Sunday, September 11, 2011

Quick reference Linux commands

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
cse – 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')
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
.period – Run commands from a file