Basic Shell Commands

For detailed information on UNIX commands type “man command” where “command” is the command name you are looking for more info on.

Command Description
apropos Searches the man pages for a keyword you specify. The name of the man page is in the first column.> apropos floppy
eject eject (1) – eject media such as CD-ROM and floppy from drive
fd fd (7d) – drivers for floppy disks and floppy disk controllers

cat  This command will display the contents of a file.> cat filename

cd Use cd to Change Directories. NOTE: If directoryname is not in the current directory you must include the path.> cd directoryname> cd path/directoryname

chgrp  CHanges the GRouP a file belongs to.> chgrp groupname filename

 chmod  This command allows either the owner of the file or the owner of the directory to CHange MODes (file permissions).> chmod go+rx filename


  • u ~ user’s permissions
  • g ~ group’s permissions
  • o ~ other’s permissions
  • a ~ all permissions (user, group, and other)
  • + ~ add permissions
  • – ~ remove permissions
 clear  This command clears the screen.> clear

 cp  Use cp to CoPy files.> cp source_filename target_filename

 diff  This command can be used to look for DIFFerences between two files.> diff fileA fileB

 exit  If you initialize a new shell with a command like csh you can use the built-in shell function exit to quit the new shell.> exit

 find  This command will recursively descend the directory you specify to locate files.> find directory -name filename -print

 grep  Use this command to search a file or standard out for a pattern (string) you specify.> grep pattern filename

 groups  Use this command to show the groups a user belongs to.> groups username

 gunzip  Use this command to uncompress a zipped file (zipped files have a .gz suffix).> gunzip filename.gz

 gzip  Use this command to compress (zip) a file (when a file is zipped the .gz suffix is added automatically).> gzip filename

 kill  Use this command to terminate runaway processes that you own (type the command ps to find your active processes and their PIDs – process identity numbers).> kill -9 PID#

 ln  Use this command to create a LiNk, which allows a file to be accessed by a different name. Links may be removed with the rm command.> ln sourcefile linkname

 logout  Use this built-in shell function to logout of your current login shell.> logout

 lpq  Shows the print queue of the printer you specify.> lpq -Pprintername

 lpr  Use this command to print a file.> lpr -Pprintername filename

 lprm  This command is used to remove a job from the print queue (use lpq to find the job number).> lprm -Pprintername job# Printer printername@speedracer: checking perms ‘username@hostname+job#‘ dequeued ‘username@hostname+job#

 ls  This command ListS the contents of the directory. Add the -l option to view the “Long format,” which shows the mode (permissions), number of links, owner, group, size in bytes, time of last modification, and file or directory name.> ls -l total 12 drwxr-xr-x 2 user group 512 Oct 23 2000 Directoryname1 -rw——- 1 user group 1802 Dec 20 1999 Filename1 drw——- 7 user group 1024 May 15 11:40 directoryname2 -rw——- 1 user group 64 Mar 5 12:20 filename2

 man  Use the man command to view the complete MANual page or “man page” that you select by name.> man ls Reformatting page. Wait…

 mkdir  Use this command to MaKe a DIRectory.> mkdir directoryname

 more  Displays the contents of a file or standard out one page at a time. Press ‹Space› to go to the next page.> more filename> ls | more Directoryname1 Filename1 directoryname2 filename2 ⋮ –More–

 mv Use this command to rename or MoVe a file to another directory.> mv source_filename target_filename

 ps  Shows information about processes. You can use the command shown below to see the full listing of every processes you have running, or just type ps to see the short listing of your active processes.> ps -ef | grep username

 pwd  This command shows the full path of your Present Working Directory.> pwd /u/username/directoryname

 rm  ReMove files from a directory. You will not be able to recover a file that has been deleted!> rm filename

 rmdir  ReMove an empty DIRectory. You will not be able to recover a directory that has been deleted!> rmdir directoryname

 source  Reads commands from a file. For example, if you make changes to your .bashrc file and you don’t want to logout and then log back in for the changes to take effect, just source the file:> source ~/.bashrc

 ssh  This program is a Secure SHell client. Use ssh to login to remote computers.> ssh

 tar  Use this command to archive files or directories. This example will archive the directory directory_to_tar and all of it’s files and subdirectories to an archive called new_archive.tar :> tar cvf new_archive.tar directory_to_tar

This example will extract all of the files (and directories) from the archive named tarfile.tar into the directory called target_directory :> tar xvf tarfile.tar target_directory

 touch  Use this command to set the access and modification times of a file, or if the file named doesn’t exist, touch will create an new, empty file.> touch filename

 which  This built-in shell function shows you where a command or binary (executable), is located (i.e. “WHICH one” you are using).> which netscape /usr/local/bin/X11/netscape