg/max/mdev = 38.867/39.334/39.900/0.396 ms
$
Nu mt host khng tn ti th khi n s chy mt ci g ging nh sau:

$ping giiiiiigle.com
ping: unknown host giiiiigle.com
Page 47
Tin ch ftp trong Unix/Linux

y ftp l vit tt ca File Transfer Protocol. Tin ch ny gip bn ti ln v ti v (upload v
download) file ca bn t mt my tnh sang mt my tnh khc.
Tin ch ftp c b thit lp ring ca n trong Unix nh cc lnh m cho php bn thc hin cc
cng vic nh:
Kt ni v ng nhp ti mt host t xa.
iu hng cc th mc;
Lit k ni dung th mc;
t v nhn cc file;
Truyn ti cc file dng ASCII, EBCDIC hoc nh phn.

Di y l c php n gin s dng lnh ftp:
$ftp hostname hoc ip-address
Lnh trn s nhc bn nhp ID ng nhp v mt khu. Mt khi bn xc nhn xong, bn c th

truy cp trn th mc chnh ca ti khon ng nhp v bn c th thc hin cc lnh khc nhau.
Mt s lnh hu ch c lit k sau y:
Lnh
Miu t
put filename
Ti mt filename ln t thit b ni b ln thit b t xa
get filename
Ti mt filename xung t thit b t xa xung thit b ni b
mput file list
Ti nhiu hn mt file t thit b ni b ln thit b t xa.
Page 48
Ti xung nhiu hn mt file t thit b t xa xung thit b ni b.
mget file list
Tt dng nhc lnh, theo mc nh bn s c nhc ti ln hoc ti
prompt off
xung cc movie bng cch s dng lnh mput hoc mget.
prompt on
Bt dng lnh nhc.
dir
Lit k tt c cc file c trong th mc hin ti ca thit b t xa.
cd dirname
Thay i th mc ti dirname trn thit b t xa.
lcd dirname
Thay i th mc ti dirname trn thit b ni b.
quit
Thot ra t s ng nhp hin ti .
N nn c ghi ch rng cc file s c download hoc upload ti hoc t cc th mc hin ti.

Nu bn mun upload cc file ca bn trong mt th mc ring bit th khi u tin bn thay i
ti th mc v sau ti file c yu cu ln.
Di y l v d minh ha v mt s lnh:
$ftp amrood.com
Connected to amrood.com.
220 amrood.com FTP server (Ver 4.9 Thu Sep 2 20:35:07 CDT 2009)
Name (amrood.com:amrood): amrood
331 Password required for amrood.
Password:
230 User amrood logged in.
ftp> dir
200 PORT command successful.
150 Opening data connection for /bin/ls.
total 1464
drwxr-sr-x
3 amrood
group
1024 Mar 11 20:04 Mail
drwxr-sr-x
2 amrood
group
1536 Mar
3 18:07 Misc
Page 49
drwxr-sr-x
5 amrood
group
512 Dec
7 10:59 OldStuff
drwxr-sr-x
2 amrood
group
1024 Mar 11 15:24 bin
drwxr-sr-x
5 amrood
group
3072 Mar 13 16:10 mpl
-rw-r--r--
1 amrood
group
drwxr-sr-x
3 amrood
group
512 Jan
drwxr-sr-x
3 amrood
group
512 Feb 10 10:17 pvm3
209671 Mar 15 10:57 myfile.out

5 13:32 public
226 Transfer complete.

ftp> cd mpl
250 CWD command successful.
ftp> dir
150 Opening data connection for /bin/ls.
total 7320
-rw-r--r--
1 amrood
group
1630 Aug
8 1994
dboard.f
-rw-r-----
1 amrood
group
4340 Jul 17 1994
vttest.c
-rwxr-xr-x
1 amrood
group
-rw-r--r--
1 amrood
group
1648 Aug
-rwxr-xr-x
1 amrood
group
4019 Feb 14 16:26 fix.c
525574 Feb 15 11:52 wave_shift

5 1994
wide.list

ftp> get wave_shift
150 Opening data connection for wave_shift (525574 bytes).
528454 bytes received in 1.296 seconds (398.1 Kbytes/s)
ftp> quit
221 Goodbye.
$
Tin ch telnet trong Unix/Linux

Nhiu khi bn s cn kt ni ti mt thit b Unix t xa v lm vic trn thit b vi ch iu
khin t xa. Telnet l mt tin ch m cho php mt ngi s dng my tnh ti mt site to mt s
kt ni, ng nhp v sau thc hin cng vic trn my tnh ti mt site khc.
Page 50
Mt khi bn ng nhp bng cch s dng telnet, bn c th thc hin tt c cc hot ng trn
thit b kt ni t xa. Di y l v d v telnet:
C:>telnet amrood.com
Trying...
Connected to amrood.com.
Escape character is '^]'.
login: amrood
amrood's Password:
*****************************************************
*
WELCOME TO AMROOD.COM
*****************************************************
Last unsuccessful login: Fri Mar

Last login: Wed Mar
3 12:01:09 IST 2009
8 18:33:27 IST 2009 on pts/10
do your work }
$ logout
Connection closed.
C:>
Tin ch finger trong Unix/Linux

Lnh finger hin th thng tin v nhng ngi s dng trn mt host cho. Host c th l ni b
hoc t xa.
Finger c th bt lc trn h thng khc v l do bo mt.
Di y l c php n gin s dng lnh finger:
Page 51
Kim tra tt c cc ngi s dng ng nhp trn thit b ni b nh sau:

$ finger
Login
Name
Tty
amrood
Idle
pts/0
Login Time
Office
Jun 25 08:03 (62.61.164.115)
Nhn thng tin v mt ngi s dng ring bit c trn thit b ni b:

$ finger amrood
Login: amrood
Name: (null)
Directory: /home/amrood
Shell: /bin/bash
On since Thu Jun 25 08:03 (MST) on pts/0 from 62.61.164.115

No mail.
No Plan.
Kim tra tt c ngi s dng ng nhp trn thit b t xa nh sau:

$ finger @avtar.com
Login
Name
amrood
Tty
pts/0
Idle
Login Time
Office
Jun 25 08:03 (62.61.164.115)
Nhn thng tin v mt ngi s dng ring bit c trn thit b t xa nh sau:
$ finger amrood@avtar.com
Login: amrood
Name: (null)
Directory: /home/amrood
Shell: /bin/bash
On since Thu Jun 25 08:03 (MST) on pts/0 from 62.61.164.115

No mail.
No Plan.
Trnh son tho vi trong Unix

C rt nhiu cch chnh sa cc file trong Unix v i vi ti, mt trong nhng cch tt nht l
s dng B (Trnh) son tho hng mn hnh vi. B son tho ny cho bn c th chnh sa cc
dng trong ni dung vi cc dng khc trong file.
Ngy nay bn s tm thy mt phin bn c nng cp ca B son tho vi m c gi lVIM.
VIM l vit tt ca Vi Improved.
Page 52
B son tho vi thng c cn nhc l tiu chun thc quyn trong B son tho Unix bi v:
N thng c sn trn tt c cc phin bn ca h thng Unix;
Trnh thc hin ca n tng t nh bng;
N yu cu rt t ngun cho n;
N thn thin hn cc B son tho khc nh ed hoc ex.
Bn c th s dng B son tho vi chnh sa mt file ang hin hu hoc to mt file mi t

scratch. Bn cng c th s dng B son tho ny ch c mt file vn bn.
Bt u chy B son tho vi trong Unix/Linux

C nhng cch sau m bn c th s dng bt u chy B son tho vi:
Lnh
vi filename
Miu t
To mt file mi nu n khng tn ti, nu khng th m mt file
ang tn ti.
vi -R filename
M mt file ang tn ti trong ch ch c.
view filename
M mt file ang tn ti trong ch ch c.
Di y l v d to mt file mi testfile nu n khng tn ti trong th mc lm vic hin

ti:
$vi testfile
Bn c th quan st kt qu ging nh sau trn mn hnh:

|
~
~
~
~
~
Page 53
~
~
~
~
~
~
~
"testfile" [New File]
Bn s ch mt du ng (~) trn mi dng con tr. Du ng ny i din cho mt dng cha

c s dng. Nu mt dng khng bt u vi du ng v xut hin khong trng, c th l mt
khong trng, tab, dng mi hoc mt vi k t khng nhn thy.
V th by gi bn m mt file bt u n. Trc khi thc hin cc tin trnh xa hn, chng
ta cng tm hiu mt vi khi nim quan trng c gii thch bn di.
Cc ch hot ng trong Unix/Linux:

Trong khi lm vic vi b son vi, bn s tnh c theo hai ch sau:
1. Ch lnh (Command mode): Ch ny cho bn c th thc hin cc nhim v hnh
chnh nh lu file, chy lnh, di chuyn con tr, ct v dn cc dng hoc t, v tm kim
v i v tr. Trong ch ny, bt c ci g bn g vo c h thng bin dch (hiu) nh
mt lnh.
2. Ch chn (Insert mode): Ch ny cho bn c th chn vn bn vo trong file. Mi
th m c g vo trong ch ny c h thng hiu nh l mt u vo v cui cng
n t vo trong file.
B son tho vi thng bt u vi ch lnh. nhp vn bn, bn phi trong ch chn.
vo ch chn, n gin bn ch cn g i. thot khi ch chn, nhn phmEsc, m s t
bn quay tr li ch lnh.
Gi : Nu bn khng chc chn v ch m bn ang trong, nhn phm Esc hai ln, v sau
bn s trong ch lnh. Bn m mt file bng cch s dng B son tho vi v bt u g
mt vi k t, sau bn vo ch lnh thy s khc nhau.
Thot khi vi trong Unix/Linux

Page 54
Lnh thot khi B son tho vi l :q. Mt khi ang trong ch lnh, g du hai chm v q v
du ! theo sau. Nu file ca bn c chnh sa theo cch no , B son tho s cnh bo
bn v iu ny v khng cho bn thot khi n. b qua thng bo ny, lnh thot khi vi
m khng lu cc chnh sa l :q!. Lnh ny gip bn thot khi vi m khng lu bt c s thay
i no m bn to ra ti file.
Lnh lu ni dung ca B son tho vi l :w. Bn c th kt ni lnh trn vi lnh quit, hoc :wq
v du quay li !.
Cch d nht lu cc thay i v thot khi vi l lnh ZZ. Khi bn ang trong ch lnh, g ZZ
v n s lm vic tng t nh lnh :wq.
Bn c th xc nh tn cc file khc nhau lu bng cch xc nh tn file sau :w. V d, nu
bn mun lu file bn ang lm vic thnh mt file khc c tn l filename2, bn s g :wfilename2
v du !. Bn t mnh th nh.
Di chuyn trong mt file trong Unix/Linux

di chuyn xung quanh trong mt file m khng nh hng n vn bn, bn phi trong ch
lnh (nhn phm Esc hai ln). Ti y c mt vi lnh m bn c th s dng di chuyn xung
quanh mt k t ti cng mt thi gian.
Lnh
Miu t
Di chuyn con tr ln trn mt dng.
Di chuyn con tr xung mt dng.
Di chuyn con tr sang tri mt k t.
Di chuyn con tr sang phi mt k t.
C hai im quan trng m bn cn ghi nh:
B son tho vi l phn bit ch hoa v thng, v th bn cn ch khi vit ch hoa trong
khi s dng lnh.
Page 55
Hu ht cc lnh trong vi c th c m u bng s ln bn mun hnh ng xy ra. V

d, 2j l di chuyn con tr xung 2 dng.
C nhiu cch khc di chuyn trong mt file trong vi. Nh rng bn phi trong ch lnh (nhn
Esc hai ln). Di y l mt bng lit k cc lnh khc m bn c th s dng di chuyn xung
quanh file:
Lnh
Miu t
0 or |
t v tr con tr ti u dng.
t v tr con tr cui dng.
t v tr con tr t tip theo.
t v tr con tr t trc.
t v tr con tr u cu vn hin ti.
t v tr con tr u cu vn k tip.
Di chuyn ti phn cui ca t c gii hn khong trng.
Di chuyn ti on vn sau.
Di chuyn v on vn trc.
[[
Di chuyn ti khu vc sau.
]]
Di chuyn v khu vc trc.
n|
Di chuyn ti ct n trong dng hin ti.
1G
Di chuyn ti dng u tin ca file.
Page 56
Di chuyn ti dng cui cng ca file.
nG
Di chuyn ti dng th n ca file.
:n
Di chuyn ti dng th n ca file.
fc
Di chuyn thun tin ti c
Fc
Di chuyn ngc li ti c
Di chuyn ti u ca mn hnh.
nH
Di chuyn ti dng th n tnh t u ca mn hnh.
Di chuyn ti gia mn hnh.
Di chuyn ti cui cng mn hnh.
nL
Di chuyn ti dng th n tnh t cui cng ca mn hnh.
:x
Du hai chm theo sau bi mt s s t v tr ca con tr trn dng

s x
Cc lnh iu khin trong Unix/Linux

Cc lnh di y hu dng m bn c th s dng song song vi phm control:
Lnh
Miu t
CTRL+d
Di chuyn tin ti 1/2 mn hnh.
CTRL+d
Di chuyn tin ti 1/2 mn hnh.
CTRL+f
Di chuyn tin ti mt mn hnh y .
Page 57
CTRL+u
Di chuyn ngc v sau 1/2 mn hnh.
CTRL+b
Di chuyn ngc v sau mt mn hnh.
CTRL+e
Di chuyn mn hnh ln mt dng.
CTRL+y
Di chyn mn hnh xung mt dng.
CTRL+u
Di chuyn mn hnh ln 1/2 trang.
CTRL+d
Di chuyn mn hnh xung 1/2 trang.
CTRL+b
Di chuyn mn hnh ln mt trang.
CTRL+f
Di chuyn mn hnh xung mt trang.
CTRL+I
Ko mn hnh ngc li.
Chnh sa file trong Unix/Linux

chnh sa file, bn cn trong ch chn. C nhiu cch vo ch chn t ch lnh.
Lnh
Miu t
Chn vn bn trc v tr con tr hin ti.
Chn vn bn phn u dng hin ti.
Chn vn bn sau v tr con tr hin ti.
Chn vn bn ti phn cui ca dng hin ti.
To mt dng mi nhp vn bn di v tr con tr hin ti.
To mt dng mi nhp vn bn trn v tr con tr hin ti.
Page 58
Xa cc k t trong Unix/Linux
Di y lit k cc lnh quan trng m c th c s dng xa cc k t v cc dng trong
mt file m:
Lnh
Miu t
Xa mt k t di v tr con tr hin ti.
Xa mt k t trc v tr con tr hin ti.
dw
Xa t v tr con tr hin ti ti t k tip.
d^
Xa t v tr con tr hin ti ti phn bt u ca dng.
d$
Xa t v tr con tr hin ti ti phn cui ca dng.
Xa t v tr con tr hin ti ti phn cui ca dng hin ti.
dd
Xa dng m con tr hin ti ang trn.
Nh cp trn, hu ht cc lnh trong vi c th c t trc bi s ln bn mun hnh

ng xy ra. V d, 2x s xa 2 k t di v tr con tr hin ti v 2dd s xa 2 dng m con tr
ang trn hin ti.
Chng ti ngh bn thc hnh cc lnh trn nhiu ln trc khi thc hin cc tin trnh phc tp
hn.
Cc lnh thay i trong Unix/Linux

Bn cng c kh nng thay i cc k t, cc t,, hoc dng trong vi m khng cn xa chng.
Di y l cc lnh lin quan:
Lnh
Miu t
cc
G b ni dung ca dng, lm cho bn ri khi ch chn.
Page 59
cw
Thay i t m con tr ang ti , t v tr con tr ti v tr ch w thng

cui cng ca t.
i v tr ca k t di v tr con tr. Vi tr li ch lnh sau khi s i v tr
ny c thc hin xong.
Vit nhiu k t bt u vi k t hin ti di con tr. Bn phi s dng
phm Esc dng vic vit ny.
i v tr ca k t hin ti vi k t m bn g vo. Sau , bn b ri khi ch
chn.
Xa dng m con tr ang trn v thay i bng mt on vn bn mi. Sau
khi vn bn mi c nhp, vi vn gi nguyn ch chn.
Cc lnh sao chp v dn trong Unix/Linux

Bn c th sao chp cc dng hoc cc t t mt v tr v sau bn dn chng ti v tr khc
bng cch s dng cc lnh sau:
Lnh
Miu t
yy
Sao chp dng hin ti.
yw
Sao chp t hin ti t k t ch thng w con tr trn ti phn cui

ca t.
Dn bn sao sau v tr con tr.
Dn bn sao trc v tr con tr.
Cc lnh nng cao trong Unix/Linux

Di y lit k mt s lnh nng cao m lm n gin ha vic chnh sa thng ngy v mang
li nhiu hiu qu hn trong vic s dng vi:
Page 60
Lnh
Miu t
Nhp dng hin ti vi dng k tip.
<<
Di chuyn dng hin ti sang tri mt rng shift.
>>
Di chuyn dng hin ti sang phi mt rng shift.
Chuyn kiu ca k t di v tr con tr (VD: ch hoa thnh ch thng ).
^G
Nhn Ctrl+G cng mt lc ch trng thi v tn file hin ti.
Hi phc dng hin ti tr v trng thi trc khi con tr vo dng .
Undo cc thay i va thc hin vi file. Nhp u ln na s redo s thay

i.
Nhp dng hin ti vi dng k tip.
:f
Hin th v tr hin ti ca file trong % v tn file, tng s file.
:f filename
t li tn hin ti ca file.
:w filename
Vit tn file
:e filename
M mt file khc vi tn ca n.
:cd dirname
Thay i th mc lm vic hin ti ti th mc dirname.
:e #
S dng chuyn i gia hai file m.
:n
Trong trng hp bn m nhiu file s dng vi, bn s dng :n ti file

k tip trong seri cc file .
Page 61
Trong trng hp bn m nhiu file s dng vi, bn s dng :p ti file
:p
pha trc trong seri file .

Trong trng hp bn m nhiu file s dng vi, bn s dng :N ti file
:N
pha trc trong seri file .
:r file
c file v chn n sau dng hin ti.
:nr file
c file v chn n sau dng th n.
Tm kim t v k t trong Unix/Linux

B son tho vi c hai loi tm kim: chui v k t. tm kim chui, lnh / v ? c s dng.
Khi bn bt u nhng lnh ny, lnh va c nhp vo s c ch cui cng ca dng, ti
bn nhp mt chui c th m bn mun tm tm kim n.
Hai lnh ny ch khc nhau phng din ni m n din ra:
Lnh / tm kim theo chiu thun v pha trc trong mt file.
Lnh ? tm kim theo chiu ngc li v pha sau trong mt file.
Cc lnh n v N tng ng lp li lnh tm trc theo cng cch tm hoc theo hng ngc li.
Mt vi k t c ngha quan trng trong khi s dng lnh tm kim v c t trc bi mt du
\ tr thnh mt phn ca biu thc cn tm.
K t
Miu t
Tm ti u ca dng. (S dng ti phn bt u ca mt biu thc tm
kim.)
Kt ni vi mt k t n.
Kt ni vi 0 hoc nhiu k t trc.
Cui ca dng. (s dng ti phn cui ca biu thc tm kim.)
Page 62
<
>
Bt u mt thit lp ca biu thc kt ni hoc khng kt ni.

t biu thc tm kim tch khi du cho ngc \ tm phn cui hoc
phn u ca t.
t biu thc tm kim tch khi du cho ngc \ tm phn cui hoc
phn u ca t.
Hot ng tm kim k t tm kim trong mt dng tm mt k t c nhp sau lnh. Lnh f v

F ch tm kim cho mt k t trn dng hin ti. Lnh f tm kim thun v pha trc v F tm kim
ngc v pha sau v con tr di chuyn ti v tr ca k t c tm thy.
Lnh t v T ch tm kim mt k t trn dng hin ti, nhng vi t, con tr di chuyn ti v tr trc
k t, v T tm kim dng v pha ngc li ti v tr sau k t.
Cc lnh set trong Unix/Linux

Bn c th to thay i mn hnh hin th ca vi bng cch s dng lnh :set. s dng nhng
lnh ny, bn phi vo ch lnh sau g :set theo sau bi mt trong cc chc nng sau:
Lnh
Miu t
:set ic
B qua kiu ch (ch hoa, thng) khi tm kim.
:set ai
Thit lp ch tht vo u dng t ng.
:set noai
khng t ch tht vo u dng t ng.
:set nu
Hin th cc dng vi s dng trn cnh tri.
:set sw
:set ws
Thit lp rng ca im dng tab ca mt phn mm. V d bn c th thit

lp mt rng shift l 4 vi lnh ny :set sw=4
Nu wrapscan c thit lp, nu t khng c tm thy ti phn cui cng
ca file, n s c gng tm kim ti phn bt u.
Page 63
Nu chc nng ny c mt gi tr ln hn 0, B son tho s t ng bao l k

:set wm
t (word wrap). V d, thit lp l bao ti hai k t, bn s g th ny :set

wm=2
:set ro
Thay i kiu file thnh ch c (read only)
:set term
In kiu terminal.
:set bf
B qua vic iu khin k t t u vo.
Chy cc lnh trong Unix/Linux

B son tho vi c kh nng chy cc lnh t trong B son tho. chy mt lnh, bn ch cn
tin vo ch lnh v nhp lnh :!.
V d, nu bn mun kim tra mt file c tn ti khng trc khi bn c gng lu file vi tn
cho, bn c th nhp :! ls v bn s thy kt qu ca lnh ls trn mn hnh.
Khi bn nhn bt k phm no, bn c quay tr li khu vc vi ca bn.
Thay th vn bn trong Unix/Linux

Lnh thay th (:s/) cho bn c th nhanh chng i cc t hoc nhm t trong file ca bn. Di
y l c php n gin:
:s/search/replace/g
K t g i din cho ton cu (globally). Kt qu ca lnh ny l tt c cc s kin din ra trn

dng m con tr ti c thay i.
Cc im quan trng trong Unix/Linux:

Di y l cc im quan trng gip bn thnh cng khi s dng vi:
Bn phi trong ch lnh s dng cc lnh. (Nhn phm Esc hai ln vo bt c lc no

m bo bn trong ch lnh).
Bn phi cn thn s dng cc kiu ch (hoa v thng) cho tt c cc lnh.
Bn phi trong ch chn nhp vn bn.
Page 64
Shell l g?
Shell cung cp cho bn mt giao din vi h thng Unix. N thu thp input t bn v chy cc
chng trnh trn c s u vo . Khi mt chng trnh hon thnh, n hin th kt qu (output)
ca chng trnh .
Mt Shell l mt mi trng trong chng ta c th chy cc lnh, cc chng trnh v Shell
script. C cc phin bn khc nhau ca Shell, m ch khc nhau t phin bn ca h iu hnh.
Mi phin bn ca Shell c b thit lp cc lnh v hm c tha nhn ring ca n.
Dng nhc lnh Shell trong Unix/Linux

Dng nhc lnh, $, c thng bo bi Shell. Trong khi dng nhc c hin th, bn c th nhp
mt lnh.
Shell c u vo bn nhp sau khi bn nhn Enter. N xc nh lnh m bn mun chy bi nhn
vo t u tin trong phn nhp ca bn. Mt t l mt tp hp khng gin on ca cc k t.
Cc khong trng v tab phn cch cc t.
Di y l mt v d n gin ca lnh date m hin th ngy v thi gian hin ti:
$date
Thu Jun 25 08:30:19 MST 2009
Bn c th ty chnh dng nhc lnh ca mnh bng cch s dng bin mi trng PS1 c gii
thch trong chng Mi trng lm vic.
Cc kiu Shell trong Unix/Linux

Trong Unix c hai kiu Shell chnh:
1. Kiu Bourne Shell. Nu bn ang s dng mt Bourne Shell, dng nhc lnh mc nh l k
t $.
2. Kiu C Shell. Nu bn ang s dng kiu C Shell, dng nhc mc nh l k t %.
Trong kiu Bourne Shell li c cc kiu ph khc nh sau:
Bourne Shell (sh)
Korn Shell (ksh)
Page 65
Bourne Again Shell ( bash)
POSIX Shell ( sh)
Trong kiu C Shell c cc kiu ph khc:
C Shell (csh)
TENEX/TOPS C Shell ( tcsh)
Cc Unix Shell u tin c vit vo gia thp k 1970 bi Stephen R. Bourne trong khi ng ta
ang lm vic ti phng th nghim AT&T Bell Labs New Jersey.
Bourne Shell l Shell u tin xut hin trn h thng Unix, v th n c cp n nh l the
Shell.
Bourne Shell thng c ci t nh l /bin/sh trn hu ht cc phin bn Unix. V l do ny, n
l Shell c chn vit script d dng trn cc phin bn khc nhau ca Unix.
Trong chng ny, chng ta cp n hu ht cc khi nim Shell trn c s Bourne Shell.
Shell Scripts trong Unix/Linux

Khi nim c bn ca mt Shell script l mt danh sch cc lnh, m c lit k theo th t thi
hnh. Mt Shell script tt s c cc li bnh (comment), ng trc bi du #, miu t cc bc.
C cc kim tra iu kin, nh gi tr A ln hn gi tr B, cc loop cho php chng ta x l mt
lng ln d liu, cc file c v lu gi d liu v cc bin c v lu gi liu, v script c
th bao gm cc hm.
Shell script v cc hm u c thng dch. iu ny c ngha l chng khng c bin dch.
Chng ta chun b vit nhiu script trong cc phn hng dn tip theo. N c th l mt file vn
bn n gin trong chng ta t tt c cc lnh v mt s cu trc cn thit m ni cho mi
trng Shell v ci g c lm v khi no c thc hin.
V d v script trong Unix/Linux

Gi s chng ta to mt test.sh. Ghi nh rng tt c cc script nn c ui m rng .sh. Trc khi
bn thm bt k ci g ti script ca bn, bn cn bo h thng rng mt Shell script chun b c
bt u. Vic ny c thc hin bng cch s dng cu trc shebang. V d:
Page 66
#!/bin/sh
Lnh ny ni cho h thng rng cc lnh theo sau c chy bi Bourne Shell. N c gi l mt
shebang bi v k hiu # c gi l mt hash v k hiu ! c gi l mt bang.
to mt script cha cc lnh ny, u tin bn t dng shebang v sau thm cc lnh:
#!/bin/bash
pwd
ls
Cc li bnh Shell trong Unix/Linux

Bn c th t cc Shell Comment trong script nh sau:
#!/bin/bash
# Author : Zara Ali

# Copyright (c) Tutorialspoint.com
# Script follows here:
pwd
ls
By gi bn lu ni dung trn v lm cho script ny chy nh sau:

$chmod +x test.sh
By gi bn c mt Shell script ca mnh sn sng chy nh sau:

$./test.sh
iu ny to ra kt qu sau:
/home/amrood
index.jsp
unix-basic_utilities.jsp
unix-directories.jsp
test.sh
unix-communication.jsp
unix-environment.jsp
Ghi ch: chy bt c chng trnh no ca bn c trong th mc hin ti, bn nn chy bng
cch s dng ./program_name
Page 67
Shell script m rng trong Unix/Linux

Shell script c mt vi cu trc c yu cu m ni cho mi trng Shell v iu g lm v khi
no thc hin n. Tt nhin, hu ht script y phc tp hn nhng script gii thiu trn.
Shell l mt ngn ng chng trnh thc s, y vi cc bin, cc cu trc iu khin v . D
n c phc tp bao nhiu, th tuy nhin, n vn ch l mt danh sch lnh c thc thi mt cch
lin tc.
Cc script sau s dng lnh read m nhn u vo t bn phm v gn gi tr cho n vi bin
PERSON v cui cng in n trn bin STDOUT.
#!/bin/sh
# Author : Zara Ali

# Copyright (c) Tutorialspoint.com
# Script follows here:
echo "What is your name?"

read PERSON
echo "Hello, $PERSON"
Di y l chy mu ca script trn:

$./test.sh
What is your name?
Zara Ali
Hello, Zara Ali
$
S dng cc bin trong Shell

Mt bin l mt chui k t t chng ta gn mt gi tr. Gi tr c gn c th l mt s, vn
bn, tn file, thit b hoc bt k kiu no khc ca d liu.
Mt bin l khng g khc ngoi mt con tr tr ti d liu thc. Shell cho php bn to, gn, v
xa cc bin.
Page 68
Cc tn bin trong Unix/Linux

Tn ca mt bin c th ch cha cc k t (a ti z hoc t A ti Z), cc s (t 0 ti 9), hoc k
hiu gch di ( _).
Theo quy c, cc bin Unix shell s c tn ca chng trong ch in hoa.
V d di y v mt tn bin hp l.
_ALI
TOKEN_A
VAR_1
VAR_2
Sau y l v d v cc tn bin khng hp l:

2_VAR
-VARIABLE
VAR1-VAR2
VAR_A!
L do l bn khng th s dng cc k t khc nh !, *, hoc - , bi v cc k t ny c ngha c

bit i vi shell.
nh ngha cc bin trong Unix/Linux

Cc bin c nh ngha nh sau:
variable_name=variable_value
V d:
NAME="Zara Ali"
V d trn nh ngha bin Name v gn gi tr Zara Ali cho n. Cc bin theo kiu ny c gi l
cc bin v hng (scala). Mt bin v hng ch c th gi mt gi tr ti mt thi im.
Shell cho php bn gi bt k gi tr no bn mun trong mt bin. V d:
VAR1="Zara Ali"
Page 69
VAR2=100
Truy cp cc gi tr trong Unix/Linux

truy cp cc gi tr c gi trong mt bin, t trc tn bin vi k hiu ( $):
V d, script sau s truy cp vo gi tr ca bin NAME c nh ngha v s in n trn
STDOUT:
#!/bin/sh
NAME="Zara Ali"
echo $NAME
N s to ra kt qu sau:
Zara Ali
Cc bin ch c (read-only) trong Unix/Linux

Shell cung cp mt cch nh du cc bin nh read-only bng cch s dng lnhreadonly.
Sau khi mt bin c nh du read-only, gi tr ca n khng th thay i.
V d, script sau s li trong khi c gng thay i gi tr ca bin NAME.
#!/bin/sh
NAME="Zara Ali"
readonly NAME
NAME="Qadiri"
N s to kt qu sau:
/bin/sh: NAME: This variable is read only.
Xa mt bin trong Unix/Linux

Xa mt bin ni cho shell g b bin t danh sch cc bin m n theo di. Mt khi bn
xa mt bin, bn s khng th truy cp vo gi tr lu gi trong bin .
Di y l c php xa mt bin c nh ngha bng cch s dng lnh unset:
Page 70
unset variable_name
Lnh trn s xa gi tr ca mt bin c nh ngha. Di y l mt v d n gin:

#!/bin/sh
NAME="Zara Ali"
unset NAME
echo $NAME
Lnh trn s khng in bt c th g. Bn khng th s dng lnh unset xa cc bin m c

nh du read-only.
Cc kiu bin trong Unix/Linux

Khi mt Shell ang chy, c 3 kiu bin tn ti:
Cc bin ni b (Local Variables): Mt bin ni b l mt bin m tn ti trong trong qu

trnh thc thi ca shell. N khng c sn trong cc chng trnh m c bt u bi
Shell. Chng c thit lp ti dng nhc lnh.
Cc bin mi trng (Environment Variables): Mt bin mi trng l mt bin c sn

trong bt k tin trnh con no ca shell. Mt vi chng trnh cn cc bin mi trng
thc thi cc hm mt cch chnh xc. Thng thng mt Shell script ch nh ngha cc
bin mi trng m n cn bi cc chng trnh khi n chy.
Cc bin shell (Shell Variables): Mt bin shell l mt bin c bit m c thit lp bi

Shell v c yu cu bi Shell thc thi cc hm mt cch chnh xc. Mt s bin ny
l bin mi trng, trong khi s khc l bin ni b.
Cc bin c bit trong Unix

Chng hng dn trc cnh bo v s dng cc k t c bit trong tn bin ca bn. iu
ny bi v nhng k t ny c s dng trong tn cc bin c bit trong Unix. Nhng bin ny
c gi cho cc chc nng c bit.
V d, k t $ i din cho s Process ID, hoc PID ca shell hin ti.
$echo $$
Page 71
Lnh trn s vit Process ID ca shell hin ti:

29949
Di y l bng lit k cc bin c bit m bn c th s dng trong Shell script:
Bin
Miu t
$0
Tn file ca script hin ti.

Nhng bin ny tng ng vi cc tham s m mt script c gi. Ti y n l s
$n
thp phn nguyn dng tng ng vi v tr ca mt tham s (tham s u tin l

$1, tham s th hai l $2).
$#
$*
$@
$?
$$
$!
S cc tham s cung cp cho mt script.

Tt c cc tham s c trch dn kp. Nu mt script nhn hai tham s, $* l tng
ng vi $1 $2.
Tt c cc tham s c trch dn kp ring r. Nu mt script nhn 2 tham s, $@
l tng ng vi $1 $2.
Trng thi thot ra ca lnh trc c chy.
S tin trnh ca shell hin ti. i vi Shell script, y l s Process ID m chng
ang chy.
S tin trnh ca lnh background trc.
Cc tham s dng lnh (command-line) trong

Unix/Linux
Cc bin dng lnh $1, $2, $3, , $9 l cc tham s v tr, vi $0 ch ti lnh, chng trnh, Shell
script hoc chc nng thc s v $1, $2, $3, , $9 l cc tham s ca lnh .
Script di y s dng cc bin c bit lin quan ti dng lnh:
Page 72
#!/bin/sh
echo "File Name: $0"

echo "First Parameter : $1"
echo "Second Parameter : $2"
echo "Quoted Values: $@"
echo "Quoted Values: $*"
echo "Total Number of Parameters : $#"
Ti y l mt ln chy mu cho script trn:

$./test.sh Zara Ali
File Name : ./test.sh
First Parameter : Zara
Second Parameter : Ali
Quoted Values: Zara Ali
Total Number of Parameters : 2
Cc tham s c bit $* v $@ trong Unix/Linux

C nhng tham s c bit m cho php truy cp v tt c cc tham s ca cc dng lnh cng
mt lc. C $* v $@ s hot ng tng t tr khi chng c bao quanh bi trch dn ().
C hai tham s xc nh tt c cc tham s ca dng lnh, nhng $* nhn ton b danh sch lm
tham s vi cc khong cch trng gia v $@ nhn ton b danh sch lm tham s v phn
bit chng thnh cc tham s ring r.
Chng ta c th vit Shell script nh di x l mt s khng bit cc tham s dng lnh vi
hoc tham s c bit $* hoc $@.
#!/bin/sh
for TOKEN in $*
do
echo $TOKEN
Page 73
done
Chng ta chy mu cho script trn:

$./test.sh Zara Ali 10 Years Old
Zara
Ali
10
Years
Old
Ghi ch: Ti y do...done l mt dng ca loop m chng ta s bn lun trong chng hng
dn sau.
Trng thi thot (Exit) trong Unix/Linux

Bin $? i din cho trng thi thot ca lnh trc.
Trng thi thot l mt gi tr s tr v bi mi lnh khi n hon tt. Theo quy nh, hu ht cc
lnh tr v mt trng thi thot l 0 nu chng thc hin thnh cng v 1 nu chng khng thnh
cng.
Mt vi lnh tr v cc trng thi thot vi phn thm vo khc v cc l do ring. V d, mt s
lnh phn bit gia cc loi li v s tr v cc gi tr thot a dng ph thuc vo kiu ca li.
Di y l cc v d v lnh thc hin thnh cng:
$./test.sh Zara Ali
File Name : ./test.sh
First Parameter : Zara
Second Parameter : Ali
Total Number of Parameters : 2
$echo $?
0
$
Page 74
S dng mng trong Shell

Mt bin shell l c kh nng gi mt gi tr n. Kiu ny ca cc bin c gi l cc bin
scalar.
Shell h tr cc kiu khc nhau ca bin c gi l mt bin mng m c th gi nhiu gi tr ti
cng mt thi im. Mng cung cp mt phng thc to nhm mt tp hp cc bin. Thay v to
mt tn mi cho mi bin c yu cu, bn c th s dng mt bin mng lu tt c cc bin
khc.
Tt c cc quy tc v tn c bn lun trong chng Cc bin shell s c p dng trong khi
t tn mng.
nh ngha cc gi tr mng trong Unix/Linux

im khc nhau gia mt bin mng v mt bin scalar c th c gii thch nh sau:
Khi bn ang c gng biu din tn ca cc sinh vin khc nhau nh mt tp hp ca bin. Mi
bin n l mt bin scalar nh sau:
NAME01="Zara"
NAME02="Qadir"
NAME03="Mahnaz"
NAME04="Ayan"
NAME05="Daisy"
Chng ta s dng mt mng n gi tt c cc tn c cp trn. Sau y l mt

phng thc n gin cho vic to mt bin mng gn mt gi tr cho mt trong s chng. iu
ny c din t nh sau:
array_name[index]=value
Ti y array_name l tn ca mng, index l ch mc ca cc item trong mng m bn mun thit

lp v value l gi tr m bn mun thit lp cho mc .
Di y l v d, cc lnh sau:
NAME[0]="Zara"
NAME[1]="Qadir"
Page 75
NAME[2]="Mahnaz"
NAME[3]="Ayan"
NAME[4]="Daisy"
Nu bn ang s dng ksh shell th ti y c php ca mng l:

set -A array_name value1 value2 ... valuen
Nu bn ang s dng bash shell th ti y c php ca mng l:

array_name=(value1 ... valuen)
Truy cp vo cc gi tr mng trong Unix/Linux

Sau khi bn thit lp bt k gi tr mng no, bn c th truy cp vo n nh sau:
Ti y array_name l tn mng, v index l ch mc ca cc gi tr c truy cp. Di y l v

d n gin:
#!/bin/sh
NAME[0]="Zara"
NAME[1]="Qadir"
NAME[2]="Mahnaz"
NAME[3]="Ayan"
NAME[4]="Daisy"
echo "First Index: "
echo "Second Index: "
$./test.sh
First Index: Zara
Second Index: Qadir
Bn c th truy cp vo tt c cc item trong mt mng theo mt trong cc cch sau:
Page 76
$ {array_name[*]}
$ {array_name[@]}
Ti y array_name l tn mng bn ang quan tm n. Di y l v d n gin:

#!/bin/sh
NAME[0]="Zara"
NAME[1]="Qadir"
NAME[2]="Mahnaz"
NAME[3]="Ayan"
NAME[4]="Daisy"
echo "First Method:$ {NAME[*]}"
echo "Second Method:$ {NAME[@]}"
$./test.sh
First Method: Zara Qadir Mahnaz Ayan Daisy
Second Method: Zara Qadir Mahnaz Ayan Daisy
Unix - Cc ton t Shell c bn

rt nhiu ton t c h tr bi mi Shell. Phn hng dn ca chng ti da trn c s Shell
mc nh (Bourne) v th chng ta ang bn v cc ton t ca Bourne shell trong chng ny.
C cc ton t sau m chng ta cn quan tm:
Cc ton t s hc
Cc ton t quan h
Cc ton t logic
Cc ton t chui
Cc ton t kim tra file
Page 77
Bourne shell lc u khng c bt c mt k thut no trnh by s hc n gin, nhng n s

dng chng trnh ngoi vi, hoc l awk hoc l chng trnh n gin hn expr.
Di y l v d n gin cng hai s:
#!/bin/sh
val=èxpr 2 + 2`
echo "Total value : $val"
Total value : 4
Nhng im m bn cn lu l:
Phi c mt khong trng gia hai ton t v 2 s din t, v d 2+2 l khng ng, n
nn c vit l 2 + 2.
S din t y nn c bao quanh bi ``, gi l du phy b nghch o.
Cc ton t s hc trong Unix/Linux

Cc ton t s hc sau c h tr bi Bourne shell.
Gi s bin a gi gi tr 10 v bin b gi gi tr 20, th khi :
V d:
Ton
t
Miu t
V d
èxpr
$a +
+
Php cng thm gi tr mi bn vo ton t
$b`
kt
qu
l 30
Page 78
èxpr
$a -
Php tr tr gi tr bn phi ca ton t bn tri
$b`
kt
qu
l -10
èxpr
$a \*
$b`
*
Php nhn nhn gi tr trn mi bn vi ton t.
kt
qu
l
200
èxpr
$b /
/
Php chia chia gi tr bn phi cho gi tr bn tri
$a`
kt
qu
l 2
èxpr
$b %
%
Ly s d ly phn cn li sau khi chia gi tr tri cho gi tr bn phi
$a`
kt
qu
l 0
a=$b
s
=
Php gn gn ton hng tri cho ton hng phi
gn
gi tr
ca b
cho a
Page 79
[ $a
== $b
==
Php bng so snh hai s, nu c hai u ging nhau th kt qu tr v l

true.
] s
tr v
kt
qu
False.
[ $a
!= $b
!=
Php khng cn bng so snh hai s, nu c hai s khc nhau th gi tr tr

v l true.
] s
tr v
kt
qu
True.
N l rt quan trng ghi nh rng ti y tt c cc s din t c iu kin s c t trong

hai du ngoc m vung ([]) vi mt du cch trng quanh chng, v d [$a == $b ] l ng, v
[$a==$b] l khng ng.
Tt c cc ton t s hc c thc hin s dng cc s nguyn di.
Cc ton t quan h trong Unix/Linux

Bourne shell h tr cc ton t quan h sau m l ring vi cc gi tr s. Nhng ton t ny
khng lm vic cho chui tr khi gi tr ca n l s.
V d, cc ton t sau s kim tra mt quan h gia 10 v 20, cng l gia 10 v 20 nhng
khng gia ten v twenty.
Gi s bin a gi gi tr 10 v bin b gi gi tr 20 th khi :
V d
Ton
t
-eq
Miu t
V d
Kim tra gi tr ca hai ton hng l cn bng hoc khng, nu c th iu kin
[ $a -
Page 80
tr ln ng.
eq $b
] l
khng
ng.
[ $a -ne
Kim tra gi tr ca hai ton hng l cn bng hoc khng, nu khng cn
ne $b
bng th iu kin tr ln ng.
] l
ng.
[ $a -gt
Kim tra nu gi tr ca ton hng tri ln hn gi tr ca ton hng phi, nu

ng th iu kin tr nn ng.
gt $b
] l
khng
ng.
[ $a -lt
Kim tra nu gi tr ca ton hng tri nh hn gi tr ca ton hng phi, nu
lt $b ]
ng th iu kin tr nn ng.
l
ng.
[ $a -ge
Kim tra nu gi tr ca ton hng tri ln hn hoc bng gi tr ca ton hng

phi, nu ng th iu kin tr nn ng.
ge $b
] l
khng
ng.
[ $a -le
Kim tra nu gi tr ca ton hng tri nh hn hoc bng gi tr ca ton hng le $b ]

phi, nu ng th iu kin tr nn ng.
l
ng.
N l rt quan trng ghi nh rng ti y tt c cc s din t c iu kin s c t trong

du ngoc m vung ([]) vi du cch trng quanh chng, v d [ $a <= $b ] l ng v [$a<=$b] l
khng ng.
Cc ton t logic trong Unix/Linux

Page 81
C cc ton t logic sau c h tr bi Bourne Shell

Gi s bin a gi gi tr 10 v bin b gi gi tr 20, th di y l v d s dng tt c cc ton t
logic.
V d
Ton
t
Miu t
V d
[!
!
Php ph nh. Nu iu kin ng th gi tr l sai v ngc li.
false ]
l
true.
[ $a lt 20 o $b -o
Php hoc. Nu mt trong cc ton hng l ng th iu kin l ng.
gt
100 ]
l
true.
[ $a lt 20 a $b -a
Php v. Nu c hai ton hng u ng th iu kin l ng, ngoi ra l sai.. gt

100 ]
l
false.
Cc ton t chui trong Unix/Linux

Cc ton t chui sau c h tr bi Bourne Shell.
Gi s bin a gi gi tr abc v bin b gi gi tr efg:
V d
Page 82
Ton
t
Miu t
V d
[ $a =
=
Kim tra nu gi tr ca hai ton hng l cn bng hoc khng, nu c th iu
$b ] l
kin l ng.
khng
ng.
[ $a
!=
Kim tra nu gi tr ca hai ton hng c cn bng hoc khng, nu khng cn != $b

bng th iu kin l ng.
] l
ng.
[ -z
-z
Kim tra nu c ton hng chui cho l 0. Nu n c di l 0 th n tr
$a ] l
v l ng.
khng
ng.
[ -z
-n
Kim tra nu c ton hng chui cho l khc 0. Nu di khc 0 th n tr $a ] l

v l ng.
khng
ng.
[ $a ]
str
Kim tra nu str khng l chui trng. Nu l chui trng th n tr v l sai.
l
khng
sai.
Cc ton t kim tra file trong Unix/Linux

Cc ton t sau kim tra cc s hu c bn lin kt vi mt file Unix.
Gi s mt bin file gi mt tn file ang tn ti l test vi kch c l 100 byte v c cho php
c, vit v chy.
V d
Page 83
Ton
t
Miu t
V d
[ -b
-b file
Kim tra nu file l mt file khi c bit, nu ng th iu kin l ng.
$file ]
l sai.
[ -c
-c file
Kim tra nu file l mt file k t c bit, nu ng th iu kin l ng.
$file ]
l sai.
[ -d
$file ]
-d file
Kim tra nu file l mt th mc, nu ng th iu kin l ng.
l
khng
ng.
[ -f
-f file
Kim tra nu file l file thng nh tri ngc vi th mc hoc l file c bit, $file ]
nu ng th iu kin l ng.
l
ng.
[ -g
-g file
Kim tra nu file c ID nhm thit lp (SGID), nu ng th iu kin l ng.
$file ]
l sai.
[ -k
-k file
Kim tra nu file c thit lp sticky bit, nu ng th iu kin l ng.
$file ]
l sai.
[ -p
-p file
Kim tra nu file l mt pipe c t tn, nu ng th iu kin l ng.
$file ]
l sai.
-t file
Kim tra nu k hiu nhn din file c m v lin kt vi mt terminal,
[ -t
nu ng th iu kin l ng.
$file ]
Page 84
l sai.
[ -u
-u file
Kim tra nu file c SUID, nu ng th iu kin l ng.
$file ]
l sai.
[ -r
-r file
Kim tra nu file l c c, nu ng th iu kin l ng.
$file ]
l
ng.
[ -w
-w file
Kim tra nu file l vit c, nu ng th iu kin l ng.
$file ]
l
ng.
[ -x
-x file
Kim tra nu file l chy c, nu ng th iu kin l ng.
$file ]
l
ng.
[ -s
-s file
Kim tra nu file l chy c, nu ng th iu kin l ng.
$file ]
l
ng.
[ -e
-e file
Kim tra nu file tn ti, vn ng ngay c khi file l mt th mc nhng tn
$file ]
ti.
l
ng.
Cc ton t C Shell trong Unix/Linux:

Sau y l ng link miu t ngn gn v cc ton t C Shell.
Cc ton t C Shell
Cc ton t Korn Shell trong Unix/Linux:

Page 85
Sau y l ng link miu t ngn gn v cc ton t Korn Shell.

Cc ton t Korn Shell
iu khin lung trong Shell

Trong khi vit mt Shell script, c th c mt tnh hung khi bn cn theo mt path ngoi 2 path
c cung cp. V th bn cn to cch s dng ca cc lnh c iu kin m cho php
chng trnh ca bn to cc quyt nh chnh xc v thc hin cc hnh ng ng.
Unix Shell h tr cc lnh c iu kin m c s dng thc hin cc hnh ng khc nhau
da trn cc iu kin a dng. Ti y chng ta s gii thch hai lnh iu khin lung:
Lnh if...else
Lnh case...esac
Lnh ifelse trong Unix/Linux

Lnh ny l mt lnh iu khin lung hu ch, c s dng la chn mt ty chn t mt tp
hp ty chn cho.
Unix Shell h tr cc mu lnh ifelse sau:
Lnh if...fi
Lnh if...else...fi
Lnh if...elif...else...fi
Hu ht cc lnh if kim tra mi quan h bng cch s dng cc ton t quan h c cp

trong chng trc.
Lnh case...esac trong Unix/Linux

Bn c th s dng nhiu lnh ifelif thc hin mt nhnh c nhiu la chn. Tuy nhin, y
khng l gii php tt nht, c bit khi tt c cc nhnh ph thuc vo gi tr ca mt bin n.
Unix shell h tr lnh case...esac m gii quyt chnh xc tnh hung ny, v n thc hin theo
cch hiu qu hn l lp li s dng nhiu lnh ifelif.
Page 86
Ch c mt mu ca lnh caseesac m c lit k y:
Lnh case...esac
Lnh case...esac ca Unix Shell l tng t vi lnh switch...case m chng ta c trong cc

chng trnh C hoc C++ v PERL etc.
Vng lp trong Unix

Vng lp l cng c chng trnh c tnh nng mnh, cho php bn c th lp li mt tp hp cc
lnh. Trong chng ny, bn s tm hiu qua cc v d thc hnh v vng lp c trong cc chng
trnh shell.
Vng lp while
Vng lp for
Vng lp until
Vng lp select
Bn s s dng cc vng lp khc nhau trn c s cc tnh hung khc nhau. V d, vng lp
while s chy lnh cho ti khi iu kin cho vn cn ng, trong khi vng lp until s chy
ti khi iu kin cho tr nn ng.
Mt khi bn c cc bi thc hnh chng trnh tt, bn s bt u s dng vng lp thch hp trn
c s tnh hung cho. y, vng lp while v for l c sn trong hu ht cc ngn ng
chng trnh khc nh C, C++ v PERL etc.
Lng cc vng lp trong Unix/Linux

Tt c cc vng lp h tr khi nim lng, c ngha l bn c th t mt vng lp vo bn trong
mt vng lp tng t hoc cc vng lp khc. Vic lng ny c th khng gii hn s lng ti a
vng lp, n ph thuc vo yu cu ca bn.
Di y l v d ca lng vng lp while, v theo cch tng t, cc vng lp khc c th c
lng ty theo yu cu chng trnh.
Lng vng lp while trong Unix/Linux

N l c th s dng vng lp while nh l mt phn ca thn ca mt vng lp while khc.
Page 87
C php:
while command1 ; # this is loop1, the outer loop
do
Statement(s) to be executed if command1 is true
while command2 ; # this is loop2, the inner loop

do
done

done
V d:
Sau y l v d n gin ca lng vng lp:
#!/bin/sh
a=0
while [ "$a" -lt 10 ]
# this is loop1
do
b="$a"
while [ "$b" -ge 0 ]
# this is loop2
do
echo -n "$b "
b=èxpr $b - 1`
done
echo
a=èxpr $a + 1`
done
N to ra kt qu sau. N l quan trng ghi nh cch echo -n lm vic y. Ti y ty chn n cho php echo trnh vic in mt dng k t mi.
Page 88
0
1 0
2 1 0
3 2 1 0
4 3 2 1 0
5 4 3 2 1 0
6 5 4 3 2 1 0
7 6 5 4 3 2 1 0
8 7 6 5 4 3 2 1 0
9 8 7 6 5 4 3 2 1 0
iu khin vng lp trong Unix

Chng trc bn c hng dn cch to vng lp v lm vic vi chng thc hin cc
nhim v khc nhau. i khi bn cn dng mt vng lp hoc tip tc tin hnh qu trnh lp i lp
li ca chng.
Trong chng ny, bn s hc 2 lnh c s dng trong iu khin vng lp Shell:
1. Lnh break
2. Lnh continue
Vng lp v hn trong Unix/Linux

Tt c vng lp c mt vng i gii hn v chng kt thc khi iu kin l ng hoc sai ph
thuc vo vng lp.
Mt vng lp c th tip tc tin hnh vnh vin do cha kt ni ng vi iu kin yu cu. Mt
vng lp v hn l mt vng lp m chy vi s ln khng m c.
V d
Di y l v d n gin v s dng vng lp while hin th cc s t 0 n 9.
#!/bin/sh
a=10
Page 89
while [ $a -ge 10 ]
do
echo $a
a=èxpr $a + 1`
done
Vng lp ny l vng lp v hn bi v a lun lun ln hn hoc bng 10 v n s khng bao gi

nh hn 10.
Lnh break trong Unix/Linux

Lnh break c s dng kt thc tin trnh chy ca mt vng lp y , sau khi hon thnh
chy tt c cc dng trong code ti lnh break ny. N sau bc ra khi on code sau khi kt
thuc vng lp.
C php
Lnh break sau c s dng thot khi mt vng lp.
break
Lnh break c th c s dng thot khi mt vng lp s dng nh dng sau:

break n
Ti y n xc nh vng lp th n c bao quanh thot ra khi t :
V d
V d sau ch vng lp sau s kt thc ngay sau khi iu kin tr thnh 5:
#!/bin/sh
a=0
while [ $a -lt 10 ]
do
echo $a
Page 90
if [ $a -eq 5 ]
then
break
fi
a=èxpr $a + 1`
done
N s hin th kt qu sau:
0
1
2
3
4
5
Di y l mt v d n gin ca lng vng lp. Script thot ra khi c hai vng lp nu var1
bng 2 v var2 bng 0.
#!/bin/sh
for var1 in 1 2 3
do
for var2 in 0 5
do
if [ $var1 -eq 2 -a $var2 -eq 0 ]
then
break 2
else
echo "$var1 $var2"
fi
done
done
Page 91
N s to kt qu sau. Trong vng lp bn trong bn c mt lnh break vi i s 2. N ch rng

nu iu kin c tha mn bn nn thot khi vng lp bn ngoi.
1 0
1 5
Lnh continue trong Unix/Linux

Lnh continue ny tng t nh lnh break, ngoi tr vic n gy ra s lp li hin ti ca cc
vng lp thot ra, ch khng phi ton b vng lp.
Lnh ny c s dng khi mt li xy ra v bn mun c chy s lp k tip ca vng lp.
C php:
continue
Ging vi lnh break, mt i s nguyn c th c cung cp cho lnh continue nhy qua
lnh ny t vng lp c lng.
continue n
y n xc nh vng lp c bao th n tip tc t .
V d
Vng lp sau s dng lnh continue m tr li t lnh continue v bt u tin trnh lnh k tip.
#!/bin/sh
NUMS="1 2 3 4 5 6 7"
for NUM in $NUMS

do
Q=èxpr $NUM % 2`
if [ $Q -eq 0 ]
then
echo "Number is an even number!!"
continue
Page 92
fi
echo "Found odd number"
done
Found odd number
Number is an even number!!
Found odd number
Found odd number
Found odd number
Trnh thay th Shell

rnh thay th (Substitution) trong Unix/Linux l g?
Shell thc hin php th khi n gp mt biu thc m cha mt hoc nhiu k t c bit.
V d:
Di y l v d, trong khi in mt gi tr ca bin, n s c thay th bi gi tr ca bin. Cng
thi gian \n c thay th bi dng mi.
#!/bin/sh
a=10
echo -e "Value of a is $a \n"
N s to kt qu nh di y. Ti y, chc nng -e s cho php bin dch dy thot du cho

ngc.
Value of a is 10
Nu khng c chc nng -e th n to ra kt qu sau:

Value of a is 10\n
Page 93
Di y l cc dy thot m c th c s dng bi lnh echo:
Dy thot
Miu t
\\
Du cho ngc
\a
Du hiu cnh bo (BEL)
\b
Phm li (backspace)
\c
Gch cho xung dng
\f
form feed
\n
Dng mi
\r
Quay tr li
\t
Tab ngang
\v
Tab dc
Bn c th s dng chc nng -E khng cho php bin dch du ngoc cho (mc nh).
Bn c th s dng chc nng -n khng cho php chn ca dng mi.
Trnh thay th lnh (Command Substitution) trong

Unix/Linux
Trnh thay th lnh l mt k thut m bi n Shell thc hin mt tp hp cc lnh cung cp v
sau thay th v tr kt qu ca cc lnh.
C php
Trnh thay th lnh c thc hin khi mt lnh c cung cp nh sau:
`command`
Page 94
Khi thc hin trnh thay th lnh, m bo rng bn ang s dng 2 du trch dn n kiu (`), ch
khng phi l .
V d
Trnh thay th lnh thng thng c s dng gn u ra ca mt lnh ti mt bin. Mi mt
v d sau gii thch cch s dng trnh thay th lnh.
#!/bin/sh
DATE=`date`
echo "Date is $DATE"
USERS=`who | wc -l`
echo "Logged in user are $USERS"
UP=`date ; uptime`
echo "Uptime is $UP"
Date is Thu Jul
2 03:59:57 MST 2009
Logged in user are 1

Uptime is Thu Jul
2 03:59:57 MST 2009
03:59:57 up 20 days, 14:03,
1 user,
load avg: 0.13, 0.07, 0.15
Trnh thay th bin (Variable Substitution) trong

Unix/Linux
S thay th bin cho php ngi lp trnh Shell thao tc gi tr ca bin da trn trng thi ca n.
Di y l bng cho tt c cc trnh thay th c th:
Mu
Miu t
$ {var}
Thay th gi tr ca var.
Page 95
$ {var:-word}
$ {var:=word}
$ {var:?message}
$ {var:+word}
Nu var l null hoc unset, th word c thay th cho var. Gi tr

ca var khng thay i.
Nu var l null hoc unset, var c thit lp l gi tr caword .
Nu var l null hoc unset, message c in l li. Lnh ny kim tra
xem cc bin c c thit lp ng khng.
Nu var c thit lp, word c thay th cho var. Gi tr
cavar khng thay i.
V d:
Di y l v d minh ha cc trng thi a dng ca trnh thay th trn:
#!/bin/sh
echo $ {var:-"Variable is not set"}

echo "1 - Value of var is $ {var}"
echo $ {var:="Variable is not set"}

unset var
echo $ {var:+"This is default value"}
echo "3 - Value of var is $ var"
var="Prefix"
echo $ {var:+"This is default value"}
echo "4 - Value of var is $ var"
echo $ {var:?"Print this message"}

Page 96
Variable is not set

1 - Value of var is
Variable is not set
2 - Value of var is Variable is not set
3 - Value of var is
This is default value
4 - Value of var is Prefix
Prefix
5 - Value of var is Prefix
Unix - Cc k thut trch dn

Cc siu k t trong Unix/Linux
Shell cung cp cc siu k t a dng m c ngha c bit trong khi s dng chng trong bt k
Shell script no v gy ra s gii hn ca mt t tr khi c trch dn.
V d: siu k t ? kt ni vi mt k t n trong khi lit k cc file trong mt th mc v siu k
t * s kt ni nhiu hn mt k t. Di y lit k mt danh sch ca hu ht cc k t c bit
trong shell (cng c gi l siu k t).
* ? [ ] ' " \ $ ; & ( ) | ^ < > new-line space tab
Mt k t c th c trch dn bng cch t trc n vi mt du \.
Di y l v d ch cch in mt * hoc mt ?:
#!/bin/sh
echo Hello; Word
Hello
./test.sh: line 2: Word: command not found
Page 97
shell returned 127
By gi chng ta s dng mt k t c trch dn:

#!/bin/sh
echo Hello\; Word
N s to ra kt qu:
Hello; Word
K hiu $ l mt siu k t, v th n phi c trch dn trnh shell thc hin cc cng vic
c bit lin quan n n:
#!/bin/sh
echo "I have \$1200"
Code trn to ra kt qu sau:

I have $1200
C 4 kiu mu trch dn c chng ti lit k trong bng sau:
Trch dn
Trch dn n
Miu t
Tt c cc k t gia trch dn ny khng cn ngha c bit na vi
shell.
Hu ht cc k t gia trch dn ny khng cn ngha c bit, tr cc
k t sau:
Trch dn kp
\$
\'
Page 98
\"
\\
Du gch cho
Bt k k t no ng sau du cho ngc \ khng cn ngha c bit
ngc
ca n.
Trch dn ngc
Bt k k t no gia trch dn ngc c shell i x nh l mt
(``)
lnh v c chy.
Cc trch dn n trong Unix/Linux:

Chng ta xem xt mt lnh echo m cha nhiu k t c bit trong shell sau:
echo <-$1500.**>; (update?) [y|n]
t mt du cho ngc (\) trc mi k t c bit l mt vic gy chn ngt v lm cho code
kh c.
echo \<-\$1500.\*\*\>\; $update\?$ \[y\|n\]
C mt cch d dng trch dn mt nhm ln cc k t. Chng ta t mt trch dn n (`)ti

phn u v cui ca chui:
echo '<-$1500.**>; (update?) [y|n]'
Bt k k t no trong trch dn n c trch dn tng t nh c mt du cho ngc trc

mi k t. V th, by gi mi lnh echo ny hin th mt cch chnh xc.
Nu mt trch dn n xut hin trong mt chui to kt qu u ra, bn khng nn t ton b
chui trong trch dn n, thay vo bn nn t trc chng mt du \ nh sau:
echo 'It\'s Shell Programming'
Trch dn kp trong Unix/Linux

Bn ang c gng chy Shell script sau. Script ny s dng trch dn n:
VAR=ZARA
echo '$VAR owes <-$1500.**>; [ as of (`date +%m/%d`) ]'
Page 99
$VAR owes <-$1500.**>; [ as of (`date +%m/%d`) ]
Nhng n khng phi th m bn mun hin th. Nh vy r rng l trch dn n ngn cn trnh
thay th bin. Nu bn mun thay th gi tr ca bin v thc hin cng vic sau du phy nh bn
mong i th khi bn cn t cc lnh ca bn trong trch dn kp nh sau:
VAR=ZARA
echo "$VAR owes <-\$1500.**>; [ as of (`date +%m/%d`) ]"
ZARA owes <-$1500.**>; [ as of (07/02) ]
Trch dn kp loi b ngha c bit ca tt c k t c bit tr cc trng hp sau:
$ cho trnh thay th tham s
Trch dn ngc cho trnh thay th lnh
\$ th hin bng ch ca k hiu la
\` th hin bng ch ca k hiu trch dn ngc
\" cho php trch dn kp c nhng
\\ cho php k t du gch cho ngc c nhng
Tt c cc dng \k t khc c biu hin bng ngha ch ca n (khng phi c bit)
Bt k k t no trong trch dn n c trch dn nh l mt du cho ngc phn trc mi

k t. V th by gi lnh echo ny hin th chnh xc.
Nu mt trch dn n xut hin trong mt chui kt qu u ra, bn khng nn t ton b
chui trong trch dn n m thay vo bn nn t trc n mt du cho ngc nh sau:
echo 'It\'s Shell Programming'
Trch dn ngc trong Unix/Linux

t bt k lnh shell vo gia cc trch dn ngc th shell s thi hnh lnh .
Page 100
C php
y l c php n gin t bt k lnh Shell no vo gia trch dn ngc:
V d:
var=`command`
V d:
Sau y chng ti s chy lnh date v gi kt qu trong bin DATA:
DATE=`date`
echo "Current Date: $DATE"
N to ra kt qu l:
Current Date: Thu Jul
2 05:28:45 MST 2009
iu hng IO trong Unix/Linux

Hu ht cc lnh h thng Unix nhn d liu input t terminal ca bn v gi output li cho
terminal ca bn. Mt lnh thng c input ca n t mt a im gi l input tiu chun
(standard input), m xy ra vi terminal ca bn theo mc nh. Theo cch tng t, mt lnh
thng vit output ti u ra tiu chun (standard output), m cng xy ra vi terminal ca bn
theo mc nh.
iu hng li output trong Unix/Linux

output t mt lnh thng c khuynh hng ch cho standard output c th d dng nh hng
ti mt file. Kh nng ny c bit n nh l s iu hng li u ra.
Nu cc k hiu > file c gn ti bt k lnh no th n thng vit u ra ca n ti standard
output, u ra ca lnh s c ghi vo file thay v terminal ca bn.
Chng ta cng kim tra lnh who m s iu hng li ton b u ra ca lnh trong tp users:
$ who > users
Page 101
Ch rng, khng u ra no xut hin trn terminal. l bi v u ra c iu hng li

t thit b u ra tiu chun mc nh (terminal) vo trong mt file c th. Nu bn kim tra tp
users th khi file s c ni dung y :
$ cat users
oko
tty01
Sep 12 07:30
ai
tty15
Sep 12 13:32
ruth
tty21
Sep 12 10:10
pat
tty24
Sep 12 13:07
steve
tty25
Sep 12 13:03
Nu mt lnh c u ra c iu hng li ti mt file v file cha mt vi d liu, th d

liu s b tht lc. Xem xt v d sau:
$ echo line 1 > users
$ cat users
line 1
$
Bn c th s dng ton t >> gn u ra vo mt file ang tn ti nh sau:

$ echo line 2 >> users
$ cat users
line 1
line 2
$
S iu hng li input trong Unix/Linux

Tng t nh u ra ca lnh, input ca lnh cng c th iu hng li t mt file. Khi k t ln
hn > c s dng cho iu hng input, th k t nh hn < c s dng iu hng li
input ca lnh.
Cc lnh m thng nhn input ca n t input tiu chun c th c input t mt file theo thao tc
ca ngi s dng. V d, tnh ton s lng dng trong mt tp users trn, bn c th chy
lnh nh sau:
Page 102
$ wc -l users
2 users
$
y n s to ra kt qu l 2 dng. Bn c th tnh ton s dng trong file bi iu hng li

input tiu chun ca lnh wc t tp users.
$ wc -l < users
2
$
Ghi nh rng, c mt s khc nhau trong output bi 2 mu ca lnh wc. Trong trng hp u
tin, tn ca tp users c lit k vi s dng, cn trong trng hp th hai th khng.
Trong trng hp u, wc bit rng n ang c input ca n t tp users. Trong trng hp th
hai, n ch bit rng n ang input ca n t input tiu chun v th n khng hin th tn file.
Here document trong Unix/Linux

Mt here document c s dng iu hng li input vo trong mt shell script hoc chng
trnh tng tc.
Chng ta c th chy mt chng trnh tng tc trong mt shell script m khng cn thao tc ca
ngi s dng cung cp input yu cu cho chng trnh hoc shell script tng tc.
Mu chung cho mt here document l:
command << delimiter
document
delimiter
y, shell phin dch ton t << nh l mt ch lnh c input ti khi n tm thy mt dng
cha gii hn xc nh. Tt c input m trn dng cha gii hn sau c cho tr thnh
input tiu chun ca lnh.
Gii hn ny ni cho shell rng here document thc hin xong. Khng c n, shell tip tc c
input mi mi. Gii hn phi l mt t n m khng cha cc du cch hoc tab.
Di y l input ca lnh wc -l tnh ton tng s dng.
Page 103
$wc -l << EOF

This is a simple lookup program
for good (and bad) restaurants
in Cape Town.
EOF
3
$
Bn c th s dng here document in nhiu dng m s dng script ca bn nh sau:

#!/bin/sh
cat << EOF

in Cape Town.
EOF
Code ny s to ra kt qu sau:
in Cape Town.
Script sau chy mt khu vc vi B son vn bn vi v lu gi input vo trong tp test.txt.

#!/bin/sh
filename=test.txt
vi $filename <<EndOfCommands
i
This file was created automatically from
a shell script
^[
ZZ
EndOfCommands
Page 104
Nu bn chy script ny vi vim m hot ng tng t vi, th sau bn s thy output ging nh
sau:
$ sh test.sh
Vim: Warning: Input is not from a terminal
$
Sau khi chy script, bn s thy u ra sau c thm vo file test.txt.

$ cat test.txt
This file was created automatically from
a shell script
$
Loi b output trong Unix/Linux

i khi bn s cn chy mt lnh, nhng bn khng mun output hin th trn mn hnh. Trong
nhng trng hp nh vy, bn c th loi b u ra bng iu hng li n vo trong tp
/dev/null:
$ command > /dev/null
y, command l tn ca lnh bn mun chy. Tp /dev/null l mt file c bit m t ng loi

b tt c input ca n.
loi b c u ra ca mt lnh v u ra b li ca lnh, bn s dng s iu hng li tiu
chun iu hng li STDERR ti STDOUT.
$ command > /dev/null 2>&1
y 2 i din cho STDERR v 1 i din cho STDOUT. Bn c th hin th mt thng bo trn

STDERR bng iu hng li STDIN thnh STDERR nh sau:
$ echo message 1>&2
Cc lnh iu hng li trong Unix/Linux

Di y l danh sch y cc lnh m bn c th s dng cho iu hng li:
Page 105
Lnh
Miu t
pgm > file
u ra ca pgm c iu hng ti file.
pgm < file
Chng trnh pgm c input t file.
pgm >> file
u ra ca pgm c gn ti file.
n > file
u ra t stream vi du hiu n c iu hng ti file.
n >> file
u ra t stream vi du hiu n c gn ti file.
n >& m
Sp nhp u ra t stream n vi stream m.
n <& m
Sp nhp input t stream n vi stream m.
<< tag
input tiu chun xut pht t y qua th tip theo ti phn u ca dng.
Nhn u ra t mt chng trnh hoc mt tin trnh v gi n cho

chng trnh khc..
Ghi ch rng du hiu file 0 thng l input tiu chun (STDIN), 1 thng l u ra tiu chun
(STDOUT), v 2 thng l u ra li tiu chun (STAERR).
Cc hm Shell
Cc hm cho php bn tinh gin mt tnh nng tng th ca mt script vo mt phn nh v logic
hn m c th thc hin cng mt chc nng bt c khi no n c cn thng qua vic gi hm.
S dng cc hm thc hin cc cng vic mang tnh lp l mt cch thng minh to tnh s
dng li c ca code. Tnh s dng li ca code l mt phn quan trng ca cc quy tc
chng trnh hng i tng hin i.
Cc hm Shell l tng t nh cc chng trnh con, phng thc v cc hm ca cc chng
trnh khc.
Page 106
To cc hm trong Unix/Linux
cng b mt hm, n gin bn s dng c php sau:
function_name () {
list of commands
}
Tn hm ca bn l function_name, v n l nhng g m bn s s dng gi n t bt c

u trong script ca bn. Tn hm phi c theo sau bi du ngoc n, m c theo sau bi
mt danh sch cc lnh bao quanh trong du ngoc m ({}).
V d:
Sau y l v d n gin ca vic s dng hm:
#!/bin/sh
# Define your function here

Hello () {
echo "Hello World"
}
# Invoke your function

Hello
Khi bn chy script trn, n s to ra kt qu sau:

$./test.sh
Hello World
$
Truyn cc tham s cho mt hm trong Unix/Linux

Bn c th nh ngha mt hm m s nhn cc tham s trong khi gi cc hm . Nhng tham s
ny s c th c i din bi $1, $2 v .
Di y l v d m chng ta truyn hai tham s Zara v Ali v sau chng ta bt v in cc
tham s ny trong hm.
Page 107
#!/bin/sh

Hello () {
echo "Hello World $1 $2"
}

Hello Zara Ali
Code ny s to ra kt qu sau:
$./test.sh
Hello World Zara Ali
$
Tr li cc gi tr t mt hm trong Unix/Linux
Nu bn chy mt lnh exit t bn trong mt hm, hiu qu ca n l khng ch kt thc s vn
hnh ca hm m cn ca chng trnh Shell.
Nu bn thay cho mun kt thc s vn hnh ca hm, th c cch thot khi mt hm nh
ngha.
Da trn tnh hung bn c th tr li bt c gi tr no t hm ca bn bng cch s dng
lnh return m c c php nh sau:
return code
y code c th l bt c ci g m bn chn, nhng r rng l bn nn chn mt ci g m

c ngha hoc hu ch trong bi cnh tng th script ca bn.
V d:
Hm di y tr li gi tr 1.
#!/bin/sh
Page 108
Hello () {
echo "Hello World $1 $2"
return 10
}

Hello Zara Ali
# Capture value returnd by last command

ret=$?
echo "Return value is $ret"
Code trn to ra kt qu sau:

$./test.sh
Hello World Zara Ali
Return value is 10
$
Cc hm c lng vo nhau trong Unix/Linux

Mt trong nhng c im ng quan tm ca cc hm l chng c th l chng c th gi chnh
hm hoc gi cc hm khc. Mt hm c th gi chnh n c bit n nh hm quy.
Di y l v d gii thch s lng vo nhau ca hai hm.
#!/bin/sh
# Calling one function from another

number_one () {
echo "This is the first function speaking..."
number_two
}
number_two () {
Page 109
echo "This is now the second function speaking..."

}
# Calling function one.

number_one
This is the first function speaking...
This is now the second function speaking...
Gi hm t dng nhc lnh trong Unix/Linux

Bn c th t nh ngha ca cc hm thng c s dng bn trong mt .profile ca bn
m chng c sn mi khi bn ng nhp v bn c th s dng chng bt c khi no ti dng
nhc lnh.
Bn cng c th chn cch to nhm cc nh ngha hm ny vo trong mt file, gi ltest.sh, v
sau chy file trn Shell hin ti bng cch g t bn phm.
$. test.sh
iu ny c th thc hin c khi cc hm trong file ny c th cho php c v n c xc

nh trong Shell hin ti nh sau:
$ number_one
This is the first function speaking...
This is now the second function speaking...
$
g b mt nh ngha hm t Shell hin ti, bn c th s dng lnh unset vi chc nng.f. N

ging vi lnh m bn s dng g b nh ngha mt bin t Shell.
$unset .f function_name
ManPage Help trong Unix

Tt c cc lnh Unix i km vi cc chc nng ty v bt buc. N l rt thng thng khi bn
qun c php y ca nhng lnh ny.
Page 110
Bi v khng ai c th nh mi lnh Unix v tt c cc chc nng i km vi n, v gip bn

iu ny, Unix ngay t khi mi ra i c mt dch v trc tuyn sn sng gip bn.
Phin bn Unix ca cc file tr gip c gi l Man Pages. Nu bn bit bt c tn lnh no
nhng m bn khng bit cch s dng ca n, th Man Pages s lun sn sng gip bn n
tng chi tit.

Di y l c php n gin nhn c chi tit v bt c lnh no trong Unix trong khi ang
lm vic vi h thng ny.
$man command
V d
By gi bn tng tng bt c lnh no m bn mun nhn c s gip . Gi s bn mun
bit v lnh pwd, th sau n gin bn ch cn s dng lnh sau:
$man pwd
Lnh trn s m mt s tr gip cho bn m s cung cp cho bn cc thng tin y v

lnh pwd. Bn th thc hnh n ti dng nhc lnh nhn c nhiu chi tit hn v lnh ny.
Bn c th nhn c thng tin chi tit v lnh man bng cch s dng lnh sau:
$man man
Chi tit v Man Page trong Unix/Linux

Man Page thng c phn thnh cc khu vc, m thng thay i bi quyn ca tc gi Man
Page. Di y lit k mt s khu vc ph bin hn.
Khu vc
Miu t
NAME
Tn ca lnh
SYNOPSIS
Cch s dng chung ca cc tham s ca lnh
Page 111
DESCRIPTION Miu t chung v lnh v nhng g n lm

Miu t tt c cc i s hoc chc nng i km ca lnh
OPTIONS
Lit k cc lnh khc m trc tip lin quan ti lnh trong Man Page hoc
SEE ALSO
ging vi tnh nng ca n.

Gii thch tt c cc vn c bit n hoc cc bug m tn ti vi lnh
BUGS
hoc u ra ca n.
Cc v d v cch s dng ph bin m cung cp cho ngi c gi v
EXAMPLES
cch m lnh c s dng.

Tc gi ca Man Page/lnh.
AUTHORS
Cui cng, chng ti mun ni rng, Man Page l mt ngun quan trng v l con ng u tin
bn chn khi tm kim thng tin v cc lnh hoc cc file trong h thng Unix.
Cc lnh shell hu ch trong Unix/Linux

By gi bn bit cch thc hnh, theo link di y l chng hng dn v Cc lnh
shell hu ch s cung cp cho bn mt danh sch cc lnh quan trng v thng c s dng
trong Unix shell.
Nu bn khng bit cch s dng bt c lnh no, bn s dng Manpage nhn c thng tin
chi tit v lnh .
y l danh sch Unix Shell - Cc lnh hu ch
Regular Expression trong Unix

Mt Regular Expression l mt chui m c th s dng din t cc dy khc nhau (cch sp
xp) ca cc k t. Regular Expression thng c s dng bi cc lnh Unix khc nhau, bao
gm ed, sed, awk, grep v min gii hn vi.
Chng ny s hng dn cc bn cch s dng Regular Expression cng vi sed.
Page 112
y sed, l vit tt ca stream editor l mt b son iu hng chui m c to c quyn

cho cc script ring. V th tt c nhng d liu u vo m bn nhp n thng qua t STDOUT v
n khng thay i file u vo.
Gi sed trong Unix/Linux

Trc khi chng ta bt u, bo m rng bn c mt bn sao ni b ca tp /etc/passwd lm
vic vi sed.
Nh cp trc , sed c th c gi bng cch gi d liu thng qua mt pipe ti n nh
sau:
$ cat /etc/passwd | sed
Usage: sed [OPTION]... {script-other-script} [input-file]...
-n, --quiet, --silent

suppress automatic printing of pattern space
-e script, --expression=script
...............................
Lnh cat ni dung ca /etc/passwd ti sed thng qua pipe trong khng gian mu ca sed.
Khng gian mu l khu vc cng vic bn trong m c sed s dng thc hin cng vic ca
n.
C php chung ca sed trong Unix/Linux

Di y l c php chung cho sed:
/pattern/action
y, pattern l mt Regular Expression, m action l mt trong cc lnh c cung cp trong

bng sau. Nu pattern b b qua, th action c thc hin cho mi dng nh chng ta nhn
trn.
K t du gch cho m bao quanh pattern c yu cu bi v chng c s dng nh l du
gii hn.
Dy
Miu t
Page 113
In dng
Xa dng
s/pattern1/pattern2/
Thay th s kin ca pattern 1 bng s kin trong pattern 2.
Xa tt c cc dng vi sed
Gi sed thm ln na, nhng ln ny ni cho sed s dng lnh chnh sa xa cc dng, biu
th bng k t n d:
$ cat /etc/passwd | sed 'd'
$
Thay v gi sed bng cch gi mt file ti n thng qua mt pipe, bn c th ch dn sed c d

liu t mt file, nh trong v d sau.
Lnh sau thc hin chnh xc cng vic tng t nh phn trn nhc n. Bn th thc hnh
n m khng s dng lnh cat.
$ sed -e 'd' /etc/passwd
$
S nh v SED trong Unix/Linux

Sed cng hiu mt s th g c gi l cc a ch. a ch hoc l v tr ring trong mt file
hoc mt dy m mt lnh chnh sa ring nn c p dng. Khi sed bt gp ci g khng
c nh v, n thc hin cc hot ng ca n trn mi dng trong file.
Lnh di y thm mt a ch c bn ti lnh sed m bn ang s dng:
$ cat /etc/passwd | sed '1d' |more
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/bin/sh
man:x:6:12:man:/var/cache/man:/bin/sh
Page 114
mail:x:8:8:mail:/var/mail:/bin/sh
news:x:9:9:news:/var/spool/news:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh
$
Bn ch rng number 1 c thm trc lnh chnh sa xa. iu ny ni cho sed thc hin
lnh chnh sa trn dng u tin ca file. Trong v d ny, sed s xa dng u tin ca
/etc/passwd v in phn cn li ca file.
Cc dy a ch ca sed trong Unix/Linux

Vy nu bn mun d b nhiu hn mt dng t mt file th nh th no? Bn c th xc nh mt
dy a ch vi sed nh sau:
$ cat /etc/passwd | sed '1, 5d' |more
$
Lnh trn s p dng trn tt c cc dng t dng 1 n dng 5. V th n xa 5 dng u tin.

Bn th thc hnh theo cc dy c cung cp di y:
Dy
Miu t
'4,10d'
Dng bt u t 4 n 10 b xa.
'10,4d'
Ch dng th 10 b xa, bi v sed khng lm vic theo hng nghch li.
'4,+5d'
'2,5!d'
N s kt ni dng 4 trong file, xa dng , tip tc xa 5 dng tip theo, v sau

dng vic xa ny v in phn cn li ca file.
N s xa mi th tr t bt u dng 2 ti dng 5.
Page 115
'1~3d'
'2~2d'
N s xa dng u tin, bc qua 3 dng tip theo, v sau xa dng th 4.

Sed tip tc p dng mu xa ny ti cui cng ca file.
N ni cho sed xa dng th 2, bc qua dng tip theo, xa dng tip, v lp li
bc trn ti khi file c c ht.
'4,10p'
Bt u t dng th 4 n dng th 10 c in.
'4,d'
y l mt c php li.
',10d'
y l mt c php li.
Ghi ch: Trong khi s dng hnh ng p, bn nn s dng chc nng -n trnh lp li vic in
dng. Bn th kim tra s khc nhau gia hai lnh sau:
$ cat /etc/passwd | sed -n '1,3p'
Kim tra lnh trn m khng s dng chc nng -n nh sau:

$ cat /etc/passwd | sed '1,3p'
Lnh thay th (substitution command) trong Unix/Linux

Lnh thay th, c biu din bi s, s thay th bt k chui no m bn xc nh vi bt c chui
khc.
thay th mt chui ny vi chui khc, bn cn c mt vi cch ni cho sed ni chui u
tin ca bn kt thc v chui thay th bt u. iu ny theo truyn thng c thc hin bi
vic ngn cch 2 chui vi du gch cho.
Lnh sau thay th s kin u tin trn mt dng ca chui root vi chui amrood.
$ cat /etc/passwd | sed 's/root/amrood/'
amrood:x:0:0:root user:/root:/bin/sh
..........................
N l quan trng ghi nh rng sed ch thay th s kin u tin trn mt dng. Nu trn chui
root din ra nhiu hn mt dng th ch dng u tin s c thay th.
Page 116
ni cho sed thc hin thay th ton b, thm k t g ti phn cui ca lnh nh sau:
$ cat /etc/passwd | sed 's/root/amrood/g'
amrood:x:0:0:amrood user:/amrood:/bin/sh
...........................
Cc c hiu thay th (Substitution Flag) trong

Unix/Linux
C mt s cch s dng Flag hu dng m c th c s dng thm vo du hiu g, v bn
c th xc nh n nhiu hn mt ln.
Flag
Miu t
Thay th tt c cc kt ni (chui thay th), khng ch vi kt ni u tin.
NUMBER
Thay th ch kt ni th NUMBER.
Nu s thay th c to ra, in khng gian mu.
w FILENAME Nu s thay th c to ra, vit kt qu ti FILENAME.

I hoc i
To s kt ni trong s phn bit gia kiu ch (ch hoa v thng).

Trong ch x l thng thng ca cc k t Regular Expression c bit ^
M hoc m
v $, c hiu ny lm cho ^ kt ni vi mt chui trng sau mt dng mi v $

kt ni vi mt chui trng trc mt dng mi.
S dng mt chui thay th trong Unix/Linux

Bn c th t tm thy rng phi thc hin mt s thay th trn mt chui m bao gm k t du
gch cho. Trong trng hp ny, bn c th xc nh mt ton t khc bng cch cung cp k t
ch nh sau ch ci s:
Page 117
$ cat /etc/passwd | sed 's:/root:/amrood:g'

amrood:x:0:0:amrood user:/amrood:/bin/sh
Trong v d trn chng ta s dng du hiu gii hn : as thay v du gch cho / bi v chng ta
ang c gng tm kim /root thay v mt root n.
i v tr vi khong trng rng trong Unix/Linux

S dng chui thay th trng xa chui root t tp /etc/passwd:
$ cat /etc/passwd | sed 's/root//g'
:x:0:0::/:/bin/sh
nh v s thay th trong Unix/Linux

Nu bn mun thay th chui sh vi chui quiet ch trn dng th 10, bn c th xc nh n nh
sau:
$ cat /etc/passwd | sed '10s/sh/quiet/g'
root:x:0:0:root user:/root:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/quiet
Theo cch tng t, thay i mt dy a ch, bn c th thc hin cng vic ging nh sau:
$ cat /etc/passwd | sed '1,5s/sh/quiet/g'
root:x:0:0:root user:/root:/bin/quiet
daemon:x:1:1:daemon:/usr/sbin:/bin/quiet
bin:x:2:2:bin:/bin:/bin/quiet
Page 118
sys:x:3:3:sys:/dev:/bin/quiet
Nh bn c th thy c t kt qu u ra, 5 dng u tin ca chui sh c thay i bng

chui quiet, nhng cc dng cn li th khng c ng chm n.
Lnh kt ni trong Unix/Linux

Bn s s dng chc nng p song song vi chc nng -n in tt c cc dng kt ni nh sau:
$ cat testing | sed -n '/root/p'
[root@ip-72-167-112-17 amrood]# vi testing
S dng Regular Expression trong Unix/Linux

Trong khi kt ni vi mu, bn c th s dng Regular Expression m cung cp nhiu tnh linh
ng hn cho bn.
Kim tra v d sau m kt ni tt c cc dng bt u vi daemon v sau xa chng:
$ cat testing | sed '/^daemon/d'
Page 119
Theo sau l v d m s xa tt c cc dng kt thc vi sh:

$ cat testing | sed '/sh$/d'
Bng di lit k 4 k t c bit m rt hu ch trong cc Regular Expression:
K t
Miu t
Kt ni vi phn bt u ca cc dng.
Kt ni vi phn cui ca cc dng.
Kt ni vi bt k k t n no.
Kt ni vi 0 hoc nhiu hn s kin ca k t trc.
[chars]
Kt ni vi bt k k t no c cho trong chars (l mt cch b tr sp xp cc

k t). Bn c th s dng k t - ch mt dy ca k t.
Cc k t kt ni trong Unix/Linux
Bn nhn vo bng di lit k mt s Expression khc m gii thch cho cch s dng ca cc
siu k t. V d, cc mu sau:
Expression
Miu t
Page 120
/a.c/
Kt ni cc dng m cha cc chui nh a+c, a-c, abc, match v a3c.
/a*c/
Kt ni vi cng cc chui ging vi chui cho nh ace, yacc, v arctic.
/[tT]he/
Kt ni vi chui The v the.
/^$/
Kt ni vi cc dng trng.
/^.*$/
Kt ni vi mt dng ton b bt k dng nh th no.
/ */
Kt ni vi mt hoc nhiu khong trng.
/^$/
Kt ni vi cc dng trng.
Di y l bng lit k mt s b b tr k t m thng c s dng:
Thit lp
Miu t
[a-z]
Kt ni vi mt ch ci n thng.
[A-Z]
Kt ni vi mt ch ci n hoa.
[a-zA-Z]
Kt ni vi mt ch ci n.
[0-9]
Kt ni vi mt s n.
[a-zA-Z0-9]
Kt ni vi mt s hoc mt ch ci n.
Cc t kha lp k t trong Unix/Linux

Mt s t kha c bit thng c sn cho cc Regular Expression, c bit cc tin ch GNU m
s dng cc Regular Expression. iu ny l rt hu dng cho cc Regular Expression Sed khi
chng n gin ha cc cng vic v nng cao kh nng c ca n.
V d, cc k t t a n z cng nh cc k t t A n Z y nhim mt lp k t l cc t kha
[[:alpha:]]
Page 121
S dng t kha lp k t ch ci, lnh ny ch in nhng dng trong tp /etc/syslog.conf m bt

u vi mt k t ch ci.
$ cat /etc/syslog.conf | sed -n '/^[[:alpha:]]/p'
authpriv.*
/var/log/secure
mail.*
-/var/log/maillog
cron.*
/var/log/cron
uucp,news.crit
/var/log/spooler
local7.*
/var/log/boot.log
Bng sau l mt danh sch y ca cc t kha lp k t trong GNU sed.
Lp k t
Miu t
[[:alnum:]]
Thuc ch ci-s [a-z A-Z 0-9]
[[:alpha:]]
Bng ch ci [a-z A-Z]
[[:blank:]]
Cc k t khong trng (spaces hoc tabs)
[[:cntrl:]]
Cc k t iu khin
[[:digit:]]
Cc s [0-9]
[[:graph:]]
Bt k k t nhn thy no (tr cc khong trng trng)
[[:lower:]]
Cc k t vit thng [a-z]
[[:print:]]
Cc k t c th in c (cc k t khng phi k t iu khin)
[[:punct:]]
Cc k t du chm cu
[[:space:]]
Khong trng trng
[[:upper:]]
Cc k t vit hoa [A-Z]
Page 122
[[:xdigit:]]
Cc k s thp lc phn [0-9 a-f A-F]
Tham chiu & trong Unix/Linux

Siu k t & trong sed biu din ni dung ca mu m c kt ni. V d, gi s bn c mt tp
gi l phone.txt cha y cc s in thoi, nh sau:
5555551212
5555551213
5555551214
6665551215
6665551216
7775551217
Bn mun to mt code khu vc (3 k s u tin) c bao quanh bi du ngoc n d dng

hn khi c. thc hin iu ny, bn c th s dng k t thay th &, ging nh:
$ sed -e 's/^[[:digit:]][[:digit:]][[:digit:]]/(&)/g' phone.txt
(555)5551212
(555)5551213
(555)5551214
(666)5551215
(666)5551216
(777)5551217
y trong phn mu bn ang kt ni 3 k s u tin, v sau s dng & bn ang i ch

cho 3 k s ny vi du ngoc n bao quanh.
S dng nhiu lnh sed trong Unix/Linux

Bn c th s dng nhiu lnh sed trong mt lnh sed n nh sau:
$ sed -e 'command1' -e 'command2' ... -e 'commandN' files
Ti y, command1 ti commandN l cc kiu lnh sed c bn lun trn. Nhng lnh ny

c p dng ti mi dng trong mt danh sch cc file c cung cp bi cc file.
S dng k thut tng t, chng ta c th vit v d s in thoi trn nh sau:
Page 123
$ sed -e 's/^[[:digit:]]\{3\}/(&)/g'
\
-e 's/)[[:digit:]]\{3\}/&-/g' phone.txt
(555)555-1212
(555)555-1213
(555)555-1214
(666)555-1215
(666)555-1216
(777)555-1217
Ghi ch: Trong v d trn, thay v lp li cc t kha lp k t [[:digit:]] 3 ln, bn i n vi \{3\},

m c ngha l kt ni Regular Expression trc 3 ln. Ti y ti s dng \ xung dng,
bn nn g b n trc khi chy lnh ny.
Tham chiu ngc trong Unix/Linux

Siu k t & l hu ch, nhng hu ch hn l kh nng nh ngha cc khu vc c th trong mt
Regular Expression bn c th tham chiu chng trong cc chui i v tr. Bng vic nh ngha
cc phn c th ca mt Regular Expression, sau bn c th xem li nhng phn ny vi mt
k t tham chiu c bit.
tham chiu ngc, u tin bn phi nh ngha mt khu vc v sau xem li khu vc .
nh ngha mt khu vc, bn chn k t du ngoc n trong du cho ngc quanh mi khu vc
bn quan tm. Khu vc u tin m bn bao quanh vi du cho ngc sau c tham chiu
bi \1, khu vc th hai bi \2, v tip tc.
Gi s phone.txt c cc s liu sau:
(555)555-1212
(555)555-1213
(555)555-1214
(666)555-1215
(666)555-1216
(777)555-1217
By gi bn th lnh sau:
$ cat phone.txt | sed 's/$.*)$$.*-$$.*$$/Area \
Page 124
code: \1 Second: \2 Third: \3/'

Area code: (555) Second: 555- Third: 1212
Ghi ch:Trong v d trn, mi Regular Expression bn trong du ngoc n s c tham chiu

ngc bi \1, \2, . Ti y, ti s dng \ xung dng, bn nn g b chng trc khi chy
lnh.
C bn v h thng File trong Unix

Mt h thng file l mt tp hp logic ca cc file trn mt vng phn hoch (partition) hoc mt
a. Mt vng phn hoch l mt ni cha thng tin v c th t hp thnh mt a cng nu
mun.
a cng ca bn c th c cc vng phn hoch a dng m thng ch cha mt h thng file,
nh mt h thng file /home.
Mt h thng file mt vng phn hoch cho php duy tr v qun l cc h thng file khc nhau mt
cch logic.
Mi th trong Unix c xem xt nh l mt file, bao gm cc thit b vt l nh DVD-ROMs, USB,
a mm, .
Cu trc th mc trong Unix/Linux

Unix s dng mt cu trc h thng file c th bc, m ging mt cu trc cy t trn xung di,
vi root (/) ti c s ca h thng file v tt c cc th mc khc tri ra t .
Mt h thng file l mt tp hp ca cc file v th mc m c cc c tnh sau:
N c mt th mc gc (/) m cha cc file v th mc khc.
Mi file v th mc c xc nh duy nht bi tn ca n, th mc m trong n c tr,

v mt s nhn din duy nht, c gi theo cch c trng l inode.
Page 125
Theo quy c, th mc gc c s inode l 2 v th mc lost+found c s inode l 3. S

inode 0 v 1 khng c s dng. Cc s inode c th c gi bi trnh xc nh trong
chc nng -i ca lnh ls.
N c c tnh khc na l t cha. Khng c s ph thuc gia mt h thng file ny vi

mt h thng file khc.
Cc th mc c cc mc ch ring v thng gi cc kiu thng tin ging nhau vic t v tr

cc file d dng. Di y l cc th mc m tn ti trn cc phin bn ln ca Unix.
Th
mc
Miu t
N l th mc chnh m ch cha cc th mc cn thit cp cao nht trong cu

trc file.
/bin
V tr ny t cc file c th chy c. Chng c sn cho mi ngi dng.
/dev
y l cc thit b iu khin.
Cc lnh th mc Supervisors, cc file nh cu hnh, cc file nh cu hnh a,
/etc
danh sch ngi dng hp l, ethernet, host, l ni gi cc thng ip nghim

trng.
/lib
Cha cc file th vin c chia s v i khi cc tp lin quan n Kernel.
/boot
Cha cc file khi ng h thng (boot).
/home
Cha th mc chnh cho cc ngi s dng v cc ti khon khc.
/mnt
S dng gn kt (mount) cc h thng file tm thi, nh cdroom v a mm .
/proc
Cha tt c cc tin trnh c nh du nh mt file bi s tin trnh hoc thng

tin khc m l ng lc ca h thng.
Page 126
/tmp
Gi cc file tm thi c s dng gia qu trnh khi ng (boot) h thng.

c s dng cho cc mc ch hn hp, hoc c th c s dng bi nhiu
/usr
ngi s dng. Bao gm cc lnh v hnh chnh, cc file c chia s, cc file th

vin, v cc ci khc.
/var
/sbin
/kernel
Mt th mc c th, cha cc file bin di nh cc file ng nhp v in v bt k

kiu khc ca file m c th cha mt s lng bin ca d liu.
Cha cc file (c th chy) nh phn, thng cho qun l h thng. V d nh cc
tin ch fdisk v ifconfig.
Cha cc tp kernel.
iu hng h thng file trong Unix/Linux

By gi bn hiu cc c s ca h thng file, bn c th bt u iu hng file bn cn. Bng
di l cc lnh bn s s dng iu hng h thng.
Lnh
Miu t
cat filename
Hin th mt tn file.
cd dirname
Di chuyn bn ti th mc c xc nh.
cp file1 file2
Sao chp mt file/th mc ti v tr c xc nh.
file filename
Nhn din kiu file (nh phn, vn bn, ).
find filename dir
Tm mt file/th mc.
head filename
Ch phn bt u ca mt file.
less filename
Trnh duyt thng qua mt file t cui hoc t u.
Page 127
ls dirname
Ch ni dung ca th mc c xc nh.
mkdir dirname
To mt th mc c nh trc.
more filename
Trnh duyt thng qua mt file t u ti cui.
mv file1 file2
Di chuyn v tr hoc t li tn ca mt file/th mc.
pwd
Ch th mc hin ti m ngi s dng hin ti ang .
rm filename
G b mt file.
rmdir dirname
G b mt th mc.
tail filename
Ch phn cui ca mt file.

To mt file trng hoc sa i cc thuc tnh ca mt file.s ang tn
touch filename
ti.
whereis filename
Ch v tr ca mt file.
which filename
Ch v tr ca mt file nu n trong PATH ca bn.
Bn c th s dng Trang tr gip (Manpage Help) kim tra c php y cho mi lnh
c cp y.
Lnh df trong Unix/Linux

Cch u tin qun l khng gian vng phn hoch l vi lnh df (vit tt ca disk free).
Lnh df -k hin th khng gian a s dng trong kilobyte, nh hin th di y:
$df -k
Filesystem
1K-blocks
Used
/dev/vzfs
10485760
7836644
2649116
/devices
Available Use% Mounted on

75% /
0% /devices
Page 128
Mt s cc th mc, nh /devices, ch 0 kilobyte c s dng. Nhng file ny l nhng h thng

file c bit, v mc d chng c tr trn a di du gch cho, bi chnh chng khng chim
dng khng gian ca a.
output ca df -k thng ging trn tt c cc h thng Unix. Di y lit k nhng th m n bao
gm:
Ct
Miu t
Filesystem
Tn h thng file.
kbytes
Tng s kilo byte c sn trn phng tin lu tr
used
Tng s kilo byte c s dng (bi file).
avail
Tng s kilo byte c sn cho s dng (cn li cha c s dng).
capacity
Phn trm ca tng s khng gian c s dng bi cc file.
Mounted on
H thng file c gn kt trn ci g.
Bn c th s dng chc nng -h (vit tt ca human readable) hin th output trong mt nh

dng ch kch c bng li ch gii theo cch d hiu nht.
Lnh du trong Unix/Linux

Lnh du (vit tt ca disk usage) cho bn kh nng xc nh cc th mc ch s s dng
khng gian trn a trn mt th mc c th.
Lnh ny hu ch nu bn mun xc nh phn khng gian c s dng cho mt th mc c th.
Lnh sau s hin th s khi m mi th mc chim dng. Mt khi n c th l 512 byte hoc 1
kilo byte ph thuc vo h thng ca bn.
$du /etc
10
/etc/cron.d
126
/etc/default
/etc/dfs
Page 129
...
$
Chc nng -h to output bn d dng hn nhn thc, l gii.

$du -h /etc
5k
/etc/cron.d
63k
/etc/default
3k
/etc/dfs
...
$
Gn kt (Mounting) h thng file trong Unix/Linux

Mt h thng file phi c gn kt c th c s dng bi h thng. quan st ci g hin
ti c gn kt (c sn s dng) trn h thng ca bn, s dng lnh sau:
$ mount
/dev/vzfs on / type reiserfs (rw,usrquota,grpquota)
proc on /proc type proc (rw,nodiratime)
devpts on /dev/pts type devpts (rw)
$
Th mc /mnt, theo quy c, l ni nhng s gn kt tm thi (nh cc a CD-ROM, cc a

mm) c t ti . Nu bn cn gn kt mt h thng file, bn c th s dng
lnh mount vi c php sau:
mount -t file_system_type device_to_mount directory_to_mount_to
V d, nu bn mun gn kt mt CD-ROM ti th mc /mnt/cdrom, bn c th nhp t bn phm

nh sau:
$ mount -t iso9660 /dev/cdrom /mnt/cdrom
iu ny gi s rng thit b CD-ROM ca bn c gi /dev/cdrom v bn mun kt ni n ti

/mnt/cdrom. Bn tham kho Man Page c thng tin c th hn hoc g mount -h t dng lnh
cho cc thng tin gip .
Page 130
Sau khi gn kt, bn c th s dng lnh cd iu hng h thng file c mi nht thng qua
im kt ni m bn va mi to ra.
B gn kt (unmounting) h thng file trong Unix/Linux

b gn kt h thng file t h thng ca bn, s dng lnh unmount bng xc nh im kt
ni hoc thit b.
V d, g b cdrom, s dng lnh sau:
$ umount /dev/cdrom
Lnh mount cho bn kh nng truy cp vo h thng file, nhng trn cc h thng Unix hin i
nht, chc nng t ng kt ni thc hin ngm tin trnh ny cho ngi s dng v khng yu
cu s can thip no.
Cc hn ngch (quotas) ngi dng v nhm trong

Unix/Linux
Cc hn ngch ngi dng v nhm cung cp cc k thut m bi n lng khng gian c s
dng bi mt ngi dng n hoc tt c ngi dng trong mt nhm c th c th c gii hn
c xc nh bi ngi qun l.
Cc hn ngch hot ng thng qua 2 s gii hn m cho php ngi dng thc hin mt s hnh
ng trong lng khng gian hoc s lng khi ca a m ngi qun l xc nh gii hn
cho trc .
Gii hn mm (Soft Limit): Nu ngi dng s dng vt qu lng gii hn, yu cu

thm phn khng gian s dng, s c cp thm mt s khi na.
Gii hn cng (Hard Limit): Khi ngi dng s dng chm ti mc gii hn, yu cu
thm cho phn khng gian s dng na, s khng c khi no c thm.
Di y l cc lnh m c s dng qun l hn ngch:
Lnh
Miu t
quota
Hin th cch s dng a v gii hn cho mt ngi s dng trong nhm.
Page 131
edquota
quotacheck
setquota
quotaon
quotaoff
repquota
y l b son hn ngch. Hn ngch ngi dng hoc nhm c th

c chnh sa bng cch s dng lnh ny.
Qut h thng file v cch s dng a, to, kim tra v sa cha cc file
hn ngch.
N cng l mt lnh trong b son hn ngch.
iu ny tuyn b ti h thng m hn ngch a nn c cho php bt
trn mt hoc nhiu h thng file.
iu ny tuyn b ti h thng m hn ngch a nn c cho php tt
trn mt hoc nhiu h thng file
In cch s dng ca a v cc hn ngch cho h thng file c xc
nh.
Bn c th s dng Trang tr gip (Manpage Help) kim tra c php y cho mi lnh
c cp trn y.
Qun l ngi dng trong Unix

C 3 kiu ti khon trn mt h thng Unix:
1. Ti khon gc (Root account): N cn c gi l superuser v s c s iu khin
tuyt i ti h thng. Mt superuser c th chy bt c lnh no m khng b hn ch.
Ngi s dng ny c th c v nh ngi qun l h thng.
2. Cc ti khon h thng: Cc ti khon h thng c cn cho cc hot ng ring trong
h thng nh ti khon mail v cc ti khon sshd. Nhng ti khon ny thng c cn
cho mt s chc nng ring trn h thng ca bn, v bt c s chnh sa no ti chng
c th nh hng bt li ti h thng.
3. Cc ti khon ngi dng c nhn: Cc ti khon ny cung cp s truy cp mang tnh
tng tc ti h thng vi ngi dng v nhm s dng v thng b gii hn truy cp vo
nhng file v th mc c tnh cht quan trng.
Page 132
Unix h tr mt khi nim l ti khon nhm Group Account m to nhm mt s ti khon mt

cch logic. Mi ti khon s l mt phn ca bt c ti khon nhm no. Nhm trong Unix ng vai
tr quan trng trong vic thc hin s qun l v tin trnh v cho php ti file.
Qun l ngi v nhm s dng trong Unix/Linux

C 4 file chnh qun l ngi s dng:
1. /etc/passwd: Gi ti khon ngi dng v thng tin mt khu. File ny gi cc thng tin
quan trng v cc ti khon trn h thng Unix.
2. /etc/shadow: Gi mt khu c bin thnh mt m ca ti khon tng ng. Khng phi
tt c cc h thng u h tr file ny.
3. /etc/group: File ny gi thng tin nhm cho mi ti khon.
4. /etc/gshadow: File ny gi cc thng tin ti khon nhm bo mt.
Bn c th kim tra tt c cc file trn vi lnh cat.
Di y l cc lnh c trong phn ln cc h thng Unix to v qun l cc ti khon c nhn
v nhm.
Lnh
Miu t
useradd
Thm cc ti khon c nhn ti h thng.
usermod
Chnh sa cc thuc tnh ca ti khon c nhn.
userdel
Xa cc ti khon c nhn t h thng.
groupadd
Thm cc ti khon nhm ti h thng.
groupmod
Chnh sa cc thuc tnh ca ti khon nhm.
groupdel
D b cc ti khon nhm khi h thng.
Page 133
Bn c th s dng cc lnh trong Trang tr gip (Manpage Help) kim tra c php y
cho mi lnh c cp trn.
To mt nhm trong Unix/Linux

Bn c th s cn to cc nhm trc khi to bt k mt ti khon no, nu khng th bn phi s
dng cc nhm ang tn ti trn h thng ca bn. Bn s c tt c cc nhm c lit k trong
tp /etc/groups.
Tt c cc nhm mc nh s l cc nhm ti khon c th trn h thng v n khng c
ngh s dng chng cho cc ti khon thng thng. V th, di y l c php to mt
nhm ti khon mi.
groupadd [-g gid [-o]] [-r] [-f] groupname
Bng di lit k chi tit cc tham s:
Ty chn
Miu t
-g GID
Gi tr s ca ID nhm.
-o
Ty chn ny cho php thm nhm vi GID khng duy nht.
-r
Du hiu ny ch th s thm nhm ti ti khon h thng.

Ty chn ny khin cho n ch thot ra vi trng thi thnh cng nu nhm
-f
xc nh tn ti. Vi g, nu GID tn ti, th GID khc (duy nht)

c chn.
groupname
Tn nhm thc s c to.
Nu bn khng xc nh bt c tham s no th h thng s s dng cc gi tr mc nh.

V d sau s to mt nhm developers vi cc gi tr mc nh, m c chp thun bi hu ht
cc nh qun l.
$ groupadd developers
Page 134
Chnh sa mt nhm trong Unix/Linux

chnh sa mt nhm, s dng c php lnh groupmod:
$ groupmod -n new_modified_group_name old_group_name
thay i tn nhm developers_2 thnh deverloper, bn g nh sau:

$ groupmod -n developer developer_2
Di y l cch thay i GID thnh 545:

$ groupmod -g 545 developer
Xa mt nhm trong Unix/Linux

xa mt nhm ang tn ti, tt c th bn cn lm l lnh groupdel v tn nhm . xa
nhm developer, lnh l:
$ groupdel developer
Lnh ny ch g b nhm, khng phi bt k file no lin quan ti nhm. Cc file l vn c th truy
cp c bi ngi s hu ca n.
To mt ti khon c nhn trong Unix/Linux

Hy cng chng ti xem cch to mt ti khon c nhn mi trn h thng Unix ca bn. Di y
l c php to mt ti khon c nhn:
useradd -d homedir -g groupname -m -s shell -u userid accountname
Bng di lit k chi tit cc tham s:
Ty chn
Miu t
-d homedir
Xc nh th mc chnh cho ti khon.
-g groupname
Xc nh mt ti khon nhm cho ti khon c nhn ny.
-m
To th mc chnh nu n khng tn ti.
Page 135
-s shell
Xc nh shell mc nh cho ti khon c nhn ny.
-u userid
Bn c th xc nh ID c nhn cho ti khon ny.
accountname
Tn ti khon c nhn thc s c to ra.
Nu bn khng xc nh bt k tham s no th h thng s s dng cc gi tr mc nh. Lnh

useradd chnh sa cc tp /etc/passwd, /etc/shadow, /etc/group v to mt th mc chnh.
Di y l v d m s to mt ti khon mcmohd thit lp th mc chnh ca n ti
/home/mcmohd v nhm l developers. Ngi s dng ny l Kenny Chnh m c ch nh cho
n.
$ useradd -d /home/mcmohd -g developers -s /bin/ksh mcmohd
Trc khi thng bo lnh trn, bo m rng bn c nhm developers c to bng

lnh groupadd.
Khi mt ti khon c nhn c to, bn c th thit lp mt khu cho n bng cch s dng
lnh passwd nh sau:
$ passwd mcmohd20
Changing password for user mcmohd20.
New UNIX password:
Retype new UNIX password:
passwd: all authentication tokens updated successfully.
Khi bn g passwd accountname, n cung cp cho bn ty chn thay i mt khu c cung

cp nu bn l superuser, nu khng th bn ch c th thay i mt khu s dng lnh tng t
nhng khng xc nh tn ti khon ca bn.
Chnh sa mt ti khon
Lnh usermod cho bn kh nng to cc thay i ti mt ti khon c nhn ang tn ti t
dng lnh. N s dng cc i s nh lnh useradd, cng vi i s -l, m cho php bn thay i
tn ti khon.
Page 136
V d, thay i tn ti khon c nhn mcmohd thnh mcmohd20 v thay i th mc chnh, bn

s cn thng bo lnh sau:
$ usermod -d /home/mcmohd20 -m -l mcmohd mcmohd20
Xa mt ti khon trong Unix/Linux

Lnh userdel c th c s dng xa mt ti khon c nhn ang tn ti. Lnh ny l rt
nguy him nu khng c s dng vi s cn trng.
Ch c mt i s hoc mt ty chn c sn cho lnh: .r, g b th mc chnh v mail ca ti
khon.
V d, g b ti khon mcmohd20, bn cn thng bo lnh sau:
$ userdel -r mcmohd20
Nu bn mun gi th mc chnh cho cc mc sau, bn khng s dng ty chn .r. Bn c th g

b th mc chnh vo ln sau.
Hiu nng h thng trong Unix

Mc ch ca chng hng dn ny l gii thiu phn tch hiu nng bng cc cng c c sn
gim st v qun l hiu nng trn cc h thng Unix, v cung cp mt nguyn tc ch o
chung v cch pht hin v sa cc vn v hiu nng trong mi trng Unix.
Unix c cc kiu ngun chnh sau m cn c gim st kim tra v c bt ln:
CPU
B nh
Khng gian a
Cc dy dn giao tip
I/O Time
Thi gian mng
Cc chng trnh ng dng
Page 137
Cc thnh phn hiu nng trong Unix/Linux

Di y lit k 5 thnh phn chnh:
Thnh phn
Trng thi CPU

ngi s dng
Miu t
Lng thi gian thc t m CPU dnh chy chng trnh ca ngi s
dng trong trng thi ngi dng. N bao gm thi gian dnh chy cc
triu hi th vin, nhng khng bao gm thi gian dnh trong Kernel.
Lng thi gian m CPU dnh cho chng trnh ny trong trng thi h
Trng thi CPU thng. Tt c chng trnh I/O yu cu cc s phc v Kernel. Ngi vit
h thng
chng trnh c th nh hng gi tr ny bng cch s dng kha kt ni

I/O.
Thi gian I/O

v mng h
Lng thi gian dnh cho di chuyn d liu v phc v cc yu cu I/O.
thng
Hiu nng b
nh o
N bao gm s chuyn mch v trao i bi cnh.
Chng trnh
Thi gian dnh cho chy cc chng trnh khc khi h thng khng phc
ng dng
v ng dng ny bi v ng dng khc hin ti ang c trong CPU.
Cc cng c hiu nng trong Unix/Linux

Unix cung cp cc cng c quan trng o lng v tinh chnh hiu nng h thng:
Lnh
Miu t
nice/renice
Chy mt chng trnh vi quyn u tin c sa i trc.
netstat
In cc kt ni mng h thng, bng nh tuyn, cc thng k giao din,

cc kt ni n danh v cc thnh vin multicast.
Page 138
time
Lng thi gian mt lnh n hoc cung cp cch s dng ngun.
uptime
Trung bnh ti h thng (SLA System Load Average)
ps
Bo co mt nh chp nhanh (snapshot) ca cc tin trnh hin ti.
vmstat
Bo co cc thng k v b nh o.
gprof
Hin th gi th d liu profile.
prof
Tin trnh profile
top
Hin th cc nhim v ca h thng.
Bn c th truy cp vo Trang tr gip (Manpage Help) kim tra c php y cho mi lnh
c cp y.
H thng ghi log trong Unix

Cc h thng Unix c h thng ghi log rt mnh v linh ng, m cho bn kh nng ghi li hu
ht mi th bn c th tng tng v sau thao tc s ghi log ny truy xt thng tin bn yu
cu.
Rt nhiu phin bn ca Unix cung cp mt phng tin d dng ghi log vi mc ch chung gi l
syslog. Mi chng trnh cn thng tin ghi log c gi ti syslog.
syslog trong Unix l mt host c th nh hnh, l phng tin ghi log h thng ng dng. H
thng
dng
mt
tin
trnh
ghi
log
thng
trung
tm
chy
chng
trnh/etc/syslogd hoc /etc/syslog.

Hot ng ca h thng ghi log l khng phc tp. Cc chng trnh gi ca vo ghi log
tisyslogd, m tham vn t file nh cu hnh /etc/syslogd.conf hoc /etc/syslog v khi mt kt ni
c tm thy, n vit thng tin ghi log ti file ghi log yu cu.
Bng di lit k 4 mc syslog c bn m bn nn hiu:
Page 139
Mc
Miu t
Facility
Du hiu nhn din c s dng miu t ng dng hoc tin trnh m
(phng tin)
trnh ti thng bo log. Cc v d l mail, kernel, v ftp.
Priority (quyn Mt ch dn quan trng ca thng bo. Cc mc c xc nh trong syslog

u tin)
nh mt guideline, t vic chnh li thng tin ti cc s kin quan trng.
Selector (b
Mt s kt ni ca mt hoc nhiu phng tin v mc . Khi mt s kin
chn)
mi n kt ni vi mt b chn, mt hnh ng c thc hin.

iu g xy ra khi mt thng tin mi n kt ni vi mt b chn. Cc hnh
Action (hnh
ng c th vit thng tin ti file ghi log, phn x thng tin ti mt bn iu
ng)
khin hoc thit b khc, vit thng bo ti h thng ghi log ca ngi s dng
hoc gi thng bo cng vi my ch syslog khc.
Cc phng tin syslog trong Unix/Linux

Di y l cc phng tin c sn cho b chn. Khng phi tt c cc phng tin c mt trn
tt c cc phin bn ca Unix.
Facility
auth
authpriv
console
Miu t
Cc hot ng lin quan n yu cu tn v mt khu (getty, su,
login)
Tng t nh auth nhng ghi log ti mt file m ch c th c
c bi nhng ngi dng c chn.
S dng bt cc thng bo m thng trc tip gi ti bn iu
khin h thng.
cron
Cc thng bo t ngi lp h thng cron.
daemon
H thng daemon nhn tt c.
Page 140
ftp
Cc thng bo lin quan n h thng ftp deamon.
kern
Cc thng bo kernel.
local0.local7
Cc phng tin ni b c xc nh cho mi site.
lpr
Cc thng bo t dng h thng in.
mail
Cc thng bo lin quan ti h thng mail.
mark
news
Cc s kin gi c s dng to timestamp trong cc file h

thng.
Cc thng bo lin quan ti mng li giao thc tin tc (network
news protocol)
ntp
Cc thng bo lin quan n giao thc thi gian mng.
user
Cc tin trnh ngi dng thng thng.
uucp
H thng ph UUCP.
Cc quyn u tin syslog trong Unix/Linux

Cc quyn u tin syslog c tng hp di bng sau:
Quyn u tin
emerg
alert
crit
Miu t
Tnh trng khn cp, nh mt s ngng hot ng h thng sp xy ra,
thng c thng bo ti tt c ngi dng.
Tnh trng m nn c chnh li cho ng ngay lp tc, nh mt d
liu h thng b h hng.
Tnh trng nghim trng, nh li phn cng.
Page 141
err
Cc li thng thng.
warning
Cnh bo.
notice
Tnh trng m khng l li, nhng c l nn c thc hin theo mt

cch c bit.
info
Thng bo mang tnh thng tin.
debug
Cc thng bo m c s dng khi chnh li cc chng trnh.
none
Cc mc gi to c s dng xc nh khng log cc thng bo.
S kt ni ca cc phng tin v cc mc cho bn kh nng thy r v nhng g c ghi log

v ni m cc thng tin bt ngun.
Khi mi chng trnh gi cc thng bo ca n mt cch nghim tc ti h thng ghi log, trnh ghi
log to cc quyt nh v nhng g theo di n v nhng g loi b n cc mc c xc
nh trong b chn.
Khi bn xc nh mt mc, h thng s theo di mi th ti mc v cao hn.
Tp /etc/syslog.conf trong Unix/Linux

Tp ny iu khin ni cc thng bo c log. Mt tp syslog.conf c trng c th trng ging
nh th ny:
*.err;kern.debug;auth.notice /dev/console
daemon,auth.notice
/var/log/messages
lpr.info
/var/log/lpr.log
mail.*
/var/log/mail.log
ftp.*
/var/log/ftp.log
auth.*
@prep.ai.mit.edu
auth.*
root,amrood
netinfo.err
/var/log/netinfo.log
install.*
/var/log/install.log
*.emerg
Page 142
*.alert
|program_name
mark.*
/dev/console
Mi dng ca file cha hai phn:
Mt b chn thng bo m xc nh loi thng bo log. V d, tt c cc thng bo li

hoc tt c cc thng bo chnh li t kernel.
Mt trng hnh ng m ni nhng g nn c lm vi thng bo . V d, t n trong

mt file hoc gi thng bo ti terminal ca mt ngi dng.
Di y l cc im ng ch cho s nh cu hnh trn:
Cc b chn thng bo gm hai phn: mt phng thc v mt quyn u tin. V

d, kern.debug chn tt c cc thng bo debug (c Priority) c to bi kernel (c
Facility).
B chn thng bo kern.debug chn tt c cc quyn u tin m u tin hn chnh li.
Mt du sao * trong v tr hoc ca phng thc hoc quyn u tin m ch rng tt c. V

d, *.debug ngha l tt c cc thng bo chnh li, trong khi kern.* ngha l tt c cc thng
bo c to ra bi kernel.
Bn cng c th s dng cc du phy xc nh nhiu phng thc. Hai hoc nhiu b

chn c th c nhm li vi nhau bng cch s dng mt du chm phy (;).
Cc hnh ng ghi log trong Unix/Linux

Trng hnh ng xc nh mt trong 5 hnh ng sau:
1. Thng tin ghi log ti mt file hoc mt thit b. V d, /var/log/lpr.log hoc /dev/console.
2. Gi mt thng bo ti mt ngi s dng. Bn c th xc nh nhiu tn s dng bng vic
ngn cch chng bi du phy (v d root, amrood).
3. Gi mt thng bo ti tt c ngi dng. Trong trng hp ny, trng hnh ng bao
gm mt du *.
4. Gi mt thng bo thng qua pipe ti mt chng trnh. Trong trng hp ny, chng
trnh c xc nh sau k hiu pipe (|).
Page 143
5. Gi thng bo ti syslog trn mt host khc. Trong trng hp ny, trng hnh ng bao
gm mt tn host, c t trc bi mt du hiu (v d: @tutorialspoint.com)
Lnh logger trong Unix/Linux

Unix cung cp lnh logger, m l mt lnh thc s hu ch gii quyt h thng ghi log. Lnh
logger gi cc thng bo ghi log ti syslogd deamon, v do kch thch h thng ghi log.
iu ny c ngha l chng ta c th kim tra t dng lnh ti bt c thi gian no.
Lnhlogger cung cp mt phng thc thm cng vo mt dng ti h thng ghi log file t
dng lnh.
nh dng ca lnh l:
logger [-i] [-f file] [-p priority] [-t tag] [message]...
Di y l chi tit v cc tham s.
Chc nng
Miu t
-f filename
S dng ni dung ca tn file nh thng bo log.
-i
log ID tin trnh ca tin trnh logger vi mi dng.

Nhp thng bo vi quyn u tin c xc nh (li vo b chn c xc
-p priority
nh); quyn u tin thng bo c th c xc nh dng s hoc nh l cp

phng thc.quyn u tin. Quyn u tin mc nh l user.notice.
-t tag
message
nh du mi dng c thm ti h thng log vi th xc nh.

Cc tham s chui m ni dung c kt ni cng nhau theo th t xc nh,
ring r bi khong trng.
Bn c th s dng trang Trang tr gip (Manpage Help) kim tra c php ca cc lnh ny.
S lun phin log trong Unix/Linux
Page 144
Cc log file c thin hng tng ln rt nhanh v chim mt khong ln ca khng gian a.
cho
php kh
nng lun
phin
log, hu ht phin
bn
s dng
cc
cng
nhnewsyslog hoc logrotate.

Nhng cng c ny nn c gi trn mt khong khng gian thng xuyn bng cch s dng
cron deamon. Bn truy cp vo chng Trang tr gip (Manpage Help) bit thm chi tit v
newsyslog hoc logrotate.
Cc v tr log quan trng trong Unix/Linux

Tt c ng dng h thng to cc tp log trong /var/log v cc thc mc ph ca n. Di y l
mt s ng dng quan trng v cc th mc log tng ng ca chng.
ng dng
Th mc
httpd
/var/log/httpd
samba
/var/log/samba
cron
/var/log/
mail
/var/log/
mysql
/var/log/
Signal v Trap trong Unix/Linux

Signals l cc tn hiu ngt phn mm c gi ti mt chng trnh bo rng c mt s kin
nghim trng xy ra. Cc s kin ny c th rt a dng t cc yu cu ngi s dng truy cp
vo b nh bt hp php. Mt vi signal, nh signal ngt, ch rng mt ngi s dng i hi
chng trnh lm ci g m khng trong s kim sot.
Bng di y lit k cc signal thng thng m bn c th bt gp hoc mun s dng n trong
cc chng trnh ca bn:
Tn signal
S
hiu
Miu t
Page 145
signal
Tr hon vic kim tra trn qun l terminal hoc s dng ca qun l
SIGHUP
SIGINT
c thng bo nu ngi s dng gi mt tn hiu ngt (Ctrl+C).
SIGQUIT
c thng bo nu ngi s dng gi mt tn hiu b (Ctrl+D).
SIGFPE
SIGKILL
SIGALRM
14
Tn hiu bo s ln thc hin (Alarm Clock).
SIGTERM
15
Tn hiu kt thc phn mm (c gi bi sigkill theo mc nh).
tin trnh.
c thng bo nu mt hot ng thuc v ton khng hp php

c th chy.
Nu mt tin trnh nhn signal ny, n phi thot ra ngay lp tc v
s khng thc hin cc hot ng lm sch.
Danh sch cc signal trong Unix/Linux

C mt cch d dng lit k tt c cc signal c h tr bi h thng ca bn. Ch cn thng
bo lnh kill -l v n s hin th tt c cc signal c h tr.
$ kill -l
1) SIGHUP
2) SIGINT
3) SIGQUIT
4) SIGILL
5) SIGTRAP
6) SIGABRT
7) SIGBUS
8) SIGFPE
9) SIGKILL
10) SIGUSR1
11) SIGSEGV
12) SIGUSR2
13) SIGPIPE
14) SIGALRM
15) SIGTERM
16) SIGSTKFLT
17) SIGCHLD
18) SIGCONT
19) SIGSTOP
20) SIGTSTP
21) SIGTTIN
22) SIGTTOU
23) SIGURG
24) SIGXCPU
25) SIGXFSZ
26) SIGVTALRM
27) SIGPROF
28) SIGWINCH
29) SIGIO
30) SIGPWR
31) SIGSYS
34) SIGRTMIN
35) SIGRTMIN+1
36) SIGRTMIN+2
37) SIGRTMIN+3
38) SIGRTMIN+4
39) SIGRTMIN+5
40) SIGRTMIN+6
41) SIGRTMIN+7
42) SIGRTMIN+8
43) SIGRTMIN+9
44) SIGRTMIN+10 45) SIGRTMIN+11 46) SIGRTMIN+12
Page 146
47) SIGRTMIN+13 48) SIGRTMIN+14 49) SIGRTMIN+15 50) SIGRTMAX-14

51) SIGRTMAX-13 52) SIGRTMAX-12 53) SIGRTMAX-11 54) SIGRTMAX-10
55) SIGRTMAX-9
56) SIGRTMAX-8
57) SIGRTMAX-7
58) SIGRTMAX-6
59) SIGRTMAX-5
60) SIGRTMAX-4
61) SIGRTMAX-3
62) SIGRTMAX-2
63) SIGRTMAX-1
64) SIGRTMAX
Danh sch thc t trn ca signal l a dng v khc nhau gia Solaris, HP-UX v Linux.
Cc hot ng mc nh trong Unix/Linux

Mi signal c mt hot ng mc nh lin kt vi n. Hot ng mc nh vi mt signal l hot
ng m mt script hoc mt chng trnh thc hin khi n nhn c mt signal.
Mt trong s cc hot ng mc nh c th l:
Kt thc tin trnh
B qua signal
Kt xut li nh. N to mt file gi l core (li) cha hnh nh b nh ca tin trnh khi n
nhn c signal
Dng tin trnh
Tip tc tin trnh b dng
Gi cc signal trong Unix/Linux

C mt vi phng thc trong vic gi cc signal ti mt chng trnh hoc mt script. Mt trong
nhng phng thc ph bin nht l cho ngi s dng g phm Ctrl +C hoc phm dng trong
khi mt script ang chy.
Khi bn nhn phm Ctrl+C, mt SIGINT c gi ti script v khi mi hnh ng mc nh xc
nh s kt thc script.
Phng thc ph bin khc gi signal l s dng lnh kill m c c php nh sau:
$ kill -signal pid
y, signal l hoc s hoc tn ca signal gi v pid l ID tin trnh m signal nn c gi

ti. V d:
Page 147
$ kill -1 1001
Gi HUP hoc signal dng ti mt chng trnh m ang chy vi ID tin trnh l 1001. gi
mt kill signal ti tin trnh ging nh vy, bn s dng lnh sau:
$ kill -9 1001
N s hy tin trnh ang chy c ID tin trnh 1001.
Trap signal trong Unix/Linux

Khi bn nhn phm Ctrl+C hoc phm dng ti terminal ca bn trong sut qu trnh chy mt
chng trnh shell, thng thng th chng trnh b ngay lp tc kt thc, v dng nhc lnh
xut hin tr li. Vic ny c th s khng lun lun lm bn thch th. V d, bn c th s li
hng lot cc tp tin tm thi m khng c dn sch.
Trap signal l kh d dng, v lnh trap c c php nh sau:
$ trap commands signals
y, command c th l bt c lnh Unix c hiu lc no, hoc ngay c l mt chc nng

nh ngha ca ngi s dng, v signal c th l danh sch cc signal m bn mun trap.
C 3 cch s dng ph bin trap trong shell script:
1. Dn sch cc file tm thi
2. B qua cc signal
Dn sch cc file tm thi trong Unix/Linux

Nh mt v d ca lnh trap, di y ch cch bn c th g b mt vi file v sau thot khi
nu ai c gng b d chng trnh t terminal.
$ trap "rm -f $WORKDIR/work1$$ $WORKDIR/dataout$$; exit" 2
T im trong chng trnh shell m trap ny c thc thi, hai tp work1$$ v dataout$$s t
ng b d b nu signal s 2 c nhn bi chng trnh.
V th nu ngi s dng ngt vic thi hnh ca chng trnh th sau trap ny c chy, bn
c th c m bo chc chn rng hai file ny s c dn sch s. Lnh exit m theo sau
Page 148
bi rm l cn thit bi v khng c n th chng trnh s tip tc chy ti im m n dng li khi

signal c nhn.
Signal s 1 c to tr hon: hoc ai c tnh treo dng hoc dng mt cch ngu nhin b
ngt kt ni.
Bn c th chnh sa trap trc cng g b hai file xc nh trong trng hp ny bng
cch thm signal s 1 ti danh sch cc signal.
$ trap "rm $WORKDIR/work1$$ $WORKDIR/dataout$$; exit" 1 2
By gi nhng file ny s b g b nu dng b treo hoc nu phm Ctrl+C c nhn.

Lnh c xc nh trap phi c bao quanh trong trch dn nu chng cha nhiu hn mt
lnh. Bn cng lu rng shell qut dng lnh ti thi im m lnh trap c chy v cng thc
hin qut ln na khi mt trong cc signal c lit k c nhn.
V th trong v d trc, gi tr ca WORKDIR v $$ s c thay i ti thi gian m lnh trap
c chy. Nu bn mun s thay i ny xy ra ti thi im m hoc signal s 1 hoc s 2
c nhn, bn c th t cc lnh bn trong trch dn n nh sau:
$ trap 'rm $WORKDIR/work1$$ $WORKDIR/dataout$$; exit' 1 2
B qua cc signal trong Unix/Linux

Nu lnh c lit k cho trap l null, th signal c xc nh s b b qua khi c nhn. V d,
lnh sau:
$ trap '' 2
Xc nh rng signal ngt b b qua. Bn c th mun b qua cc signal c th no khi thc

hin mt s hot ng m m khng mun b ngt. Bn c th xc nh nhiu signal b b qua nh
sau:
$ trap '' 1 2 3 15
Ghi nh rng i s th nht phi c xc nh cho mt signal b b qua v cch trn l khng
cn bng vi cch vit sau, m cch vit sau ny c ngha ring ca n:
$ trap
Page 149
Nu bn b qua mt signal, tt c cc shell ph cng b qua signal . Tuy nhin, nu bn xc

nh mt hnh ng c thc hin khi nhn c signal th tt c cc shell ph cng s vn thc
hin hnh ng khi nhn c signal .
Thit lp li trap trong Unix/Linux

Sau khi bn thay i cc hnh ng mc nh khi nhn c mt signal, bn c th thay i tr
li ln na vi trap, nu bn n gin b qua i s u tin nh sau:
$ trap 1 2
N thit lp li hnh ng c thc hin khi nhn c signal s 1 hoc 2 tr li dng mc nh.
Cc lnh hu ch trong Unix

Chng ny lit k danh sch cc lnh, bao gm c php v cc miu t ngn gn. c thm
nhiu chi tit v cc lnh ny, bn s dng:
$man command
Cc file v th mc trong Unix/Linux

Cc lnh ny cho php bn to cc th mc v iu khin cc file.
Lnh
Miu t
cat
Hin th ni dung file
cd
Thay i th mc ti dirname
chgrp
Thay i nhm file
chmod
Thay i s cho php
cp
Sao chp file ngun vo trong ni n
file
Xc nh kiu file
Page 150
find
Tm kim cc file
grep
Tm file vi biu thc quy chun
head
Hin th mt vi dng u ca file
ln
To mt link mm trn tn c
ls
Hin th thng tin v kiu file
mkdir
To mt th mc dirname mi
more
Hin th d liu trong mu c nh s trang
mv
Di chuyn (t li tn) mt tn file c thnh mt tn file mi
pwd
In th mc lm vic hin ti
rm
G b (xa) mt file
rmdir
Xa mt th mc ang tn ti
tail
In mt vi dng cui ca th mc
touch
Cp nht truy cp v thi gian chnh sa ca mt file
Thao tc d liu trong Unix/Linux

Cc ni dung ca file c th dc so snh v thay i vi cc lnh sau:
Lnh
Miu t
awk
Qut mu v tin trnh ngn ng
cmp
So snh ni dung ca 2 file
Page 151
comm
So snh d liu c phn loi
cut
Ct cc trng c chn trong mi dng ca mt file
diff
B so snh file vi sai
expand
M rng cc tab
join
Kt hp file trn mt s trng ph bin
perl
Ngn ng thao tc d liu
sed
B son lung vn bn
sort
Phn loi d liu file
split
Phn chia file thnh cc file nh hn
tr
Bin dch cc k t
uniq
Bo co cc dng c lp trong mt file
wc
Tnh ton s lng t, dng, v k t
vi
M b son vn bn vi
vim
M b son vn bn vim
fmt
B nh dng vn bn n gin
spell
Kim tra cc li chnh t vn bn
ispell
Page 152
ispell
emacs
GNU d n Emacs
ex, edit
B son dng
emacs
GNU d n Emacs
emacs
GNU d n Emacs
Nn file trong Unix/Linux

Cc file c th c nn tit kim khng gian. Cc file b nn c th c to v thc hnh vi
cc lnh di.
Lnh
Miu t
compress
Nn cc file
gunzip
B nn cc file
gzip
Phng thc nn thay th GNU
uncompress
B nn cc file
unzip
Lit k, kim tra v gii nn cc file b nn trong ti liu ZIP
zcat
Ni v lin kt cc file b nn
zcmp
So snh cc file b nn
zdiff
So snh cc file b nn
zmore
Lc file quan st crt ca cc vn bn b nn
Page 153
Nhn thng tin trong Unix/Linux

Cc ti liu tra cu v cc s tay Unix a dng c sn trn mng trc tuyn. Cc lnh shell sau s
cung cp thng tin cho bn:
Lnh
Miu t
apropos
t v tr cc lnh bng t kha tra cu.
info
Hin th thng tin lnh trn trang trc tuyn
man
Hin th s tay cc trang trc tuyn
whatis
Tm kim d liu whatis cho cc t y .
yelp
B thm tra s gip GNOME
Giao tip mng h thng trong Unix/Linux

Cc lnh sau c s dng gi v nhn cc file t mt host ni b ti mt host iu khin t xa
trn Th gii.
Lnh
Miu t
ftp
Chuyn file ti chng trnh
rcp
iu khin t xa vic sao chp file
rlogin
ng nhp t xa ti mt Unix host
rsh
iu khin t xa shell
tftp
Chng trnh truyn ti file thng
telnet
To kt ni terminal ti host khc
Page 154
ssh
Bo an shell terminal hoc s kt ni lnh
scp
Bo an shell t vic sao chp file t xa
sftp
Bo an shell t gi file ti chng trnh
Mt trong s cc lnh trn c th b hn ch ti my tnh ca bn v cc l do bo mt.
Cc thng bo gia cc ngi s dng trong

Unix/Linux
H thng Unix h tr cc thng bo hin th trn mn hnh ti ngi s dng khc v gi mail t
ng trn ton Th gii.
Lnh
Miu t
evolution
Cng c iu khin mail GNU trn Linux
mail
Chng trnh gi v c mail n gin
mesg
Cho php hoc t chi nhn cc thng bo
parcel
Gi cc file ti ngi dng khc
pine
Tin ch vdu-base mail
talk
Ni chuyn vi ngi s dng khc
write
Vit thng bo ti ngi s dng khc
Cc chng trnh tin ch trong Unix/Linux

Bng di l cc cng c v ngn ng m c sn da trn nhng g bn ci t trn h thng
Unix ca bn:
Lnh
Miu t
Page 155
dbx
Chng trnh chnh li Sun
gdb
Chng trnh chnh li GNU (GNU debugger)
make
Duy tr cc nhm chng trnh v cc chng trnh bin dch
nm
In danh sch tn chng trnh
size
In kch c ca chng trnh
strip
D b bng k t v t li v tr cc bit
cb
B vit ng (beautifier) chng trnh C
cc
B bin dch ANSI C cho cc h thng Suns SPARC
ctrace
Chng trnh chnh li C
gcc
B bin dch GNU ANSI C
indent
Sp ch tht vo v nh dng ca ngun chng trnh C
bc
B x l ngn ng s hc tng tc
gcl
GNU Common Lisp
perl
Ngn ng mc ch chung
php
Trang web ngn ng c nhng
py
B phin dch ngn ng Python
asp
Trang web ngn ng c nhng
Page 156
CC
B bin dch C++ cho cc h thng Suns SPARC
g++
B bin dch GNU C++
javac
B bin dch JAVA
appletvieweir
B thm tra vi m JAVA
netbeans
Tch hp mi trng pht trin JAVA trn Linux
sqlplus
Chy b phin dch Oracle SQL
sqlldr
Chy b ti d liu Oracle SQL
mysql
Chy b phin dch mysql SQL
Cc lnh hn hp trong Unix/Linux

Di y l cc lnh v thng tin thay i v h thng:
Lnh
Miu t
chfn
Thay i thng tin lnh finger ca bn
chgrp
Thay i s hu nhm ca mt file
chown
Thay i ngi s hu
date
In ngy
determin
T ng tm kim kiu terminal
du
In dung lng a s dng
echo
Phn x cc i s ti cc chc nng tiu chun
Page 157
exit
Thot khi h thng
finger
In thng tin v nhng ngi s dng ng nhp vo
groupadd
To mt nhm ngi s dng
groups
Ch cc thnh vin ca nhm
homequota
Ch hn ngch v dung lng file s dng
iostat
Bo co cc thng k I/O
kill
Gi mt signal ti mt chng trnh
last
Hin th cc ng nhp cui ca nhng ngi s dng
logout
Thot khi Unix
lun
Lit k cc tn ngi dng hoc ID ng nhp
netstat
Ch trng thi ca mng h thng
passwd
Thay i mt khu ca ngi s dng c nhn
passwd
Thay i mt khu ng nhp ca bn
printenv
Hin th gi tr ca mt bin shell
ps
Hin th trng thi ca cc tin trnh hin ti
ps
In cc thng k trng thi ca tin trnh
quota -v
Hin th dung lng s dng a v cc gii hn
Page 158
reset
Thit lp li ch terminal
script
Gi scritp ca khu vc terminal
script
Lu gi kt qu u ra ca mt lnh hoc mt tin trnh
setenv
Thit lp cc bin mi trng
stty
Thit lp cc chc nng terminal
time
Thi gian ca mt lnh
top
Hin th tt c cc tin trnh h thng
tset
Thit lp ch terminal
tty
In tn terminal hin ti
umask
Ch cc s cho php m c cung cp quan st cc file theo

mc nh
uname
Hin th tn ca h thng hin ti
uptime
Nhn thi gian hot ng ca h thng
useradd
To mt ti khon s dng c nhn
users
In tn ca nhng ngi s dng ng nhp
vmstat
Bo co cc thng k b nh thc
Ch nhng g m ngi dng ng nhp ang thc hin
who
Lit k danh sch nhng ngi dng ng nhp
Page 159
Hm ton hc c sn trong Shell

Hu ht cc phn ca Bi hng dn ch yu xy dng trn Bourne Shell nhng trang ny lit k
tt c cc hm ton hc c xy dng c sn trong Korn Shell.
Korn Shell cung cp s truy cp ti b thit lp tiu chun ca cc hm ton hc. Chng c gi
bng cch s dng c php gi hm C:
Hm
Miu t
abs
Gi tr tuyt i
log
Logarit t nhin
acos
Hm arcos
sin
Hm sin
asin
Hm arcsin
sinh
Hm sin hyperbolic
cos
Hm cos
sqrt
Cn bc hai
cosh
Hm cos hyperpolic
tan
Hm tan
exp
Hm m
tanh
Hm tan hyperpolic
int
Phn nguyn
Page 160
Ti liu tham kho Unix/Linux

Di y l danh sch cc ngun hu ch v Unix/Linux. Bn nn tham kho chng hiu su
hn nhng ch chng ti cp trong lot bi ny.
Tutorialspoint Lot bi hng dn ca chng ti xy dng da trn ngun ny.
Bell Labs Qu trnh to H iu hnh UNIX. Cung cp tng quan v lch s ca H iu

hnh UNIX.
BSD UNIX FreeBSD l mt H iu hnh UNIX bc cao cho Server, desktop, v cc

Platform hin i.
Linux Online Linux l mt H iu hnh Unix-type min ph c to ln u bi Linus

Torvalds vi s h tr ca cc nh lp trnh trn ton Th gii.
Unix @ Wikipedia Mt miu t ngn gn v H iu hnh Unix.
The Unix Forums Mt din n cho nhng ngi yu Unix. Chia s tng v suy ngh
ca bn vi cc Chuyn gia v Unix.
Page 161

Tài Liệu UNIX Tiếng Việt

Uploaded by

Document Information

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Tài Liệu UNIX Tiếng Việt

Uploaded by

Copyright:

Available Formats

http://vietjack.com/unix/index.

Tng quan v Unix/Linux

Unix/Linux c pht trin ln u tin bi mt nhm cc nhn vin AT&T ti phng th

http://vietjack.com/ Trang chia s cc bi hc online min ph

Nhiu ngi c th s dng mt my tnh Unix cng mt lc; v th Unix c gi l h

Mt ngi s dng c th chy nhiu chng trnh cng mt lc; v th Unix c gi l a

Khi nim chnh m c thng nht trong tt c cc phin bn Unix gm 4 c s sau:

Kernel: Kernel l tri tim ca h iu hnh. N tng tc vi phn cng v hu ht nhim

Shell: Shell l mt tin ch m x l cc yu cu ca bn. Khi bn g mt lnh ti terminal

http://vietjack.com/ Trang chia s cc bi hc online min ph

Cc lnh v cc tin ch: C rt nhiu lnh v tin ch m bn c th s dng trong cng

Files v th mc: Tt c d liu trong Unix c t chc trong cc file. Tt c cc file

Khi ng h thng trong Unix/Linux

ng nhp h thng Unix/Linux:

http://vietjack.com/ Trang chia s cc bi hc online min ph

Bn s c cung cp vi mt lnh nhc (i khi c gi l lnh $) m ti bn s nhp tt c

Thay i mt khu trong Unix/Linux

http://vietjack.com/ Trang chia s cc bi hc online min ph

Ghi ch: Ti t du * vo v tr ch cho bn a im bn cn nhp mt khu c v mi. Ngoi

Lit k th mc v file trong Unix/Linux:

4096 Dec 25 09:59 uml

5341 Dec 25 08:38 uml.jpg

y phn nhp bt u vi d biu din cc th mc. V d nh uml, univ v urlspedia l cc

http://vietjack.com/ Trang chia s cc bi hc online min ph

Hy th n trn h thng ca mnh. Lnh ny lit k cc tn ti khon lin kt vi s ng nhp

Ai ng nhp trong Unix/Linux?

ttyp2 Oct 4 09:08 (calliope)

ttyp4 Oct 8 12:09 (dent)

Bn hy th lnh w trn h thng ca bn kim tra kt qu u ra. Lnh ny s lit k mt s

Thot khi chng trnh trong Unix/Linux

thot khi chng trnh:

ng h thng trong Unix/Linux

ng h thng ngay lp tc.

h thng trc khi shutdown.

Qun l File trong Unix

http://vietjack.com/ Trang chia s cc bi hc online min ph

2. Directory: Th mc, lu gi c cc file thng v c bit. Tng t vi cc th mc

Lit k cc file trong Unix/Linux

Lnh ls h tr ty chn -l gip bn nhn c nhiu thng tin hn v cc file c lit k.

4096 Dec 25 09:59 uml

5341 Dec 25 08:38 uml.jpg

http://vietjack.com/ Trang chia s cc bi hc online min ph

drwxr-xr-x 11 amrood amrood

Di y l cc thng tin v tt c cc ct c lit k:

http://vietjack.com/ Trang chia s cc bi hc online min ph

File lin kt k t. Kt ni trn bt k mt file thng no.

Pipe c t tn. Mt c cu giao tip lin tin trnh.

Socket c s dng cho giao tip lin tin trnh.

Cc siu k t trong Unix/Linux

Hin th tt c cc file m tn bt u vi cp k t ch v kt thc vi .doc.

Di y k t * thc hin kt ni vi bt k k t no. Nu bn mun hin th tt c cc file kt

Cc file n trong Unix/Linux

.profile: l script khi to Bourne shell (sh)

.kshrc: l script khi to Korn shell (ksh)

.cshrc: l script khi to C shell (csh)

.rhosts: l file nh hnh shell iu khin t xa.

http://vietjack.com/ Trang chia s cc bi hc online min ph

Du chm n (.): i din cho th mc hin ti

Du chm kp (..): i din cho th mc gc.

To cc file trong Unix/Linux

Lnh trn s m mt file vi tn cung cp. Bn s cn nhn phm i tin vo ch chnh

Khi thc hin xong, bn lm theo cc bc sau:

Nhn phm esc thot khi ch ny

Nhn t hp phm Shift+ZZ thot khi file hon ton.