ubuntu linux basic commands (cmd)

Here is a list of a collection of basic commands in Ubuntu Linux:
a
adduser = Add users to the system
addgroup = Add group to the system
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
b
= basename Strip directory and suffix from filenames
= bash GNU Bourne-Again Shell
= bc Arbitrary precision calculator language
= bg Send to background
= break out of a loop
= builtin Run a shell builtin
= bzip2 Compress or decompress named file (s)
c
cal = Show calendar
case = conditionally perform a command
cat = Displays the contents of the file
cd = Change directory
cfdisk Partition table manipulator = for Linux
= chgrp Change group ownership
chmod = Change permissions
= chown Change file owner and group
chroot = Run command with a different root directory
= chkconfig System services (runlevel)
= cksum Print CRC checksum and byte count
clear = Clear screen terminal
cmp = Compare two files
comm = Compare two sorted files line by line
command = Run command - ignoring shell functions
= continue Resume the next iteration of a loop
cp = Copy one or more files to another location
= cron daemon runs the command scheduled
= crontab Schedule a command to run at a later time
csplit = Split files into the context - specified pieces
= cut splits files into several sections
d
date = Display or change the date & time
dc = Desk Calculator
dd = Convert and copy a file, write disk headers, boot record
ddrescue = tool to improve data
= declare Declare variables and give them attributes
df = Display disk space
diff = Display the differences between two files
= diff3 Show differences among three files
dig = DNS lookup
dir = list directory contents short
dircolors = Colour setup for `ls'
dirname = Convert all pathname to multiple paths
dirs = View list of directories to remember
= dmesg Print kernel messages & driver
du = Estimate file space usage
e
echo = Display message on screen
egrep = Search files 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 = Run command
exit = Exit from shell
expect = automate applications accessed through terminal free
= expand Convert tabs to spaces
= Set the environment variable export
Evaluate expression expr =
f
false = Do not do anything, did not work
fdformat = Low-level format a floppy disk
= fdisk partition table manipulator for Linux
= fg Send job to foreground
fgrep = Search files for lines that match a fixed string
file = Specify file types
find = Search for files that meet a desired criteria
fmt = Reformat text types
= fold Wrap text to fit a specified width.
for = Expand words, and execute commands
format = Format disks or tapes
free = Show memory usage
fsck = Check and repair file system consistency
FTP = File Transfer Protocol
Define functions macro function =
fuser = Identification / disconnect process is accessing the file
g
= gawk Find and Replace text in a file
Outlining getopts = parameter according to the position
grep = Search files for lines that match a certain pattern
group = Print the name of the user group
= gzip Compress or decompress the file name
h
hash = Considering the whole pathname of a name argument
head = Output the first part of the file
help = Display help for a built-in command
The command history history =
hostname = Print or set system name
i
id = Print user and group id
if = perform commands conditionally
= ifconfig Configure a network interface
= ifdown Stop a network interface
ifup = Starting up network interface
import = Capturing X server screen and save the image to a file
install = Copy files and set attributes
j
join = join lines on a common field
k
Lay = kill running processes
killall = Lay off the process by name
l
less = Display output one screen at a time
let = Perform arithmetic on shell variables
ln = Creating relationships between files
Creating local variables =
locate = Search files
logname = Print login name
= logout Exit a login shell
= look Display lines beginning with a certain string
lpc = printer line Control Program
= lpr Off line print
lprint = Print File / Print file
lprintd = Abort a print job
lprintq = print queue list
= lprm Remove jobs from the print queue
ls = List information about file
= lsof List open files
m
Rebuilding make = group of program
man = manual Help
mkdir = Create a new folder
= mkfifo Make FIFOs (named pipes)
mkisofs = Create hybrid filesystem ISO9660/JOLIET/HFS
mknod = Make block or character special file
more = Display output one screen at a time
mount = Mount the file system
= mtools Manipulate MS-DOS files
mv = Move or rename a file or directory
mmv = mass Move and rename (files)
n
netstat = Information Network
nice = Set the priority of a command or job
nl = Number lines and write files
nohup = Run command immune to hangups
= nslookup Query Internet call server in interactive
o
open = open the file in the default application
op = operator access
p
passwd Modify a user password
paste Merge lines = file
pathchk = Check file name portability
ping = Test a network connection
pkill = terminate running processes
= popd Restore the previous value of the current directory
= pr Prepare files for printing / print
= 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
q
quota = repulse disk usage and limiting
quotacheck = Examine file system for disk usage
quotactl = Set disk quotas
r
= ram ram disk device
= rcp Copy files between two machines
read = Read a line from standard input
readarray = Read from stdin into an array variable
readonly = Mark variables / functions as readonly
Reboot the system reboot =
rename = Rename file
renice = Change priority of running processes
remsync = Synchronize remote files via email
return = Exit a shell function
rev = Reverse lines of a file
rm = Deleting file
rmdir = Remove folder
= rsync Remote file copy (Synchronize file trees)
s
= 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 / delay for a certain period of time
slocate = Search files
sort = Sorting text file
source = Execute commands from a file `. '
split = Split files into fixed-pieces
ssh = Secure Shell client (remote login program)
= strace Trace system calls and signals
su = Substitute user identity
sudo = Run command as another user
sum = Print a checksum for a file
symlink = Make a new name for the file
= sync Synchronize data on disk with memory
t
= tail Output the last part of the file
tar = Tape Archiver
= tee Redirect output to multiple files
test = Evaluate conditional expression
time = Measure Program running time
times = User and system time
touch = Change file timestamps
top = list of 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 sort = Topology
= tty Print filename of terminal on stdin
type = describes the command
u
= ulimit Limit user resources (resources)
umask = The user creates a hidden file
= umount Unmount (not up) devices
= unalias Remove an alias
uname = print system information
unexpand = Convert spaces to tabs
Uniq = Uniquify file
unit = Convert units from one scale to another
= unset Remove variable or function names
= unshar Unpack shell archive records
until = Execute commands (until error)
useradd = Creating a 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
v = verbosely list directory contents (`ls-l-b ')
vdir = verbosely list directory contents (`ls-lb")
vi = Text Editor
= vmstat reports virtual memory statistics
w
watch = Execute / display a program periodically
= wc Print byte, word and line count
whereis = Search user's $ path, man pages and source files for the program
roomates = Search user's $ path for a program file
while = Run command
who = Print all usernames currently logged in
= whoami Print the current user id and name (`id-un ')
wget = Capture web pages or files via HTTP, HTTPS or FTP
write = Send messages to other users
x
xargs = Execute utility, passing constructed argument list
y
= yes Print a string until at interrupt
. = Script run shell commands are now