Unix / Linux commands

Brief overview of Unix / Linux commands

Below is a listing of each of the Unix / Linux commands currently listed on Computer Hope and a brief explanation of what each of the commands do. This is a full listing which means not all the below commands will work with your distribution and may also not work because of your privileges. Clicking on any of the commands will display additional help and information about that command.

Command	Description
a2p	Creates a Perl script from an awk script.
ac	Prints statistics about users' connect time.
alias	Create a name for another command or long command string.
ar	Maintain portable archive or library.
arch	Display the architecture of the current host.
arp	Manipulate the system ARP cache.
as	An assembler.
at	Command scheduler.
awk	Awk script processing program.
basename	Deletes any specified prefix from a string.
bash	Command Bourne interpreter
bc	Calculator.
bdiff	Compare large files.
bfs	Editor for large files.
bg	Continues a program running in the background.
biff	Enable / disable incoming mail notifications.
break	Break out of while, for, foreach, or until loop.
bs	Battleship game.
bye	Alias often used for the exit command.
cal	Calendar
calendar	Display appointments and reminders.
cancel	Cancels a print job.
cat	View or modify a file.
cc	C compiler.
cd	Change directory.
chdir	Change directory.
checkeq	Language processors to assist in describing equations.
checknr	Check nroff and troff files for any errors.
chfn	Modify your own information or if super user or root modify another users information.
chgrp	Change a groups access to a file or directory.
chkey	Change the secure RPC key pair.
chmod	Change the permission of a file.
chown	Change the ownership of a file.
chsh	Change login shell.
cksum	Display and calculate a CRC for files.
clear	Clears screen.
cls	Alias often used to clear a screen.
cmp	Compare files.
col	Reverse line-feeds filter.
comm	Compare files and select or reject lines that are common.
compress	Compress files on a computer.
continue	Break out of while, for, foreach, or until loop.
copy	Copy files.
cp	Copy files.
cpio	Creates archived CPIO files.
crontab	Create and list files that you wish to run on a regular schedule.
csh	Execute the C shell command interpreter
csplit	Split files based on context.
ctags	Create a tag file for use with ex and vi.
cu	Calls or connects to another Unix system, terminal or non-Unix system.
curl	Transfer a URL.
cut	Cut out selected fields of each line of a file.
date	Tells you the date and time in Unix.
dc	An arbitrary precision arithmetic package.
dd	Convert and copy a file.
df	Display the available disk space for each mount.
deroff	Removes nroff/troff, tbl, and eqn constructs.
dhclient	Dynamic Host Configuration Protocol Client.
diff	Displays two files and prints the lines that are different.
dig	DNS lookup utility.
dircmp	Lists the different files when comparing directories.
dirname	Deliver portions of path names.
dmesg	Print or control the kernel ring buffer.
dos2unix	Converts text files between DOS and Unix formats.
dpost	Translates files created by troff into PostScript.
du	Tells you how much space a file occupies.
echo	Displays text after echo to the terminal.
ed	Line oriented file editor.
edit	Text editor.
egrep	Search a file for a pattern using full regular expressions.
elm	Program command used to send and receive e-mail.
emacs	Text editor.
enable	Enables / Disables LP printers.
env	Displays environment variables.
eqn	Language processors to assist in describing equations.
ex	Line-editor mode of the vi text editor.
exit	Exit from a program, shell or log you out of a Unix network.
expand	Expand copies of file s.
expr	Evaluate arguments as an expression.
fc	The FC utility lists or edits and re-executes, commands previously entered to an interactive sh.
fg	Continues a stopped job by running it in the foreground
fgrep	Search a file for a fixed-character string.
file	Tells you if the object you are looking at is a file or if it is a directory.
find	Finds one or more files assuming that you know their approximate filenames.
findsmb	List info about machines that respond to SMB name queries on a subnet.
finger	Lists information about the user.
fmt	Simple text formatters.
fold	Filter for folding lines.
for	Shell built-in functions to repeatedly execute action(s) for a selected number of times.
foreach	Shell built-in functions to repeatedly execute action(s) for a selected number of times.
free	Display amount of free and used memory in the system
fromdos	Converts text files between DOS and Unix formats.
fsck	Check and repair a Linux file system.
ftp	Enables ftp access to another terminal.
getfacl	Display discretionary file information.
gprof	The gprof utility produces an execution profile of a program.
grep	Finds text within a file.
groupadd	Creates a new group account.
groupdel	Enables a super user or root to remove a group.
groupmod	Enables a super user or root to modify a group.
gunzip	Expand compressed files.
gview	A programmers text editor.
gvim	A programmers text editor.
gzip	Compress files.
halt	Stop the computer.
hash	Remove internal hash table.
hashstat	Display the hash stats.
head	Displays the first ten lines of a file, unless otherwise stated.
help	If computer has online help documentation installed this command will display it.
history	Display the history of commands typed.
host	DNS lookup utility.
hostid	Prints the numeric identifier for the current host.
hostname	Set or print name of current host system.
id	Shows you the numeric user and group ID on BSD.
ifconfig	Sets up network interfaces.
ifdown	Take a network interface down.
ifup	Bring a network interface up.
init	Process control initialization.
ip	Show / manipulate routing, devices, policy routing and tunnels.
isalist	Display the native instruction sets executable on this platform.
jobs	List the jobs currently running in the background.
join	Joins command forms together.
keylogin	Decrypt the user's secret key.
kill	Cancels a job.
ksh	Korn shell command interpreter.
ld	Link-editor for object files.
ldd	List dynamic dependencies of executable files or shared objects.
less	Opposite of the more command.
lex	Generate programs for lexical tasks.
link	Calls the link function to create a link to a file.
ln	Creates a link to a file.
lo	Allows you to exit from a program, shell or log you out of a Unix network.
locate	List files in databases that match a pattern.
login	Signs into a new system.
logname	Returns users login name.
logout	Logs out of a system.
lp	Prints a file on System V systems.
lpadmin	Configure the LP print service.
lpc	Line printer control program.
lpq	Lists the status of all the available printers.
lpr	Submits print requests.
lprm	Removes print requests from the print queue.
lpstat	Lists status of the LP print services.
ls	Lists the contents of a directory.
mach	Display the processor of the current host.
mail	One of the ways that allows you to read/send E-Mail.
mailcompat	Provide SunOS 4.x compatibility for the Solaris mailbox format.
mailx	Mail interactive message processing system.
make	Executes a list of shell commands associated with each target.
man	Display a manual of a command.
mesg	Control if non-root users can send text messages to you.
mii-tool	View, manipulate media-independent interface status.
mkdir	Create a directory.
mkfs	Build a Linux file system, usually a hard disk partition.
more	Displays text one screen at a time.
mount	Creates a file systems and remote resources.
mt	Magnetic tape control.
mv	Renames a file or moves it from one directory to another directory.
nc	TCP/IP swiss army knife.
neqn	Language processors to assist in describing equations.
netstat	Shows network status.
newalias	Install new elm aliases for user or system.
newform	Change the format of a text file.
newgrp	Log into a new group.
nice	Invokes a command with an altered scheduling priority.
niscat	Display NIS+ tables and objects.
nischmod	Change access rights on a NIS+ object.
nischown	Change the owner of a NIS+ object.
nischttl	Change the time to live value of a NIS+ object.
nisdefaults	Display NIS+ default values.
nisgrep	Utilities for searching NIS+ tables.
nismatch	Utilities for searching NIS+ tables.
nispasswd	Change NIS+ password information.
nistbladm	NIS+ table administration command.
nmap	Network exploration tool and security / port scanner.
nohup	Runs a command even if the session is disconnected or the user logs out.
nroff	Formats documents for display or line-printer.
nslookup	Queries a name server for a host or domain lookup.
on	Execute a command on a remote system, but with the local environment.
onintr	Shell built-in functions to respond to (hardware) signals.
optisa	Determine which variant instruction set is optimal to use.
pack	Shrinks file into a compressed file.
pagesize	Display the size of a page of memory in bytes, as returned by getpagesize.
passwd	Allows you to change your password.
paste	Merge corresponding or subsequent lines of files.
pax	Read / write and writes lists of the members of archive files and copy directory hierarchies.
pcat	Compresses file.
perl	Perl is a programming language optimized for scanning arbitrary text files, extracting information from those text files.
pg	Files perusal filters for CRTs.
pgrep	Examine the active processes on the system and reports the process IDs of the processes
pico	Simple and very easy to use text editor in the style of the Pine Composer.
pine	Command line program for Internet News and Email.
ping	Sends ICMP ECHO_REQUEST packets to network hosts.
pkill	Examine the active processes on the system and reports the process IDs of the processes
poweroff	Stop the computer.
pr	Formats a file to make it look better when printed.
priocntl	Display's or set scheduling parameters of specified process(es)
printf	Write formatted output.
ps	Reports the process status.
pvs	Display the internal version information of dynamic objects within an ELF file.
pwd	Print the current working directory.
quit	Allows you to exit from a program, shell or log you out of a Unix network.
rcp	Copies files from one computer to another computer.
reboot	Stop the computer.
red	Line oriented file editor.
rehash	Recomputes the internal hash table of the contents of directories listed in the path.
remsh	Runs a command on another computer.
repeat	Shell built-in functions to repeatedly execute action(s) for a selected number of times.
replace	A string-replacement utility.
rgview	A programmers text editor.
rgvim	A programmers text editor.
rlogin	Establish a remote connection from your terminal to a remote machine.
rm	Deletes a file without confirmation (by default).
rmail	One of the ways that allows you to read/send E-Mail.
rmdir	Deletes a directory.
rn	Reads newsgroups.
route	Show / manipulate the IP routing table.
rpcinfo	Report RPC information.
rsh	Runs a command on another computer.
rsync	Faster, flexible replacement for rcp.
rview	A programmers text editor.
rvim	A programmers text editor.
s2p	Convert a sed script into a Perl script.
sag	Graphically displays the system activity data stored in a binary data file by a previous sar run.
sar	Displays the activity for the CPU.
screen	Screen manager with VT100/ANSI terminal emulation.
script	Records everything printed on your screen.
sdiff	Compares two files, side-by-side.
sed	Allows you to use pre-recorded commands to make changes to text.
sendmail	Sends mail over the Internet.
set	Set the value of an environment variable.
setenv	Set the value of an environment variable.
setfacl	Modify the Access Control List (ACL) for a file or files.
settime	Change file access and modification time.
sftp	Secure file transfer program.
sh	Runs or processes jobs through the Bourne shell.
shred	Delete a file securely, first overwriting it to hide its contents.
shutdown	Turn off the computer immediately or at a specified time.
sleep	Waits a x amount of seconds.
slogin	OpenSSH SSH client (remote login program).
smbclient	An ftp-like client to access SMB/CIFS resources on servers.
sort	Sorts the lines in a text file.
spell	Looks through a text file and reports any words that it finds in the text file that are not in the dictionary.
split	Split a file into pieces.
stat	Display file or filesystem status.
stop	Control process execution.
strip	Discard symbols from object files.
stty	Sets options for your terminal.
su	Become super user or another user.
sysinfo	Get and set system information strings.
sysklogd	Linux system logging utilities.
tabs	Set tabs on a terminal.
tail	Delivers the last part of the file.
talk	Talk with other logged in users.
tac	Concatenate and print files in reverse.
tar	Create tape archives and add or extract files.
tbl	Preprocessor for formatting tables for nroff or troff.
tcopy	Copy a magnetic tape.
tcpdump	Dump traffic on a network.
tee	Read from an input and write to a standard output or file.
telinit	Process control initialization.
telnet	Uses the telnet protocol to connect to another remote computer.
test	Check file types and compare values.
time	Used to time a simple command.
timex	The timex command times a command; reports process data and system activity.
todos	Converts text files between DOS and Unix formats.
top	Display Linux tasks.
touch	Change file access and modification time.
tput	Initialize a terminal or query terminfo database.
tr	Translate characters.
traceroute	Print the route packets take to network host.
troff	Typeset or format documents.
tty	Print the file name of the terminal connected to standard input.
ul	Reads the named filenames or terminal and does underlining.
umask	Get or set the file mode creation mask.
unalias	Remove an alias.
unhash	Remove internal hash table.
uname	Print name of current system.
uncompress	Uncompressed compressed files.
uniq	Report or filter out repeated lines in a file.
unlink	Call the unlink function to remove the specified file.
unmount	Disconnects a file systems and remote resources.
unpack	Expands a compressed file.
untar	Create tape archives and add or extract files.
until	Execute a set of actions while/until conditions are evaluated TRUE.
unzip	List, test and extract compressed files in a ZIP archive.
useradd	Create a new user or updates default new user information.
userdel	Remove a users account.
usermod	Modify a users account.
vacation	Reply to mail automatically.
vedit	Screen-oriented (visual) display editor based on ex.
vgrind	Grind nice program listings
vi	Screen-oriented (visual) display editor based on ex.
vim	A programmers text editor.
view	A programmers text editor.
w	Show who is logged on and what they are doing.
wait	Await process completion.
wc	Displays a count of lines, words, and characters in a file
whereis	Locate a binary, source, and manual page files for a command.
while	Repetitively execute a set of actions while/until conditions are evaluated TRUE.
which	Locate a command.
who	Displays who is on the system.
whoami	Print effective userid.
whois	Internet user name directory service.
write	Send a message to another user.
X	Execute the X windows system.
xfd	Display all the characters in an X font.
xlsfonts	Server font list displayer for X.
xset	User preference utility for X.
xterm	Terminal emulator for X.
xrdb	X server resource database utility.
yacc	Short for yet another compiler-compiler, yacc is a compiler.
yes	Repeatedly output a line with all specified STRING(s), or 'y'.
yppasswd	Changes network password in the NIS database.
zcat	Compress files.
zip	Compression and file packaging utility.