IT COMMUNITY

alias  ->  Create an alias
awk  ->  Find and Replace text, database sort/validate/index
break  ->  Exit from a loop
builtin  ->  Run a shell builtin
cal  ->  Display a calendar
case  ->  Conditionally perform a command
cat  ->  Display the contents of a file
cd  ->  Change Directory
cfdisk  ->  Partition table manipulator for Linux
chgrp  ->  Change group ownership
chmod  ->  Change access permissions
chown  ->  Change file owner and group
chroot  ->  Run a command with a different root directory
cksum  ->  Print CRC checksum and byte counts
clear  ->  Clear terminal screen
cmp  ->  Compare two files
comm  ->  Compare two sorted files line by line
command  ->  Run a command – ignoring shell functions
continue  ->  Resume the next iteration of a loop
cp  ->  Copy one or more files to another location
cron  ->  Daemon to execute scheduled commands
crontab  ->  Schedule a command to run at a later time
csplit  ->  Split a file into context-determined pieces
cut  ->  Divide a file into several parts
date  ->  Display or change the date & time
dc  ->  Desk Calculator
dd  ->  Data Dump – Convert and copy a file
declare  ->  Declare variables and give them attributes
df  ->  Display free disk space
diff  ->  Display the differences between two files
diff3  ->  Show differences among three files
dir  ->  Briefly list directory contents
dircolors  ->  Colour setup for `ls’
dirname  ->  Convert a full pathname to just a path
dirs  ->  Display list of remembered directories
du  ->  Estimate file space usage
echo  ->  Display message on screen
ed  ->  A line-oriented text editor (edlin)
egrep  ->  Search file(s) for lines that match an extended expression
eject  ->  Eject CD-ROM
enable  ->  Enable and disable builtin shell commands
env  ->  Display, set, or remove environment variables
eval  ->  Evaluate several commands/arguments
exec  ->  Execute a command
exit  ->  Exit the shell
expand  ->  Convert tabs to spaces
export  ->  Set an environment variable
expr  ->  Evaluate expressions
factor  ->  Print prime factors
false  ->  Do nothing, unsuccessfully
fdformat  ->  Low-level format a floppy disk
fdisk  ->  Partition table manipulator for Linux
fgrep  ->  Search file(s) for lines that match a fixed string
find  ->  Search for files that meet a desired criteria
fmt  ->  Reformat paragraph text
fold  ->  Wrap text to fit a specified width.
for  ->  Expand words, and execute commands
format  ->  Format disks or tapes
free  ->  Display memory usage
fsck  ->  Filesystem consistency check and repair.
function  ->  Define Function Macros
gawk  ->  Find and Replace text within file(s)
getopts  ->  Parse positional parameters
grep  ->  Search file(s) for lines that match a given pattern
groups  ->  Print group names a user is in
gzip  ->  Compress or decompress named file(s)
hash  ->  Remember the full pathname of a name argument
head  ->  Output the first part of file(s)
history  ->  Command History
hostname  ->  Print or set system name
id  ->  Print user and group id’s
if  ->  Conditionally perform a command
import  ->  Capture an X server screen and save the image to file
info  ->  Help info
install  ->  Copy files and set attributes
join  ->  Join lines on a common field
kill  ->  Stop a process from running
less  ->  Display output one screen at a time
let  ->  Perform arithmetic on shell variables
ln  ->  Make links between files
local  ->  Create variables
locate  ->  Find files
logname  ->  Print current login name
logout  ->  Exit a login shell
lpc  ->  Line printer control program
lpr  ->  Off line print
lprint  ->  Print a file
lprintd  ->  Abort a print job
lprintq  ->  List the print queue
lprm  ->  Remove jobs from the print queue
ls  ->  List information about file(s)
m4  ->  Macro processor
man  ->  Help manual
mkdir  ->  Create new folder(s)
mkfifo  ->  Make FIFOs (named pipes)
mknod  ->  Make block or character special files
more  ->  Display output one screen at a time
mount  ->  Mount a file system
mtools  ->  Manipulate MS-DOS files
mv  ->  Move or rename files or directories
nice  ->  Set the priority of a command or job
nl  ->  Number lines and write files
nohup  ->  Run a command immune to hangups
passwd  ->  Modify a user password
paste  ->  Merge lines of files
pathchk  ->  Check file name portability
popd  ->  Restore the previous value of the current directory
pr  ->  Convert text files for printing
printcap  ->  Printer capability database
printenv  ->  Print environment variables
printf  ->  Format and print data
ps  ->  Process status
pushd  ->  Save and then change the current directory
pwd  ->  Print Working Directory
quota  ->  Display disk usage and limits
quotacheck  ->  Scan a file system for disk usage
quotactl  ->  Set disk quotas
ram  ->  ram disk device
rcp  ->  Copy files between two machines.
read  ->  read a line from standard input
readonly  ->  Mark variables/functions as readonly
remsync  ->  Synchronize remote files via email
return  ->  Exit a shell function
rm  ->  Remove files
rmdir  ->  Remove folder(s)
rpm  ->  Remote Package Manager
rsync  ->  Remote file copy (Synchronize file trees)
screen  ->  Terminal window manager
sdiff  ->  Merge two files interactively
sed  ->  Stream Editor
select  ->  Accept keyboard input
seq  ->  Print numeric sequences
set  ->  Manipulate shell variables and functions
shift  ->  Shift positional parameters
shopt  ->  Shell Options
shutdown  ->  Shutdown or restart linux
sleep  ->  Delay for a specified time
sort  ->  Sort text files
source  ->  Run commands from a file `.’
split  ->  Split a file into fixed-size pieces
su  ->  Substitute user identity
sum  ->  Print a checksum for a file
symlink  ->  Make a new name for a file
sync  ->  Synchronize data on disk with memory
tac  ->  Concatenate and write files in reverse
tail  ->  Output the last part of files
tar  ->  Tape ARchiver
tee  ->  Redirect output to multiple files
test  ->  Evaluate a conditional expression
time  ->  Measure Program Resource Use
times  ->  User and system times
touch  ->  Change file timestamps
top  ->  List processes running on the system
traceroute  ->  Trace Route to Host
trap  ->  Run a command when a signal is set(bourne)
tr  ->  Translate, squeeze, and/or delete characters
true  ->  Do nothing, successfully
tsort  ->  Topological sort
tty  ->  Print filename of terminal on stdin
type  ->  Describe a command
ulimit  ->  Limit user resources
umask  ->  Users file creation mask
umount  ->  Unmount a device
unalias  ->  Remove an alias
uname  ->  Print system information
unexpand  ->  Convert spaces to tabs
uniq  ->  Uniquify files
units  ->  Convert units from one scale to another
unset  ->  Remove variable or function names
unshar  ->  Unpack shell archive scripts
until  ->  Execute commands (until error)
useradd  ->  Create new user account
usermod  ->  Modify user account
users  ->  List users currently logged in
uuencode  ->  Encode a binary file
uudecode  ->  Decode a file created by uuencode
v  ->  Verbosely list directory contents (`ls -l -b’)
vdir  ->  Verbosely list directory contents (`ls -l -b’)
vi  ->  Text Editor
watch  ->  Execute/display a program periodically
wc  ->  Print byte, word, and line counts
whereis  ->  Report all known instances of a command
which  ->  Locate a program file in the user’s path.
while  ->  Execute commands
who  ->  Print all usernames currently logged in
whoami  ->  Print the current user id and name (`id -un’)
xargs  ->  Execute utility, passing constructed argument list(s)
yes  ->  Print a string until interrupted