Unix Command Summary

Access Control

exit - terminate a shell (see "man sh" or "man csh")
logout - sign off; end session (C shell and bash shell only; no man
page)
passwd - change login password
rlogin - log in remotely to another UNIX system
slogin - secure version of rlogin

Communications

from - list senders of mail
Mail - send and receive mail
mesg - permit or deny terminal messages and talk requests
pine - send and receive mail (easiest for new users)
talk - talk to another logged-in user (full screen)
write - write to another logged-in user

Programming Tools

ar - archive and library maintainer
as - assembler, specific to each machine architecture
awk - pattern scanning and processing language
/bin/time - time a command
cc - C compiler (xlc on ADS)
crontab - maintain periodic tasks
csh - C shell command interpreter
dbx - source-level debugging program
f77 - Fortran compiler (xlf on ADS)
gdb - GNU Project debugger
gprof - display profile of called routines
kill - kill a process
ld - the UNIX loader
lex - generate lexical analysis programs
lint - check C source code
make - maintain large programs
maple - symbolic mathematics program
nice - run a command at low priority (see "man nice" or "man csh")
nohup - run a command immune to hangups
pc - Pascal compiler (xlp on ADS)
perl - Popular script interpreter
prof - display profile data
ranlib - convert archives to random libraries
sh - Bourne shell command interpreter
yacc - generate input parsing programs

Documentation

apropos - locate commands by keyword lookup
info - start the InfoExplorer program (ADS only)
man - find manual information about commands
/usr/bin/X11/dxbook - start the BookReader program (UTS only)
whatis - describe what a command is
whereis - locate source, binary, or man page for a program

Editors

ed - line-oriented text editor
emacs - screen-oriented text editor
ex - line-oriented text editor
pico - simple, screen-oriented text editor (easiest for new users)
sed - stream-oriented text editor
vi - full-screen text editor
vim - full-screen text editor ("vi-improved")

File and Directory Management

cd - change working directory
chmod - change the protection of a file or directory
cmp - compare two files
comm - select/reject lines common to two sorted files
compress - compress a file
cp - copy files
crypt - encrypt/decrypt files (CCWF only)
diff - compare the contents of two ASCII files
file - determine file type
grep - search a file for a pattern
ln - make a link to a file
ls - list the contents of a directory
mkdir - create a directory
mv - move or rename files and directories
pwd - show the full pathname of your working directory
quota - display disk usage and limits
rm - delete (remove) files
rmdir - delete (remove) directories
sort - sort or merge files
tee - copy input to standard output and other files
tr - translate characters
umask - change default file protections
uncompress - restore compressed file
uniq - report (or delete) repeated lines in a file
wc - count lines, words, and characters in a file

File Display and Printing

cat - show the contents of a file; catenate files
fold - fold long lines to fit output device
head - show first few lines of a file
lpq - examine the printer spooling queue
lpr - print a file
lprm - remove jobs from the printer spooling queue
more - display a file, one screen at a time
page - like "more", but prints screens top to bottom
pr - paginate a file for printing
tail - show the last part of a file
zcat - display a compressed file

File Transfer
ftp - transfer files between network hosts
rcp - transfer files between networked UNIX hosts
scp - secure version of rcp
rz - receive files using ZMODEM protocol
sz - send files using ZMODEM protocol

Miscellaneous

alias - define synonym commands
chquota - change disk quota on ACITS UNIX systems
chsh - change default login shell
clear - clear terminal screen
echo - echo arguments
learn - request computer-aided instruction
pbm - portable bitmap manipulation programs
popd - pop the directory stack (C shell only)
pushd - push directory on stack (C shell only)
script - make typescript of terminal session
setenv - set an environment variable (C shell only)
stty - set terminal options

News/Networks
netstat - show network status (or /usr/sbin/netstat)
Pnews - submit USENET news articles
rlogin - login remotely on another UNIX system
slogin - secure version of rlogin
tin - read/post USENET news articles
trn - read/post USENET news articles using threaded news reader
rsh - run shell or command on another UNIX system
ssh - secure-shell version of rsh
telnet - run Telnet to log in to remote host

Process Control
(The following commands function under the C shell, bash, and ksh. They do not have separate man pages.)

bg - put suspended process into background
fg - bring process into foreground
jobs - list processes
^y - suspend process at next input request
^z - suspend current process

Status Information

spend - lists year-to-date ACITS UNIX charges
date - show date and time
df - summarize free disk space
du - summarize disk space used
env - display environment
finger - look up user information
history - list previously issued commands (C shell, bash, and ksh
only)
last - indicate last login of users
lpq - examine spool queue
manpath - show search path for man pages
printenv - print out environment
ps - show process status
pwd - print full pathname of working directory
set - set shell variables (C shell, bash, and ksh only)
stty - set terminal options
uptime - show system load, how long system has been up
w - show who is on system, what command each job is executing
who - show who is logged onto the system
whois - Internet user name directory service

Text Processing

addbib - create or extend bibliographic database
checknr - check nroff/troff files
col - filter reverse line feeds
diction - identify wordy sentences
diffmk - mark differences between files
dvips - convert TeX DVI files into PostScript
eqn - typeset mathematics with troff
explain - explain phrases found by diction program
grap - pic preprocessor for drawing graphs (ADS only)
hyphen - find hyphenated words
indxbib - build inverted index for a bibliography, find references
ispell - check spelling interactively
latex - format text
lookbib - find bibliography references
macref - make cross-reference listing of nroff/troff macro files
ndx - create a subject-page index for a document
neqn - format mathematics with nroff
nroff - format text for simple display
pic - make simple pictures for troff input
psdit - filter troff output for Apple LaserWriter
ptx - make permuted index
refer - insert references from bibliographic databases
roffbib - run off bibliographic database
sortbib - sort bibliographic database
spell - find spelling errors
style - analyze surface characteristics of a document
tbl - format tables for nroff/troff
tex - format text
tpic - convert pic source files into TeX commands
troff - format text

Source: http://www.utexas.edu/cc/docs/ccug1/commandsum.html

Also see: http://www.math.utah.edu/lab/unix/unix-commands.html