Linux Commands
alias * Create an alias
apropos * Search Help manual pages (man -k)
apt-get * Search for and install software packages (Debian)
aspell * Spell Checker
awk * Find and Replace text, database sort/validate/index
bash * GNU Bourne-Again SHell
bc * Arbitrary precision calculator language
bg * Send to background
break * Exit from a loop
builtin * Run a shell builtin
bzip2 * Compress or decompress named file(s)
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 * Convert and copy a file, write disk headers, boot records
ddrescue *Data recovery tool
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
dig * DNS lookup
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
egrep * Search file(s) for lines that match an extended expression
eject * Eject removable media
enable * Enable and disable builtin shell commands
env * Environment variables
ethtool * Ethernet card settings
eval * Evaluate several commands/arguments
exec * Execute a command
exit * Exit the shell
expect * Automate arbitrary applications accessed over a terminal
expand * Convert tabs to spaces
export * Set an environment variable
expr * Evaluate expressions
false * Do nothing, unsuccessfully
fdformat * Low-level format a floppy disk
fdisk * Partition table manipulator for Linux
fg * Send job to foreground
fgrep * Search file(s) for lines that match a fixed string
file * Determine file type
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 * File system consistency check and repair
ftp * File Transfer Protocol
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
ifconfig * Configure a network interface
ifdown * Stop a network interface
ifup * Start a network interface up
import * Capture an X server screen and save the image to file
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
look * Display lines beginning with a given string
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)
lsof * List open files
make * Recompile a group of programs
man * Help manual
mkdir * Create new folder(s)
mkfifo * Make FIFOs (named pipes)
mkisofs * Create an hybrid ISO9660/JOLIET/HFS filesystem
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
netstat * Networking information
nice * Set the priority of a command or job
nl * Number lines and write files
nohup * Run a command immune to hangups
nslookup * Query Internet name servers interactively
open * Open a file in its default application
op * Operator access
passwd * Modify a user password
paste * Merge lines of files
pathchk * Check file name portability
ping * Test a network connection
popd * Restore the previous value of the current directory
pr * Prepare 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
renice * Alter priority of running processes
remsync * Synchronize remote files via email
return * Exit a shell function
rm * Remove files
rmdir * Remove folder(s)
rsync * Remote file copy (Synchronize file trees)
screen * Multiplex terminal, run remote shells via ssh
scp * Secure copy (remote file copy)
sdiff * Merge two files interactively
sed * Stream Editor
select * Accept keyboard input
seq * Print numeric sequences
set * Manipulate shell variables and functions
sftp * Secure File Transfer Program
shift * Shift positional parameters
shopt * Shell Options
shutdown * Shutdown or restart linux
sleep * Delay for a specified time
slocate * Find files
sort * Sort text files
source * Run commands from a file `.'
split * Split a file into fixed-size pieces
ssh * Secure Shell client (remote login program)
strace * Trace system calls and signals
su * Substitute user identity
sudo * Execute a command as another user
sum * Print a checksum for a file
symlink * Make a new name for a file
sync * Synchronize data on disk with memory
tail * Output the last part of files
tar * Tape ARchiver
tee * Redirect output to multiple files
test * Evaluate a conditional expression
time * Measure Program running time
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
vmstat * Report virtual memory statistics
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')
Wget * Retrieve web pages or files via HTTP, HTTPS or FTP
xargs * Execute utility, passing constructed argument list(s)
yes * Print a string until interrupted
. * Run a command script in the current shell
### * Comment / Remark