50 Most Frequently Used UNIX / Linux Commands (With Examples)(1)
2014-05-13 12:09
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This article provides practical examples for 50 most frequently used commands in Linux / UNIX.This is not a comprehensive list by any means, but this should give you a jumpstart on some of the common Linux commands. Bookmark this article for your future reference.
Did I miss any frequently used Linux commands?Leave a commentand let me know.
本文出自 “小小鸟你妈” 博客,请务必保留此出处http://xiaoxiaoniao.blog.51cto.com/8727225/1410389
Did I miss any frequently used Linux commands?Leave a commentand let me know.
1. tar command examples
Create a new tar archive.$ tar cvf archive_name.tar dirname/Extract from an existing tar archive.
$ tar xvf archive_name.tarView an existing tar archive.
$ tar tvf archive_name.tarMore tar examples:The Ultimate Tar Command Tutorial with 10 Practical Examples
2. grep command examples
Search for a given string in a file (case in-sensitive search).$ grep -i "the" demo_filePrint the matched line, along with the 3 lines after it.
$ grep -A 3 -i "example" demo_textSearch for a given string in all files recursively
$ grep -r "ramesh" *More grep examples:Get a Grip on the Grep! – 15 Practical Grep Command Examples
3. find command examples
Find files using file-name ( case in-sensitve find)# find -iname "MyCProgram.c"Execute commands on files found by the find command
$ find -iname "MyCProgram.c" -exec md5sum {} \;Find all empty files in home directory
# find ~ -emptyMore find examples:Mommy, I found it! — 15 Practical Linux Find Command Examples
4. ssh command examples
Login to remote hostssh -l jsmith remotehost.example.comDebug ssh client
ssh -v -l jsmith remotehost.example.comDisplay ssh client version
$ ssh -V OpenSSH_3.9p1, OpenSSL 0.9.7a Feb 19 2003More ssh examples:5 Basic Linux SSH Client Commands
5. sed command examples
When you copy a DOS file to Unix, you could find \r\n in the end of each line. This example converts the DOS file format to Unix file format using sed command.$sed 's/.$//' filenamePrint file content in reverse order
$ sed -n '1!G;h;$p' thegeekstuff.txtAdd line number for all non-empty-lines in a file
$ sed '/./=' thegeekstuff.txt | sed 'N; s/\n/ /'More sed examples:Advanced Sed Substitution Examples
6. awk command examples
Remove duplicate lines using awk$ awk '!($0 in array) { array[$0]; print }' tempPrint all lines from /etc/passwd that has the same uid and gid
$awk -F ':' '$3==$4' passwd.txtPrint only specific field from a file.
$ awk '{print $2,$5;}' employee.txtMore awk examples:8 Powerful Awk Built-in Variables – FS, OFS, RS, ORS, NR, NF, FILENAME, FNR
7. vim command examples
Go to the 143rd line of file$ vim +143 filename.txtGo to the first match of the specified
$ vim +/search-term filename.txtOpen the file in read only mode.
$ vim -R /etc/passwdMore vim examples:How To Record and Play in Vim Editor
8. diff command examples
Ignore white space while comparing.# diff -w name_list.txt name_list_new.txt 2c2,3 < John Doe --- > John M Doe > Jason BourneMore diff examples:Top 4 File Difference Tools on UNIX / Linux – Diff, Colordiff, Wdiff, Vimdiff
9. sort command examples
Sort a file in ascending order$ sort names.txtSort a file in descending order
$ sort -r names.txtSort passwd file by 3rd field.
$ sort -t: -k 3n /etc/passwd | more
10. export command examples
To view oracle related environment variables.$ export | grep ORACLE declare -x ORACLE_BASE="/u01/app/oracle" declare -x ORACLE_HOME="/u01/app/oracle/product/10.2.0" declare -x ORACLE_SID="med" declare -x ORACLE_TERM="xterm"To export an environment variable:
$ export ORACLE_HOME=/u01/app/oracle/product/10.2.0
11. xargs command examples
Copy all images to external hard-drive# ls *.jpg | xargs -n1 -i cp {} /external-hard-drive/directorySearch all jpg images in the system and archive it.
# find / -name *.jpg -type f -print | xargs tar -cvzf images.tar.gzDownload all the URLs mentioned in the url-list.txt file
# cat url-list.txt | xargs wget –c
12. ls command examples
Display filesize in human readable format (e.g. KB, MB etc.,)$ ls -lh -rw-r----- 1 ramesh team-dev 8.9M Jun 12 15:27 arch-linux.txt.gzOrder Files Based on Last Modified Time (In Reverse Order) Using ls -ltr
$ ls -ltrVisual Classification of Files With Special Characters Using ls -F
$ ls -FMore ls examples:Unix LS Command: 15 Practical Examples
13. pwd command
pwd is Print working directory. What else can be said about the good old pwd who has been printing the current directory name for ages.14. cd command examples
Use “cd -” to toggle between the last two directoriesUse “shopt -s cdspell” to automatically correct mistyped directory names on cdMore cd examples:6 Awesome Linux cd command Hacks15. gzip command examples
To create a *.gz compressed file:$ gzip test.txtTo uncompress a *.gz file:
$ gzip -d test.txt.gzDisplay compression ratio of the compressed file using gzip -l
$ gzip -l *.gz compressed uncompressed ratio uncompressed_name 23709 97975 75.8% asp-patch-rpms.txt
16. bzip2 command examples
To create a *.bz2 compressed file:$ bzip2 test.txtTo uncompress a *.bz2 file:
bzip2 -d test.txt.bz2More bzip2 examples:BZ is Eazy! bzip2, bzgrep, bzcmp, bzdiff, bzcat, bzless, bzmore examples
17. unzip command examples
To extract a *.zip compressed file:$ unzip test.zipView the contents of *.zip file (Without unzipping it):
$ unzip -l jasper.zip Archive: jasper.zip Length Date Time Name -------- ---- ---- ---- 40995 11-30-98 23:50 META-INF/MANIFEST.MF 32169 08-25-98 21:07 classes_ 15964 08-25-98 21:07 classes_names 10542 08-25-98 21:07 classes_ncomp
18. shutdown command examples
Shutdown the system and turn the power off immediately.# shutdown -h nowShutdown the system after 10 minutes.
# shutdown -h +10Reboot the system using shutdown command.
# shutdown -r nowForce the filesystem check during reboot.
# shutdown -Fr now
19. ftp command examples
Both ftp and secure ftp (sftp) has similar commands. To connect to a remote server and download multiple files, do the following.$ ftp IP/hostname ftp> mget *.htmlTo view the file names located on the remote server before downloading, mls ftp command as shown below.
ftp> mls *.html - /ftptest/features.html /ftptest/index.html /ftptest/othertools.html /ftptest/samplereport.html /ftptest/usage.htmlMore ftp examples:FTP and SFTP Beginners Guide with 10 Examples
20. crontab command examples
View crontab entry for a specific user# crontab -u john -lSchedule a cron job every 10 minutes.
*/10 * * * * /home/ramesh/check-disk-spaceMore crontab examples:Linux Crontab: 15 Awesome Cron Job Examples
21. service command examples
Service command is used to run the system V init scripts. i.e Instead of calling the scripts located in the /etc/init.d/ directory with their full path, you can use the service command.Check the status of a service:# service ssh statusCheck the status of all the services.
service --status-allRestart a service.
# service ssh restart
22. ps command examples
ps command is used to display information about the processes that are running in the system.While there are lot of arguments that could be passed to a ps command, following are some of the common ones.To view current running processes.$ ps -ef | moreTo view current running processes in a tree structure. H option stands for process hierarchy.
$ ps -efH | more
23. free command examples
This command is used to display the free, used, swap memory available in the system.Typical free command output. The output is displayed in bytes.$ free total used free shared buffers cached Mem: 3566408 1580220 1986188 0 203988 902960 -/+ buffers/cache: 473272 3093136 Swap: 4000176 0 4000176If you want to quickly check how many GB of RAM your system has use the -g option. -b option displays in bytes, -k in kilo bytes, -m in mega bytes.
$ free -g total used free shared buffers cached Mem: 3 1 1 0 0 0 -/+ buffers/cache: 0 2 Swap: 3 0 3If you want to see a total memory ( including the swap), use the -t switch, which will display a total line as shown below.
ramesh@ramesh-laptop:~$ free -t total used free shared buffers cached Mem: 3566408 1592148 1974260 0 204260 912556 -/+ buffers/cache: 475332 3091076 Swap: 4000176 0 4000176 Total: 7566584 1592148 5974436
24. top command examples
top command displays the top processes in the system ( by default sorted by cpu usage ). To sort top output by any column, Press O (upper-case O) , which will display all the possible columns that you can sort by as shown below.Current Sort Field: P for window 1:Def Select sort field via field letter, type any other key to return a: PID = Process Id v: nDRT = Dirty Pages count d: UID = User Id y: WCHAN = Sleeping in Function e: USER = User Name z: Flags = Task Flags ........To displays only the processes that belong to a particular user use -u option. The following will show only the top processes that belongs to oracle user.
$ top -u oracleMore top examples:Can You Top This? 15 Practical Linux Top Command Examples
本文出自 “小小鸟你妈” 博客,请务必保留此出处http://xiaoxiaoniao.blog.51cto.com/8727225/1410389
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