UNIX commands

Definition of UNIX commands in The Network Encyclopedia.

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What is UNIX commands?

Commands for administering various aspects of the UNIX operating system. Most of these commands can be used in batch files to perform complex administrative tasks from a single command. You can create batch files with a text editor such as ed or vi and schedule their execution by using the cron command. The following table describes some commonly used UNIX commands. (They are listed in alphabetical order, not according to function.)

Some commands have a simple syntax, such as the cd command for changing the current directory. Others are more complex and include scripting engines and even programming compilers, such as cc, the UNIX C compiler.

Most versions of UNIX support these commands, but there are subtle differences from system to system. To see the syntax for any UNIX command, use the man command, which provides access to the UNIX online command reference on most UNIX systems. For example, to see the syntax for the cd command, type man cd.

Common UNIX Commands

Command Description
alias
Displays or sets aliases for long command strings
awk
Searches a file for a pattern and performs an action on the lines containing that pattern
bg
Moves a stopped process into the background and restarts it
cal
Displays a calendar
cat
Concatenates or displays files
cc
C language compiler
cd
Changes the current directory
chgrp
Changes group ownership of a file
chmod
Changes access permissions for a file
chown
Changes individual ownership of a file
chsh
Changes the default shell in a password file
clear
Clears the screen
cmp
Compares two files and returns the line numbers that differ
cp
Copies a file
csh
C shell command interpreter
date
Displays the date and time
df
Displays the amount of free disk space in a file system
diff
Displays differences between two files
du
Displays file system usage
echo
Echoes the text typed following the command to the screen; in a batch file, displays a line on the screen
ed
Text editor
elm
Text-based e-mail
emacs
Text editor
f77
FORTRAN77 compiler
fg
Moves a stopped process to the foreground and restarts it
find
Finds a file with specified characteristics
ftp
File Transfer Protocol (FTP) client
grep
Searches a file for a text pattern
head
Displays the beginning of a file (by default, displays the first 10 lines)
help
Displays help
hostname
Displays the name of the current host system
kill
Ends a running process
ksh
Korn shell command interpreter
ln
Links files
lpq
Displays the print queue
lpr
Sends a print job to the spooler
ls
Lists files in a directory and displays the file statistics
mail
Sends e-mail
man
Accesses the online manual
mkdir
Creates a new directory
more
Displays a file one screen at a time
mv
Moves or renames a file
passwd
Changes your password
pico
Text editor
pine
Text-based e-mail program
ps
Displays the status of a process
pwd
Displays the name of the current directory
rm
Deletes a file
rmdir
Deletes a directory
sed
Stream line editor
sh
Bourne shell command interpreter
sleep
Pauses a process
sort
Sorts or merges files
split
Splits a file into multiple files
talk
Text-based chat
telnet
Terminal emulator
uucp
UNIX-to-UNIX system file copies
uudecode
Decodes a uuencoded file
uuencode
Encodes a binary file
vi
Text editor
who
Displays who else is logged on
whoami
Displays the name of the user currently logged on
whois
Finds remote users and sites
write
Sends a message to a user

See also