Unix Command Summary

Command	Description
ac	ac prints  out  a  report  of connect time, in hours, based on the logins/logouts in the current wtmp file.  A total is also printed out.
alias	alias with no arguments or with the -p option prints the list of aliases in the form alias name=value on standard output.  When arguments are supplied, an alias is defined for each name whose value is given.  A trailing space in value causes the next word to be checked for alias substitution when the alias is expanded.  For each name in the argument list for which no value is supplied, the name and value of the alias is printed.   alias returns true unless a name is given for which no alias has been defined.
at	at and batch read commands from standard  input  or  a  specified  file which are to be executed at a later time. at  executes commands at a specified time.  atq lists  the  user’s  pending  jobs, unless the user is the superuser; in that case, everybody’s jobs are listed.   The format of the output lines, one for each job,is: Job number; date;hour; and job class.  atrm deletes jobs identified by their job number.  batch executes commands when system  load  levels  permit;  in  other words,  when  the  load  average  drops below 0.8, or the value specified in the invocation of atrun.
awk	Gawk is the GNU Project’s implementation of the AWK programming language. Gawk - pattern scanning and processing language
basename	Print name with any leading directory components removed.  If specified, also remove a trailing suffix.
bc	bc is a calculator that supports arbitrary precision numbers with interactive execution of statements.
bg	Resume the suspended job jobspec in the background, as if it had been started  with  &.
break	Exit from within a for, while, until, or select loop regardless of the loop condition.
cal	cal displays a simple calendar.  If arguments are not specified, the current month is displayed.
cancel	Cancel jobs
cat	Concatenate files and print on the standard output
chdir	chdir changes the current directory to that specified in path.
chfn	chfn is used to change finger information.   This information is stored in the /etc/passwd file, and is displayed by the finger program.
chgrp	Change the group membership files.
chmod	Change file access permissions
chown	Change file owner and group
chsh	Change the user’s login shell
cksum	Checksum and count the bytes in a file
clear	Clears the screen, if possible.
cmp	The cmp utility compares two files of any type and writes the results to the standard output.
col	Filter reverse line feeds from input
comm	Compare two sorted files line by line
compress	compress, uncompress, zcat - compress and expand data
continue	Resume the next iteration of the enclosing for, while, until, or select loop.
cp	Copy files and directories
cpio	Copy files to and from archives
crontab	Maintain crontab files for individual users
csplit	Split a file into sections determined by context lines
ctags	Generate tag files for source code
cut	Remove sections from each line of files
date	Print or set the system date and time
df	Report filesystem disk space usage
diff	Find differences between two files
du	Estimate file space usage
echo	Display a line of text
ed	Ed is a line-oriented text editor.  It is used to create, display, modify and manipulate text files.
egrep	Grep, egrep, fgrep - print lines matching a pattern
emacs	Text editor
env	Run a program in a modified environment
exit	Cause  the  shell  to exit
expand	Convert tabs in each file to spaces, writing to standard output.
expr	Evaluate and print  the  value of expression to standard output
false	Exit with a status code indicating failure.
fg	Resume job in the foreground, and make it the  current  job
fgrep	Grep, egrep, fgrep - print lines matching a pattern
file	Determine file type
find	Search for files in a directory hierarchy
finger	User information lookup program
fmt	Simple optimal text formatter
fold	Wrap each input line to fit in specified width
ftp	Basic file transfer program
getfacl	Get file access control lists
grep	Grep, egrep, fgrep - print lines matching a pattern
groupadd	Create a new group
groupdel	Delete a group
groupmod	Modify a group
gunzip	Expand compressed files
gzip	Compress files
halt	halt, reboot, poweroff - stop the system
hash	For each name, the full file name of the command  is  determined by searching the directories in $PATH and remembered
head	Output the first part of files
help	Display  helpful information about builtin commands
history	Display recently executed commands
hostname	Show or set the system’s host name
id	Print information for USERNAME, or the current user
ifconfig	Display or configure the kernel-resident network interfaces
jobs	Lists the active jobs
join	Join lines of two files on a common field.  For  each  pair of input lines with identical join fields, write a line to standard output
kill	Terminate a process
ld	Linker.  ld  combines a number of object and archive files, relocates their data and ties up symbol references
ldd	Print shared library dependencies
less	less is a program similar to more , but it allows backward  movement in the file as well as forward movement
lex	Used for pattern matching on text
ln	Make links between files
locate	Security Enhanced version of the GNU locate.  It provides a secure way to index and quickly search  for files on the system
login	login is used  when  signing  onto  a system.  It can also be used to switch from one user to another at any time
logname	Print the name of the current user
logout	Exit a login shell
lp	Submits files for printing or alters a pending job
lpadmin	Configures printer and class queues provided by CUPS. It can also be used to set the server default printer or class.
lpc	Provides limited control over printer and class queues provided by CUPS. It can also be used to query the state of queues.
lpq	Shows  the  current print queue status on the named printer
lpr	Submits files for printing
lprm	Cancels  print  jobs  that  have been queued for printing
lpstat	Displays status information about the current classes, jobs, and printers
ls	List directory contents
mail	Send and receive mail
make	The purpose of the make utility is  to  determine  automatically  which pieces of a large program need to be recompiled and issue the commands to recompile them
man	Formats and displays the on-line manual pages
mesg	Controls  the write  access to the user’s terminal by others
mkdir	Make directories
more	more is a filter for paging through text one screenful at a time
mount	Mount a file system
mt	Control magnetic tape drive operation
mv	Move or rename files
neqn	Format equations for ASCII output
netstat	Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships
newgrp	Log in to a new group
nice	Run a program with modified scheduling priority
nohup	Run a command immune to hangups, with output to a non-tty
nslookup	Query Internet name servers interactively
passwd	Update a user’s authentication tokens(s)
paste	Merge lines of files.  It write  lines  consisting  of  the sequentially corresponding lines from each file, separated by tabs, to standard output
perl	Practical Extraction and Report Language
pgrep	Looks through the currently running processes and lists the  process  ids which match the selection criteria to stdout
ping	Uses the ICMP protocol’s mandatory ECHO_REQUEST datagram to elicit an  ICMP  ECHO_RESPONSE from a host or gateway
pkill	Will send the specified signal, by default SIGTERM, to each process instead of listing them on stdout
poweroff	Halt, reboot, poweroff - stop the system
pr	Paginate or columnate file(s) for printing
printf	Format and print data to the standard output
ps	Report process status
pwd	Print name of current/working directory
rcp	Remote file copy … copies files between machines
reboot	Halt, reboot, poweroff - stop the system
red	ed is a line-oriented text editor.  It is used to create, display, modify and otherwise manipulate text files.  red is a  restricted ed:  it can  only  edit files in the current directory and cannot execute shell commands.
rlogin	Remote login
rm	Remove files or directories
rmail	Handle remote mail received via uucp
rmdir	Remove empty directories
rpcinfo	Report remote procedure call (RPC) information.  It makes a RPC call to a RPC server and reports what it finds.
rsh	Remote shell
s2p	Psed - A stream editor that reads the input stream consisting of the specified files (or standard input, if none are given), processes it line by line by applying a script consisting of edit commands, and writes resulting lines to standard output.
sar	Collect, report, or save system activity information
script	Makes a typescript of everything printed on a terminal
sdiff	Find differences between two files and merge interactively
sed	A stream editor.  A stream editor is used to perform basic text transformations on an input stream
sendmail	An electronic mail transport agent that sends a message to one or more recipients, routing the message over whatever networks are necessary
set	Display, set or unset shell attributes.
setenv	Change or add an environment variable
setfacl	Set file access control lists
sh	The bourne shell.  bash is an bourne-compatible command language interpreter that executes commands read from the standard input or from a file.
shutdown	Brings the system down in a secure way.  All logged-in users are notified that the system is going down, and login is blocked.
sleep	Delay for a specified amount of time or pause for number of seconds
sort	Sort lines of text files
split	Split a file into pieces
stty	Change and print terminal line settings
su	Change the effective user id and group id to that of another user
sudo	Execute a command as another user.  It allows a permitted user to execute a command as the superuser or another user, as specified in the sudoers file
sysinfo	Returns information on overall system statistics
tail	Output the last part of files
tar	The tar archiving utility
tee	Read from standard input and write to standard output and files
telnet	The  telnet  command is used to communicate with another host using the TELNET protocol
time	Time a simple command or give resource usage
touch	Update  the  access  and modification times of each file to the current time
tput	Initialize a terminal or query terminfo database
tr	Translate, squeeze, and/or delete characters from standard input, writing to standard output
traceroute	Print the route packets take to a network host
troff	The troff processor of the groff text formatting system
ul	Do underlining
umask	Set the user file-creation mask
unalias	Remove  a  named alias  from  the list of defined aliases
uname	Print certain system information
uncompress	Expand compressed data
uniq	Remove duplicate lines from a sorted file
useradd	Create a new user or update default new user information
userdel	Delete a user account and related files
usermod	Modify a user account
vi	A powerful text editor.
view	Start the vi editor in read-only mode
wait	Wait for the specified process and return its termination status.
wc	Print byte, word, and newline counts for each file, and a total line if more than one file is specified.
whereis	Locate the binary, source, and manual page files for a command
which	Shows the full path of shell commands
who	Show who is logged on
whois	whois searches Whois servers for the named object.
X	The X Window System is a network transparent window system which runs on a wide range of computing and graphics machines
xfd	Display all the characters in an X font
xlsfonts	Server font list displayer for X
xrdb	X server resource database utility
xset	User preference utility for X
xterm	The xterm program is a terminal emulator for the X Window System
zcat	Compress or expand files