centos các câu lệnh linux căn bản

Lnh Init trong linux- Run level 0 (init 0): ch tt my.- Run level 1 (init 1): ch ny ch s dng c 1 ngi dng.- Run level 2 (init 2): ch a ngi dng nhng khng c dch v NFS.- Run level 3 (linit 3): ch a ngi dng, c y cc dch v.- Run level 4 (linit 4): cha c s dng.- Run level 5 (linit 5): ch ha.- Run level 6 (linit 6): khi ng li my.- C php: # init- V d:+ Dng lnh init 0 tt my:# init 0+ khi ng li my tnh ta dng lnh:# init 6+ Khi ang ch ha ta c th chuyn sang ch dng lnh (text mode) bng cch dng lnh:# init 3+ Ngc li, khi ang ch dng lnh ta c th chuyn sang ch ha bng cch dng lnh:# init 5- Tp tin cu hnh: /etc/inittabKhi khi ng my tnh, Linux s c trong tp tin /etc/inittab chn ch khi ng. C th l dng id::initdefault:iu ChnhXp Bi

26-11-2007, 08:07 PM

lehoaiITBannedTham gia ngy: Oct 2007Ni c ng: C Mau Si GnBi gi: 968

Cc cu lnh Linux cn bn

Cho cc bn y la mt s lnh c bn trong h h iu hnh LINUX. Khi no chng ta dng nhng lnh ny? l khi chng ta thc hin Remote config, lm vic trn my nhng m qua giao din Command line qua ca s Terminal, hay n gin l nhng ai thch lm vic qua CLI. Cc lnh ny l cc lnh ph bin nhng m ty vo OS m chng s c i ch khc nhau. Chng ta s im qua mt s lnh sau:

Cc Lnh V Khi To

rlogin: dng iu khin hoc thao tc lnh trn mt my khc

exit : thot khi h thng (Bourne-Shell)

logout: thot khi h thng C-Shell

id : ch danh ca ngi s dng

logname: tn ngi s dng login

man : gip

newgrp: chuyn ngi s dng sang mt nhm mi

psswd: thay i password ca ngi s dng

set : xc nh cc bin mi trng

tty : t cc thng s terminal

uname: tn ca h thng (host)

who : cho bit nhng ai ang thm nhp h thng

Lnh V Trnh Bo Mn Hnh

echo: hin th dng k t hay bin

setcolor: t mu nn v ch ca mn hnh

Lnh V Desktop bc: tnh biu thc s hc

cal : my tnh c nhn

date: hin th v t ngy

mail: gi - nhn th tn in t

mesg : cm/cho php hin th thng bo trn mn hnh (bi write/ hello)

spell : kim tra li chnh t

vi : son tho vn bn

write/hello: cho php gi dng thng bo n nhng ngi s dng trong h thng

Lnh V Th Mc cd : i th mc

cp : sao chp 2 th mc

mkdir: to th mc

rm : loi b th mc

pwd: trnh by th mc hin hnh

Lnh v tp tin more: trnh by ni dung tp tin

cp : sao chp mt hay nhiu tp tin

find: tm v tr ca tp tin

grep : tm v tr ca chui k t trong tp tin

ls: trnh by tn v thuc tnh ca cc tp tin trong th mc

mv : di chuyn/i tn mt tp tin

sort: sp th t ni dung tp tin

wc : m s t trong tp tin

cat: hin th ni dung moat tp tin

vi: son tho hoc sa i ni dung tp tin

Lnh v qun l qu trnh: kill: hy b mt qu trnh

ps : trnh by tnh trng ca cc qu trnh

sleep: ngng hot ng mt thi gian

Cc Lnh V Phn Quyn chgrp: chuyn ch quyn tp tin, th mc t mt nhm sang mt nhm khc

chmod : thay i quyn s hu ca tp tin hay th mc

chown : thay i ngi s hu tp tin hay th mc

Lnh V Kim Sot In cancel : ngng in

lp : in ti liu ra my in

Lnh v h thng:top: Xem trng thi v h thng v cc process ang chy tng t nh Task Manager trong Windows.shutdown -h now tt my tnhshutdown -r now : khi ng liRing cho RedHat Theo ti c bit th Vit Nam hin nay HDH Linux ph bin nht l Redhat nn y chng xin trnh by thm v rpm

install mt package:rpm -ivh

upgrade mt package:rpm -Uvh

uninstall mt package:rpm -e

bit mt package c install hay charpm -q

filename y c th l 1 file hoc nhiu file vi format rpm

Cc lnh thng c thm rt nhiu cc thng s i theo. bit thm v chi tit v chng cc bn c th dng lnhman command hoc command --help vi command l lnh cn xem.

26-11-2007, 08:10 PM

lehoaiITBannedTham gia ngy: Oct 2007Ni c ng: C Mau Si GnBi gi: 968

Tip theo chng ta s i su vo chi tit mt s lnh. Ti liu c son v chnh sa. Nn c g sai st mong cc bn gp .

x dng dng lnh u tin bn cn bt command shell ln, ci ny tng t nh MS DOS ca windows.Ty theo h iu hnh m bn ang dng l g m n s l Konsole hay Terminal ... Sau bn cn c quyn root bng lnh su (hay sudo trong Ubuntu). Khi bn c quyn root du nhc trong ca s command shell thng l:[root@duchai ~]#Lnh thng k dung lng th mc Linux[root@unix1 webhostings]# du -sh *Bn xem thng tin v user mnh ang login bng lnh: id

[root@duchai ~]# iduid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(di sk),10(wheel) context=root:system_r:unconfined_t:SystemLow-SystemHigh

Cc ch s uid v gid s cho bit quyn hn ca bn trn h thng. 0 l quyn cao nht ri.By gi bn mun login vi user mi bn s dng lnh : useradd

[root@duchai ~]# useradd kikicoco

vy l bn c user mi l kikicoco trong h thng.Lnh useradd c rt nhiu tham s khc nhau, xem chi tit bn dng lnh man

[kikicoco@duchai root]$ man useradd

Lc trc khi to user kikicoco chng ta cha to mt khu, by gi to mt khu cho user ny, bng lnh passwd.

[root@duchai ~]# passwd kikicoco

Changing password for user kikicoco.

New UNIX password:

Sau nhp mt khu vo. chuyn sang user ny bn dng lnh : su

[root@duchai ~]# su kikicoco

bn kim tra li bng cch nh lnh : id

[kikicoco@duchai root]$ iduid=501(kikicoco) gid=501(kikicoco) groups=501(kikicoco) context=root:system_r:unconfined_t:SystemLow-SystemHigh

Tip theo l cc lnh c bn vi th mc :Bn cn bit hin ti ang th mc no bn dng :pwd

[kikicoco@duchai root]$ pwd/root

Vy l user kikicoco ang th mc /root.Cc lnh v th mc trn unix tng t nh trn MS DOS ca windows, ch c mt s im khc bit.Lnh ls s tng ng vi dir.

Thc hnh :

[kikicoco@duchai root]$ lsls: .: Permission denied

Vy l li ri, user kikicoco khng c quyn s dng lnh ls. Lc trc khi to user ti cha thm shell cho user nn user s khng c quyn s dng lnh ny. By gi ti s thm shell cho user.Trc tin cn chuyn v user root bng lnh : su root, n s hi mt khu --> nhp mt khu ca root vo.Bn dng lnh : usermod thay i thng tin ngi dng, c php nh sau:

SYNTAXusermod [options] [user]

Bn cha bit shell nm u, nn cn dng lnh whereis xem v tr ca shell

[root@duchai ~]# whereis bashbash: /bin/bash /usr/share/man/man1/bash.1.gz

[root@duchai ~]# usermod -s /bin/bash kikicoco

Tip theo li su v user kikicoco

[kikicoco@duchai root]$ lsls: .: Permission denied

a ah, vn b li. Vy l khng phi ri, lc ny ta hiu sai. Khng phi user kikicoco khng c quyn dng shell,v vn dng c lnh pwd,... M l user kikicoco khng c quyn i vi th mc /root

y l im rt khc bit vi windows, Unix phn quyn rt cht ch da theo cc quyn :

Read - Write - Execute (c - Ghi - Thc thi)

Cc quyn ny c th hin bng k hiu : r - w - x hoc 4 - 2 -1

V vi mt th mc quyn s c phn cho : Owner - Group - others (ngi s hu - nhm - ngi khc)

xem quyn ca th mc root ta dng lnh ls vi tham s al:

[root@duchai /]# ls -al...drwxr-x--- 20 root root 4096 Nov 28 14:35 root...

Nhn vo dng trn ta s nhn c thng tin nh sau :

Owner l root

Group l root

drwxr-x--- : quyn i vi ngi dng, ch d u c ngha y l th mc, tip theo l quyn ca owner :

rwx :--> owner c ton quyn trn th mc ny, owner l root nn user root c ton quyn trn th mc ny.

r-x :--> group c quyn c v chy file, khng c quyn ghi vo th mc ny.

--- :--> others khng c quyn g i vi th mc ny.

kikicoco khng thuc group root nn khng c quyn g.

Ni thm v cch th hin quyn i vi th mc, nh trn ci ni v cch th hin cc quyn.drwxr-x--- s tng ng 740, khi th mc quyn t do nht l rwxrwxrwx - 777 tc l bt k ai cng c y cc quyn vi th mc . thay i quyn bn dng lnh CHMOD, thay i owner bn dng lnh chown, thay i group bn dng lnh chgroup.Vic t quyn hn ng s l cc k quan trng i vi mt h thng, khng ch UNIX.

26-11-2007, 08:11 PM

lehoaiITBannedTham gia ngy: Oct 2007Ni c ng: C Mau Si GnBi gi: 968

H thng th mc trn * NIX, bi nay ly v d c th l Fedora 6.

Khi th mc gc / bn nh ls s nhn c:

[root@duchai ~]# cd /[root@duchai /]# lsbin boot dev etc home lib lost+found media misc mntnet opt proc root sbin selinux srv sys tmp usr var

l cc th mc trn mt h thng Unix.

* Th mc /bin

y l thc mc cc k quan trong ca 1 h thng unix, th mc ny cha gn nh tt c cc lnh ca h thng.

* Th mc /etc

Th mc ny cha cc cc file con file ca h thng, cng nh cha thng tin v cc service cn khi ng khi h iu hnh chy.

i vi h iu hnh Linux th cc service chy lc khi ng s c t trong th mc init.d.

i vi h iu hnh SUN Solaris th cc service chy lc khi ng s c t trong th mc rc2.d.

Cc th mc trn s thay i ty h thng.

*Th mc /usr

Th mc ny cha file v chng trnh ca cc user trn h thng.

Mt iu th v trn h thng Unix l tt c u l file, k c ci gi l th mc cng l file.smile_regular

*Th mc /dev

Khi vo th mc ny nh lnh ls bn s thy rt nhiu file mu vng.

chnh l tt c cc thit b phn cng m h iu hnh dng, trn h thng Unix tt c u l file, nh ti ni trn.

V d : cng s l /dev/hda, c th c 2 loi cng IDE v SCSI, nh bn dng thng thng l IDE, SCSI thng c dng cho cc my ch v dung lng thng l 36GB, 72GB,...

*Th mc /boot

Th mc ny cha "li" ca h iu hnh hay cn gi l kernel. V d y l kernel my ca ti :

Trn h iu hnh SUN n s khng phi l th mc /boot, n l th mc /platform

bit thng tin v kernel bn dng lnh : uname -an

[root@duchai /]# uname -anLinux duchai 2.6.17-1.2157_FC5 #1 Tue Jul 11 22:55:46 EDT 2006 i686 i686 i386 GNU/Linux

* Th mc root - th mc ca user root

Khi bn dng mt user khc truy nhp vo th mc ny, bn s khng c quyn g vi th mc ny, ging nh user kikicoco phn trc.

y chnh l "Users home directory" th mc ring ca user. Trn h thnh Unix khi mt user mi to ra n s to km theo 1 th mc cho user . Thng thng cc th mc ny s nm trong th mc /home. Nhn tin y ti ni lun v th mc /home.

Th mc /home l th mc cha cc th mc ca ngi dng:

* Th mc /sbin

Th mc ny l mt th mc gii hn quyn hn, n cha cc chng trnh kiu nh th mc /bin. Nhng bn khng th lm g n n c. Ch nhng user c quyn root mi c th Shutdown cc chng trnh y.

* Th mc /tmp

Th mc ny ng nh tn ca n, n cha cc file tm do h thng sinh ra. V chia s cho bt k chng trnh no nn th mc ny c t quyn hn rt thoi mi :

drwxrwxrwt 11 root root 4096 Nov 29 04:05 tmp

Chc nng ca n cng ging nh th mc temp ca windows.

* Th mc /var

Th mc ny cha cc file c th thay i kch thc (variable size), nn thng thng trong th mc ny s cha cc database nh : mysql,.. hay mail server,...

* Th mc /lib

Lib l vit tt ca library. Th mc /lib cha cc file th vin chng trnh. Mi mt chng trnh s c th vin ring ca mnh.

* Cc th mc khc :

- /mnt

- /cdrom

- /floppy

Ban u tt c cc th mc ny u rng. Khi bn cm USB vo n s nm trong /mnt hoc bn cn mount n vo trong /mnt (ci ny ni sau happy). Khi cho a CDROM vo th d liu s c t ng mount vo th mc /cdrom. Tng t i vi floppy.Phn ny ni v cch : tt my nh th no ? khi ng nh th no ?

* Lnh : shutdown

S dng lnh : man shutdown xem thng tin v lnh ny

SYNTAXshutdown [options] when [message]

OPTIONS-c Cancel a shutdown that is in progress.

-f Reboot fast, by suppressing the normal call to fsckwhen rebooting.-h Halt the system when shutdown is complete.

-k Print the warning message, but suppress actual shutdown.

-n Perform shutdown without a call to init.

-r Reboot the system when shutdown is complete.

-t sec

V d :Tt ngay lp tc :shutdown -h now

Khi ng li ngay lp tc:shutdown -r nowTt my vo lc 8 ti (pm):shutdown -h 20:00

Sau 10 pht th tt my:shutdown -h +10

* Lnh : halt, reboot, poweroff

T kernel 2.74 tr v sau ny, lnh halt, reboot khng c gi trc tip m n c tch hp vo trong lnh shutdown nh bn thy trn. Nu bn dng cc kernel c th vn dng c cc lnh ny.

26-11-2007, 08:12 PM

lehoaiITBannedTham gia ngy: Oct 2007Ni c ng: C Mau Si GnBi gi: 968

Trnh son tho vn bn.

Trn windows c rt nhiu trnh son tho khc nhau nh office, wordpad, notepad... Trn *nix cng vy, nhng trnh son tho a thch c l l vi.

Trnh son tho ny c l l ph bin nht v thng dng nht trn cc h thng Unix cng tng t nh notepad ca windows.

truy nhp vi trong ca s terminal bn nh : vi

[root@duchai /]# vi

Trnh son tho s hin ra. Nh bn Fedora ti ang dng th n thay th vi bi VIM :

VIM son tho "thun tay hn" vi happy bn dng th m xem big grin

to 1 file mi bn nh : vi

[root@duchai /]# vi hello

Bn nhn phm "i" kch hot ch Insert, sau bn nh "Hello world!"

ghi li file bn bm phm "ESC" thot khi ch Insert. Sau nh ":wq! " lu li v thot ra khi vi.

"hello" [New] 1L, 14C written[root@duchai /]# more hellohello world ![root@duchai /]#LnhTChc nng

:rreadc / mfile

:wwriteGhi li file hin hnh

:qquitThot khivi

:wq!quit - writeGhi li file hin hnh, sau thot khivi.

:q!Thot khivim khng ghi li file hin hnh

Chi tit cc lnh ca vi c l phi thc hnh nhiu mt cht mi nh c.

Tham kho :

http://www.ss64.com/bash/vi.html

http://www.eng.hawaii.edu/Tutor/vi.html

VI Editor Commands

Switch to Text or Insert mode:

Open line above cursorOInsert text at beginning of lineIInsert text at cursoriInsert text after cursoraAppend text at line endA

Open line below cursoro

Switch to Command mode:Switch to command mode

Cursor Movement (command mode):

Scroll Backward 1 screenb

Scroll Up 1/2 screenuGo to beginning of line0Go to line nnGGo to end of line$

Scroll Down 1/2 screendGo to line number ##:##

Scroll Forward 1 screenf

Go to last lineGScroll by sentence f/b ( )Scroll by word f/b w b Move left, down, up, right h j k lLeft 6 chars6hDirectional Movement Arrow KeysGo to line #66G

Deleting text (command mode):Change wordcwReplace one characterrDelete worddwDelete text at cursorxDelete entire line (to buffer)dd

Delete current to end of lineDDelete 5 lines (to buffer)5dd

Delete lines 5-10:5,10d

Editing (command mode):Copy lineyyCopy n linesnyyCopy lines 1-2/paste after 3:1,2t 3Paste above current lineP

Paste below current linepMove lines 4-5/paste after 6:4,5m 6

Join previous lineJSearch backward for string?stringSearch forward for string/string Find next string occurrence n% (entire file) s (search and replace) /old text with new/ c (confirm) g (global - all):%s/oldstring/newstring/cgIgnore case during search:set icRepeat last command.Undo previous commanduUndo all changes to lineU

Save and Quit (command mode):Save changes to buffer:wSave changes and quit vi:wqSave file to new file:w file

Quit without saving:q!Save lines to new file:10,15w file

26-11-2007, 08:12 PM

lehoaiITBannedTham gia ngy: Oct 2007Ni c ng: C Mau Si GnBi gi: 968

Shells l g ?

Bn c th hiu nm na shell l 1 cch computer giao tip vi ngi dng hay ni cch khc l cch computer nhn lnh t ngi dng. Thn thng trn Linux dng "bash" shell.

Shell l gip ngi dng lm vic vi my tnh d dng hn vi nhng cu lnh "thn thin" mang tnh cht gi nh.

V d : cn copy tt c cc file trong th mc A vo th mc B cu lnh l : cp /A/* /B

* File '.bashrc'

Mi mt user khi c to ra s c 1 shell cho n nh ti ni phn trc, nh ngha shell cho user nm trong file .bashrc trong th mc /home/, v d y l /home/kikicoco

[root@duchai /]# cd /home/[root@duchai home]# cd kikicoco/[root@duchai kikicoco]# ls -altotal 56drwxr-xr-x 2 kikicoco kikicoco 4096 Nov 29 06:00 .drwxr-xr-x 4 root root 4096 Nov 28 14:49 ..-rw-r--r-- 1 kikicoco kikicoco 24 Nov 28 14:49 .bash_logout-rw-r--r-- 1 kikicoco kikicoco 191 Nov 28 14:49 .bash_profile-rw-r--r-- 1 kikicoco kikicoco 124 Nov 28 14:49 .bashrc-rw-r--r-- 1 kikicoco kikicoco 120 Nov 28 14:49 .gtkrc-rw------- 1 kikicoco kikicoco 35 Nov 29 06:00 .lesshst

[root@duchai kikicoco]# more .bashrc# .bashrc

# Source global definitionsif [ -f /etc/bashrc ]; then. /etc/bashrcfi

# User specific aliases and functions[root@duchai kikicoco]# more .bash_profile# .bash_profile

# Get the aliases and functionsif [ -f ~/.bashrc ]; then. ~/.bashrcfi

# User specific environment and startup programs

PATH=$PATH:$HOME/bin

export PATHunset USERNAME

Trong file .bashrc c ni n cc alias do ngi dng nh ngha. # User specific aliases and functions

Alias l g ?

alias thng thng c hiu l mt ci tn khc. Alias y cng gn nh th.

v d ti thm dng :

alias rm='rm -i'

Th iu ny c ngha l khi ti nh lnh rm trong terminal th lnh ny s c hiu l rm -i y chnh l alias ca rm.

V sao li cn n alias ?

trn trong lnh rm c tham s -i, i tc l interactive (prompt before any removal) c ngha l khi c tham xa -i th bt c file no b xa h iu hnh s hi xem ta c chc chn xa khng.

Nu dng tham s -f : force (ignore nonexistent files, never prompt) th h iu hnh s xa m khng cn hi. Khi bn mun xa nhanh th hy dng tham s ny.

Vic dng alias nhm mc ch to 1 "route" cho ngi dng. c bit i vi nhng my tnh quan trng nh my ch chng hn vic xa file cn phi ht sc thn trng, nu nh bn dng lnh sau : rm -R -f * m khng to alias nh trn s khin ton b s file trong th mc hin ti ca bn bin mt ngay lp tc --> mt di nh ci bm smile_confused

Bn c th to alias tm thi bng cch dng lnh alias hoc xa 1 alias bng lnh unalias:

SYNTAXalias [-p] [name[=value] ...]

unalias [-a] [name ... ]

26-11-2007, 08:13 PM

lehoaiITBannedTham gia ngy: Oct 2007Ni c ng: C Mau Si GnBi gi: 968

Cc lnh thng dng trn h thng Unix

Ti ch a ra cc lnh km chc nng, cc tham s ca n th bn cn xem thm.

1. Lnh man, info v apropos : thng tin v lnh2. Lnh cd : chuyn th mc3. Lnh ls : lit k file thng thng hay dng ls -al hoc ls -l4. Lnh file : xem thng tin loi file ca 1 file file 5. Lnh more v less : xem ni dung file more 6. Lnh cat v tail : xem ni dung file cat 7. Lnh cp : lnh copy8. Lnh mv : lnh di chuyn hoc i tn file, th mc9. Lnh mkdir : to th mc mi10. Lnh rm v rmdir : xa file v xa th mc rng11. Lnh dir : bng vi ls -l12. Lnh pwd : xem v tr th mc hin thi13. Lnh date : xem ngy14. Lnh cal : xem lich, v d cal 200615. Lnh exit : thot khi terminal

Cn sau y l mt s lnh yu thch :

1. Lnh touch : to file2. Lnh find : tm kim (s c 1 bi vit ring v lnh ny)3. Lnh grep : tm kim ni dung file h tr regular expression4. Lnh who, whoami, whatis, whereis, which : ng nh ngha ca cc t ny5. Lnh echo : hin th ni dung 1 bin ,...

Cc lnh dnh cho qun tr h thng :

1. Lnh last : hin th cc user login gn y2. Lnh df : xem thng tin a, thng thng hay dng df -h3. Lnh du : xem thng tin dung lng file, th mc4. Lnh top : ci ging nh taskmanager ca windows, n s hin th thng tin v cc processes5. Lnh free : xem tnh hnh b nh6. Lnh ps : xem thng tin processes7. Lnh kill : tt process8. Lnh mount v unmount :9. Lnh chmod : thay i permissions i vi file10. Lnh chown : thay i ngi s hu i vi file11. Lnh chgrp : thay i group i vi file12. Lnh chroot

Ngoi cc lnh trn cn c rt nhiu lnh khc, c th tham kho ti y :

http://www.ss64.com/bash/

Backup sao lu gi liu vi UNIX

Cc lnh cn dng : tar, gzip, gunzip

V d vi tar :

tar -czvf MyArchive Source_filehoctar --create --gzip --verbose --file=MyArchive Source_file

tar -xzvf MyArchive Source_filehoctar --extract --gunzip --verbose --file=MyArchive Source_file

gzip l mt phn ca tar, tuy nhin gzip v gunzip vn dng c c lp.

Vic backup v sao lu nn vit thnh cc job h thng t ng lm.

V d ti cn backup d liu ca mysql hng tun vo Ch nht.

#!/bin/bashDate=`date '+%a'`Day=`date '+%m%d'`if [ $Date == 'Sun' ]thencd /mysqldatafor ix in *doif [ -d $ix ]thentar -czvf /kikicoco/backup/database_$Day.$ix.tar $ixfidonefi

on script bn cho vo 1 file, v d : db_backup.sh

Sau chmod +x cho file db_backup.sh c ngha l cho file ny c quyn chy sau to schedule cho file ny.

Ci ny n tng t nh schedule task ca windows.

to schedule trn Linux bn dng crontab.

[root@duchai etc]# ls -l| grep cron-rw-r--r-- 1 root root 329 Feb 11 2006 anacrontabdrwxr-xr-x 2 root root 4096 Feb 16 2006 cron.ddrwxr-xr-x 2 root root 4096 Aug 3 13:43 cron.daily-rw-r--r-- 1 root root 0 Aug 3 13:21 cron.denydrwxr-xr-x 2 root root 4096 Dec 11 2005 cron.hourlydrwxr-xr-x 2 root root 4096 Aug 3 13:18 cron.monthly-rw-r--r-- 1 root root 255 Dec 11 2005 crontabdrwxr-xr-x 2 root root 4096 Aug 3 13:21 cron.weekly[root@duchai etc]# more crontabSHELL=/bin/bashPATH=/sbin:/bin:/usr/sbin:/usr/binMAILTO=rootHOME=/# run-parts01 * * * * root run-parts /etc/cron.hourly02 4 * * * root run-parts /etc/cron.daily22 4 * * 0 root run-parts /etc/cron.weekly42 4 1 * * root run-parts /etc/cron.monthly

Cc job ny s c t trong cc file trn hoc trong th mc : /var/spool/cron/crontabs

S dng crontab - l bit cc jobs ca user hin ti. Nu cha c dng lnh crontab -e to jobs.

C php 1 dng trong crontab :

Minute(0-59) Hour (0-23) Day of Month (1-31) Month (1-12 or Jan-Dec) Day of Week (0-6 or Sun-Sat) Command

0 2 12 * 0,6 /usr/bin/find

Tham kho : Cron and Crontab usage and examples.

Ci t v cp nht phn mm trong Linux

Trn windows cc file ci t c nh dng .exe, .msi, .vis,... vic ci t rt d dng bng vic chy cc file ny. Trn unix cng tng t nh th. Tuy nhin trong cc bi vit ny ti ch dng terminal, khng dng ch giao din.

Vy vic ci t trn trn linux nh th no ?

* RPM : Red Hat Package Manager

Cc chng trnh s c ui .rpm, c php nh sau :

rpm -i new_program.rpm--> ci t chng trnh mi (-i l vit tt ca install)

rpm -q program_name --> kim tra xem 1 chng trnh c ci hay cha ?

V d vi Fedora 5/6:

[root@duchai sysconfig]# rpm -q mysqlmysql-5.0.18-2.1[root@duchai sysconfig]# rpm -q firefoxfirefox-1.5.0.1-9

By gi cn nng cp nn Firefox 2.0

Tham kho :http://fedoraproject.org/wiki/Firefox2

Chy lnh :

yum -y install firefox

Cc lnh c bn vi yum:

Ci t : yum -y install G b : yum -y remove Xem cc gi ci : yum list

V d : xem cc gi ci ca php :

[root@web ~]# yum list php*Loading "installonlyn" pluginSetting up repositoriescore 100% |=========================| 1.1 kB 00:00updates 100% |=========================| 1.2 kB 00:00extras 100% |=========================| 1.1 kB 00:00Reading repository metadata in from local filesprimary.xml.gz 100% |=========================| 306 kB 00:01################################################## 1072/1072Installed Packagesphp.i386 5.1.6-3.1.fc6 installedphp-Smarty.noarch 2.6.13-1.fc6 installedphp-bcmath.i386 5.1.6-3.1.fc6 installedphp-cli.i386 5.1.6-3.1.fc6 installedphp-common.i386 5.1.6-3.1.fc6 installedphp-gd.i386 5.1.6-3.1.fc6 installedphp-mbstring.i386 5.1.6-3.1.fc6 installed

Chi tit cc lnh vi yum : yum -h

Khi ht swap th ta cn thm swap file, v d cn thm 1G swap :

/usr/sbin/mkfile 1024m /swapfile --> to swap file/usr/sbin/swap -a /swapfile --> cho h thng bit swap file mi nm u

n v tnh : kilobytes (k), blocks (b), or megabytes (m)

Kim tra swap file mi c thm hay cha ?

swap -l

(Su tm t nhiu ngun)

thay i ni dung bi:lehoaiIT, 14-01-2008 lc11:40 AM

Cc lnh linux dnh cho ngi qun tr server !1. Hin th tin trnh trong h thng Linux# ps aux | less

Ngoi ra lnh ny c th s dng kt hp vi mt s tham s khc nh:# ps A: Kim tra mi tin trnh trong h thng.# ps -U root -u root N: Kim tra mi tin trnh ngoi tr nhng tin trnh h thng.# ps -u username: Kim tra nhng tin trnh c thc hin bi mt ngi dng nht nh.Hoc bn c th s dng lnh # top xem nhng tin trnh ang chy trn h thng trong thi gian thc.2. Kim tra thng tin Socket v thng tin mng TCP/UDP Mi Socket TCP.

Mi Socket UDP.

Mi kt ni ssh/ftp/http/https.

Mi tin trnh cc b c kt ni ti my ch X.

Mi Socket TCP trong trng thi FIN-WAIT-1.Di y l mt s lnh ss:# ss s: Hin th tng s Socket.# ss -1: Hin th mi cng m.# ss pl: Kim tra tn tin trnh s dng Socket m s dng lnh sau:# ss -lp | grep: Kim tra ngi dng ang lm vic vi Socket m.# ss -t a: Hin th mi Socket TCP.# ss -u a: Hin th mi Socket UDP.3. Theo di Average CPU Load v Disk Activity ly thng tin th mc NFS bn hy s dng lnh sau:# iostat n6. Kim tra ngi dng ng nhp:# w username7. Kim sot hnh vi h thng, phn cng v thng tin h thng trong Linux: # vmstat 3 # , vmstat m, # vmstat a8. Kim tra thng tin phn cng ca h thng Linuxdi quyn root user v s dng lnh sau:# hdparm -I /dev/sdaHoc dng lnh:$ sudo hdparm -I /dev/sda kim tra thng s trn hosting cng nh server ci h iu hnh Linux, cc bn c th dng mt s lnh sau:

# cat /proc/cpuinfo : hin th thng tin CPU# cat /proc/meminfo : hin th thng tin v RAM ang s dng# cat/ proc/version : hin th phin bn ca kernel# free -m : hin th lng RAM cn trng# df -h : hin th thng tin nhng file h thng ni mi file thng tr hoc tt c nhng file mc dnh v lnh ny c th xem c dung lng cng s dng v cn trng bao nhiu.# du -sh : xem dung lng ca th mc# du : xem chi tit dung lng ca cc th mc bn trong n.# du -sh * : xem dung lng chi tit ca tt c cc file trong th mc hin hnh.

Linux Administrator v Webmaster.

Cc lnh sau c thc nghim vi Linux CentOS 5.

1. Cc lnh c bn# ls // ging nh dir ca windows# vi // m trnh son tho vn bn text# passwd // i password user hin ti# chmod // cp quyn cho th mc v tp tin (chmod 777) l ton quy# chgrp // thay i group cho th mc v tp tin# chown // thay i owner th mc v tp tin# cp a b // copy file a vo th mc b# reboot // khi ng li h thng# shutdown -h now // shutdown h thng (tt my)

2. Networking (hn ch s dng khi ang ch remote):

# ifconfig // xem v config ip ca server# setup // chn Network Configuration set IP cho server# vi /etc/resolv.conf // cu hnh dns cho server# ifdown eht0 // down card mng eth0# ifup eht0 // up card mng eth0# service network restart // khi ng li service mng

3. Kim tra h thng

# top // xem tnh trng s dng ti nguyn RAM, CPU ca h thng# uptime // xem tnh trng trung bnh ca h thng v thi gian h thng online# fdisk -l // xem cc cng HDD c trn server# df -h // kim tra mc s dng cng HDD# cat /proc/cpuinfo // kim tra CPU# cat /proc/meminfo // kim tra mc s dng b nh# du -hs // kim tra dung lng th mc

4. Webserver v MySQL

# service httpd status // xem tnh trng webserver# service httpd restart // khi ng li webserver# service mysqld restart // khi ng li mysql# mysqlcheck -Aao -auto-repair -u[MySqlAdmin] -p[Password] // kim tra sa v optimize mysql database

5. Nn v gii nn

# tar -cvzpf archive.tgz /home/example/public_html/folder // nn mt th mc# tar -tzf backup.tar.gz // lit k file nn gz# tar -xvf archive.tar // gii nn mt file tar

Hng dn mount cng Backup

Intro ny phi lm tht cn thn v ch l ko dng lnh fdisk /dev/sda hay fdisk /dev/hda v bn s edit main v boot partition

Chy lnh fdisk xem nhng cng ang hin hu trn serverCode:fdisk -l

Disk /dev/hda: 80.0 GB, 80000000000 bytes255 heads, 63 sectors/track, 9726 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesDevice Boot Start End Blocks Id System/dev/hda1 * 1 13 104391 83 Linux/dev/hda2 14 268 2048287+ 82 Linux swap/dev/hda3 269 9726 75971385 83 LinuxDisk /dev/hdc: 80.0 GB, 80000000000 bytes255 heads, 63 sectors/track, 9726 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesChng ta thy 1 cng l hda v 1 cng l hdc. hda l main boot drive. chng ta cn format cng cn li.Code:fdisk /dev/hdc

-press n for new partion-press p for primary partition-press 1 for the first partition-press enter for the first AND last cylinders. This will make it automatically use the entire disk-press w for write out to save what you have doneCode:mkfs.ext3 /dev/hdc1By gi ta mount cng ny vo backup

Code:mkdir /backup

Code:pico -w /etc/fstab

Chn thm dng bn diCode:/dev/hdc1 /backup ext3 defaults 1 1

Code:mount /backupTi tp tin bng lnh wget trong linuxng vo ngy 11 Thang T 2011 lc 16:03 biDuy KhnhMc:IT,Unix/Linux||Tags:linuxBnh lun (0)1. Ti sao dngwget?Trong mi trng UNIX/Linux, chng ta c th di chuyn ti cc th mc mt cch nhanh chng bng lnhcd(change directory) trongca s lnh Terminal. Nu mt lc no chng ta mun ly mt tp tin t Internet v v lu th mc hin hnh th s mt nhiu thi gian hn khi nh phi s dng trnh duyt web ti tp tin v la chn th mc cha tp tin y. Vi cng cwgetsn c trong UNIX/Linux, chng ta c th ti trc tip tp tin v th mc hin hnh.2. Dngwgetnh th no?Cu trc lnh c bn cawgetch ngn gn nh sau:wgethttp://a-ch-trang-web/tp-tinChng hn nh chng ta mun ti mt tp tin MP3 vo th mc dnh ring cho MP3 (/media/Data/Audio/Music/), chng ta ch cn 2 cu lnh sau:cd /media/Data/Audio/Musicwgethttp://a-ch-trang-web/tp-tin.mp3Trong trng hp mun xem qua m HTML ca mt trang web hoc ni dung mt tp tin vn bn dng text, chng ta cng c th dngwgetthay v m a ch trnh duyt:wget -q -O -http://a-ch-trang-web/tp-tin3. Dngwgetqua proxyTrong mt s trng hp, chng ta khng th ti trc tip d liu t mt trang web, m cn phi truy cp qua mt proxy trung gian. Chng ta c th ci t thng s proxy cho trnh duyt web, nhng vic s lm chng ta mt nhiu thi gian nu nh ch ti 1 tp tin t 1 trang web no ri li g b cc thng s proxy khi trnh duyt.Ch bng 1 cu lnh n gin trong ca s lnh Terminal, chng ta c th dngwgetmt cch bnh thng. Cu lnh ny gip chng ta truy cp cc a ch web qua proxy:export HTTP_PROXY="http://a-ch-proxy:cng-proxy/"Khi cu lnhwgetc th c s dng bnh thng nh trc. Trong trng hp bn cn ti tp tin t mt a ch qua giao thc FTP th bn cn thm bin FTP_PROXY theo cch tng t:export FTP_PROXY="http://a-ch-proxy:cng-proxy/"Bn lu l mc d thit lp ch s dng proxy cho giao thc FTP nhng giao thc ca a ch proxy vn phi l http.Sau khi ti tp tin bngwgetxong, nu bn mun xa b ch s dng proxy th dng cu lnh:env -u HTTP_PROXYv/hocenv -u FTP_PROXYhay ch n gin l khi ng li my tnh, v bin mi trng to bi lnhexportkhng c lu tr vnh vin, m cn c khi to li nu cn, mi khi my tnh c khi ng li.