Unix Commands:

This quick guide lists commands, including a syntax and brief description. For more detail, use:

$man command.

Files and Directories:

Command	Description of the command
cat	Display File contents
cd	Changes Directory to dirname
chgrp	Change File group
chmod	Changing permissions
cp	Copy source file into destination
file	Determine file type
find	Find files
grep	Search files for regular expressions
head	Display first few lines of a file
ln	Create softlink to oldname
ls	Display information about file type.
mkdir	Create a new directory dirname
more	Display data in paginated form.
mv	Move (Rename) a oldname to newname
pwd	Print current working directory.
rm	Remove (Delete) filename.
rmdir	Delete an existing directory provided it is empty
tail	Prints last few lines in a file
touch	Update access and modification time of a file.

Manipulating data:

The contents of files can be compared and altered with the following commands.

Command Description

awk Pattern scanning and processing language

cmp Compare the contents of two files

comm Compare sorted data

cut Cut out selected fields of each line of a file

diff Differential file comparator

expand Expand tabs to spaces

join Join files on some common field

perl Data manipulation language

sed Stream text editor

sort Sort file data

split Split file into smaller files

tr Translate characters

uniq Report repeated lines in a file

wc Count words, lines, and characters

vi Opens vi text editor

vim Opens vim text editor

fmt Simple text formatter

spell Check text for spelling error

ispell Check text for spelling error

emacs GNU project Emacs

ex,edit Line editor

emacs GNU project Emacs

Compressed Files:

Files may be compressed to save space. Compressed files can be created and examined:

Command Description
compress Compress files
gunzip Uncompress gzipped files
gzip GNU alternative compression method
uncompress Uncompress files
unzip List, test and extract compressed files in a ZIP archive
zcat Cat a compressed file
zcmp Compare compressed files
zdiff Compare compressed files
zmore File perusal filter for crt viewing of compressed text

Getting Information:

Various Unix manuals and documentation are available on-line. The following Shell commands give information:

Command Description
apropos Locate commands by keyword lookup
info Displays command information pages online
man Displays manual pages online
whatis Search the whatis database for complete words.
yelp GNOME help viewer

Network Communication:

These following commands are used to send and receive files from a local UNIX hosts to the remote host around the world.

Command Description
ftp File transfer program
rcp Remote file copy
rlogin Remote login to a UNIX host
rsh Remote shell
tftp Trivial file transfer program
telnet Make terminal connection to another host
ssh Secure shell terminal or command connection
scp Secure shell remote file copy
sftp secure shell file transfer program

Some of these commands may be restricted at your computer for security reasons.

Messages between Users:

The UNIX systems support on-screen messages to other users and world-wide electronic mail:

Command Description
evolution GUI mail handling tool on Linux
mail Simple send or read mail program
mesg Permit or deny messages
parcel Send files to another user
pine Vdu-based mail utility
talk Talk to another user
write Write message to another user

Programming Utilities:

The following programming tools and languages are available based on what you have installed on your Unix.

Command Description
dbx Sun debugger
gdb GNU debugger
make Maintain program groups and compile programs.
nm Print program's name list
size Print program's sizes
strip Remove symbol table and relocation bits
cb C program beautifier
cc ANSI C compiler for Suns SPARC systems
ctrace C program debugger
gcc GNU ANSI C Compiler
indent Indent and format C program source
bc Interactive arithmetic language processor
gcl GNU Common Lisp
perl General purpose language
php Web page embedded language
py Python language interpreter
asp Web page embedded language
CC C++ compiler for Suns SPARC systems
g++ GNU C++ Compiler
javac JAVA compiler
appletvieweir JAVA applet viewer
netbeans Java integrated development environment on Linux
sqlplus Run the Oracle SQL interpreter
sqlldr Run the Oracle SQL data loader
mysql Run the mysql SQL interpreter

Misc Commands:

These commands list or alter information about the system:

Command Description
chfn Change your finger information
chgrp Change the group ownership of a file
chown Change owner
date Print the date
determin Automatically find terminal type
du Print amount of disk usage
echo Echo arguments to the standard options
exit Quit the system
finger Print information about logged-in users
groupadd Create a user group
groups Show group memberships
homequota Show quota and file usage
iostat Report I/O statistics
kill Send a signal to a process
last Show last logins of users
logout log off UNIX
lun List user names or login ID
netstat Show network status
passwd Change user password
passwd Change your login password
printenv Display value of a shell variable
ps Display the status of current processes
ps Print process status statistics
quota -v Display disk usage and limits
reset Reset terminal mode
script Keep script of terminal session
script Save the output of a command or process
setenv Set environment variables
stty Set terminal options
time Time a command
top Display all system processes
tset Set terminal mode
tty Print current terminal name
umask Show the permissions that are given to view files by default
uname Display name of the current system
uptime Get the system up time
useradd Create a user account
users Print names of logged in users
vmstat Report virtual memory statistics
w Show what logged in users are doing
who List logged in users

Linux Commands:

An A-Z Index of the Bash command line for Linux.


  alias    Create an alias •

  apropos  Search Help manual pages (man -k)

  apt-get  Search for and install software packages (Debian/Ubuntu)

  aptitude Search for and install software packages (Debian/Ubuntu)

  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    Exit from a loop •
  builtin  Run a shell builtin
  bzip2    Compress or decompress named file(s)
c
  cal      Display a calendar
  case     Conditionally perform a command
  cat      Concatenate and print (display) the content of files
  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
  chkconfig System services (runlevel)
  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
d
  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
  dmesg    Print kernel & driver messages 
  du       Estimate file space usage
e
  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
f
  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
  fuser    Identify/kill the process that is accessing a file
g
  gawk     Find and Replace text within file(s)
  getopts  Parse positional parameters
  grep     Search file(s) for lines that match a given pattern
  groupadd Add a user security group
  groupdel Delete a group
  groupmod Modify a group
  groups   Print group names a user is in
  gzip     Compress or decompress named file(s)
h
  hash     Remember the full pathname of a name argument
  head     Output the first part of file(s)
  help     Display help for a built-in command •
  history  Command History
  hostname Print or set system name
i
  iconv    Convert the character set of a file
  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
j
  jobs     List active jobs •
  join     Join lines on a common field
k
  kill     Stop a process from running
  killall  Kill processes by name
l
  less     Display output one screen at a time
  let      Perform arithmetic on shell variables •
  link     Create a link to a file 
  ln       Create a symbolic link to a file
  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
m
  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
  mtr      Network diagnostics (traceroute/ping)
  mv       Move or rename files or directories
  mmv      Mass Move and rename (files)
n
  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
  notify-send  Send desktop notifications
  nslookup Query Internet name servers interactively
o
  open     Open a file in its default application
  op       Operator access 
p
  passwd   Modify a user password
  paste    Merge lines of files
  pathchk  Check file name portability
  ping     Test a network connection
  pkill    Stop processes from running
  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
  pv       Monitor the progress of data through a pipe 
  pwd      Print Working Directory
q
  quota    Display disk usage and limits
  quotacheck Scan a 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   Reboot the system
  rename   Rename files
  renice   Alter priority of running processes 
  remsync  Synchronize remote files via email
  return   Exit a shell function
  rev      Reverse lines of a file
  rm       Remove files
  rmdir    Remove folder(s)
  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 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
  suspend  Suspend execution of this shell •
  sync     Synchronize data on disk with memory
t
  tail     Output the last part of file
  tar      Store, list or extract files in an archive
  tee      Redirect output to multiple files
  test     Evaluate a conditional expression
  time     Measure Program running time
  timeout  Run a command with a time limit
  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 •
u
  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)
  uptime   Show uptime
  useradd  Create new user account
  userdel  Delete a 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 -l -b')
  vi       Text Editor
  vmstat   Report virtual memory statistics
w
  wait     Wait for a process to complete •
  watch    Execute/display a program periodically
  wc       Print byte, word, and line counts
  whereis  Search the user's $path, man pages and source files for a program
  which    Search the user's $path for a program file
  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
  write    Send a message to another user 
x
  xargs    Execute utility, passing constructed argument list(s)
  xdg-open Open a file or URL in the user's preferred application.
  yes      Print a string until interrupted
  zip      Package and compress (archive) files.
  .        Run a command script in the current shell
  !!       Run the last command again
  ###      Comment / Remark

                                                    For more information visit http://www.er.uqam.ca/nobel/r10735/unixcomm.html

Important & Basic Concepts to be known

Sunday, December 29, 2013

Basic Unix & Linux Commands with their Description...

An A-Z Index of the Bash command line for Linux.