UNIX Commands

Commands for the UNIX operating system are case sensitive. UNIX commands are typically lower case. There can be up to three parts for each command i.e. command [options] arguments. Below are some common UNIX commands with descriptions and examples.

of UNIX Command
of UNIX Command
File Commands
cat Concatenates a file. cat filename
cp Copy a file. cp oldfilename newfilename
chgrp Change root of directory or file. chgrp root filename
chown Change ownership of director or file. chown admin filename
chmod Set permissions on directory or file. chmod 755 filename
date Displays current day, date and time. date
diff Displays the difference between two text files. diff filename1 filename2
file Display file type. file filename
less Displays the file with minimal space. less filename
mail Read and send email messages. mail
more Displays the contents of a file with page breaks. more filename
mv Rename a file or directory or move a file to another directory. mv oldfilename newfilename
mv /etc/filename /usr/filename
pico A basic text editor. pico
pico filename
pine Read and send email messages. Has more features than mail. pine
ps Reports the status of the currently running processes. ps
ps options
pwd Displays current directory path. pwd
quota -v Displays current disk usage and limits. quota -v
rm Remove (delete) a file. rm filename
sort Sort the lines of a text file alphabetically. sort filename
vi Text editor. vi
vi filename
w Indicates who is currently logged in with more information than "who." w
wc Counts the number of lines wc filenames
who Indicates who is currently logged in. who
./ Execute a program from the command line. ./filename
* Wildcard. rm abc*.pl
(This will delete all files starting with abc and ending with .pl)

Directory Commands
pwd Displays current directory path. pwd
echo $cwd Displays the logical path or directory. echo $cwd
cd Change directory. cd /usr/
cd .. Go back one directory level. cd ..
ls Lists the contents of the current directory. ls -a
mkdir Make a directory. mkdir directory-name
rmdir Remove a directory. rmdir directory-name

General Commands
passwd Allows you to change your password. passwd
logout Ends your current session. logout
ps Displays current processes. ps
clear Clears the terminal screen. clear
quota -v Display disk usage. quota -v
gzip Compresses a file. gzip filename
gunzip Uncompresses a file. gunzip filename

Help Commands
apropos Commands for a specific topic. apropos mail
help A list of online help topics or help on a specific topic. help
help mail
man A list of manuals or a manual on a specific command. man
man mail
whatis A description of a specific command. whatis mail

Print Commands
lpr Prints a postscript file. lpr filename
enscript Prints text files to a postscript printer. enscript -Pprintername filename
printers Displays a list of printers and locations. printers
lpq Prints the current print queue. lpq -Pprintername
lprm Removes a print job from queue. lprm -Pprintername queuenumber