Create an alias. Aliases allow a string to be substituted for a word. An alias can be used as the first word of any simple command.

      alias [-p] [name[=value] ...]

      unalias [-a] [name...]

   -p   Print the current values

   -a   Remove All aliases

When arguments are supplied, an alias is defined for each name whose value is given. A trailing space in value causes the next word to be checked for alias
substitution when the alias is expanded.

If no value is given, (or with the -p option) alias will print a list of Aliases along with their current values. For each name in the argument list for which no value is supplied, the name and value of the alias is printed.

Alias returns true unless a name is given for which no alias has been defined.

name can not be `alias’ or `unalias’.

unalias can be used to remove each name from the list of defined aliases.

Alias substitution
The shell maintains a list of aliases which can be set, unset and printed by the alias and unalias commands. After a command line is parsed into simple commands the first word of each command, left-to-right, is checked to see if it has an alias. If so, the first word is replaced by the alias. If the alias contains a history reference, it undergoes History substitution (q.v.) as though the original command were the previous input line. If the alias does not contain a history reference, the argument list is left untouched.

Thus if the alias for ls were ls -l the command ls /usr would become ls -l /usr, the argument list here being undisturbed. If the alias for lookup were grep !^ /etc/passwd‘ then lookup bill would become grep bill /etc/passwd.

Aliases can be used to introduce parser metasyntax. For example, alias print ‘pr \!* | lpr’ defines a command (print) which pr‘s its arguments to the line printer.

The first word of the replacement text is tested for aliases, but a word that is identical to an alias being expanded is not expanded a second
time. This means that you can alias ls to ls -F, for instance, and bash does not try to recursively expand the replacement text.


Create an alias ‘c’ that will clear the screen:
$ alias c=’clear’

Create an alias ‘ls’ that will change the default action of ls:
$ alias ls=’ls –classify’
$ ls
$ unalias ls

More aliases for ls:
$ alias la=’ls -lAXh –color=always’   #Show all, sort by extension
$ alias ls-al=’ls -al’   #fix typo missing space
$ alias l=”ls -l”
$ alias la=”ls -la”

Use alias to fix missing space typos:
$ alias cd..=’cd ..’
alias ..=’cd ..’

Display the working directory
$ alias .=’echo $PWD’

Prevent accidental deletions by making rm interactive:
$ alias rm=’rm -i’

Shorten apt-get installation commands:
$ alias canhaz=’sudo apt-get install’

Run firefox and open a specific website:
$ alias fftr=’/Applications/’

Produce a custom prompt to display which machine you are on, the current folder, and the number of the current command:

   $ alias cd='cd \!*; set currDir = `basename $cwd`; set currDir = `echo
   " ! >"`; set prompt = "${currDir} "'
   $ cd $cwd

<Mac_One:Work-folder 15 >

Making an alias permanent:

Assuming you have the BASH shell, then use your favorite text editor to edit or create a file called ~/.bash_aliases and add your alias commands.

alias is a bash built-in command.

“There are many reasons why novelists write, but they all have one thing in common – a need to create an alternative world” ~ John Fowles


Alias man page –
env – Display, set, or remove environment variables
echo – Display message on screen
set – Set a shell variable
shift – Shift positional parameters

Apple OS X command line

An A-Z Index of the Apple OS X command line

You can get more from


  alias     Create an alias •
  alloc     List used and free memory
  apropos   Search the whatis database for strings
  asr       Apple Software Restore
  awk       Find and Replace text within file(s)
  basename  Convert a full pathname to just a filename
  bash      Bourne-Again SHell
  bg        Send to background •
  bind      Display readline key and function bindings •
  bless     Set volume bootability and startup disk options
  break     Exit from a For, While, Until or Select loop •
  builtin   Execute a shell builtin •
  bzip2     Compress or decompress files
  cal       Display a calendar
  calendar  Reminder Service
  caller    Return the context of a subroutine call •
  case      Conditionally perform a command •
  cat       Concatenate and print (display) the content of files
  cd        Change Directory •
  chflags   Change a file or folder's flags
  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 (not a function) •
  complete  Edit a command completion [word/pattern/list] •
  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 date/time
  csplit    Split a file into context-determined pieces
  curl      Transfer data  from or to a server
  cut       Divide a file into several parts
  date      Display or change the date & time
  dc        Desk Calculator
  dd        Convert and copy a file, clone disks
  declare   Declare variable & set attributes •
  defaults  Set preferences, show hidden files
  df        Display free disk space
  diff      Display the differences between two files
  diff3     Show differences among three files
  dig       DNS lookup
  dirname   Convert a full pathname to just a path
  dirs      Display list of remembered directories •
  diskutil  Disk utilities - Format, Verify, Repair
  disown    Unbind a job from the current login session •
  ditto     Copy files and folders
  dot_clean Remove dot-underscore files
  drutil    Interact with CD/DVD burners
  dscacheutil  Query or flush the Directory Service/DNS cache
  dseditgroup  Edit, create, manipulate, or delete groups
  dsenableroot Enable root access
  dsmemberutil View user and groups rights
  dscl      Directory Service command line utility
  du        Estimate file space usage
  echo      Display text on screen •
  ed        A line-oriented text editor (edlin)
  enable    Enable and disable builtin shell commands •
  env       List or Set environment variables
  eval      Evaluate several commands/arguments •
  exec      Execute a command •
  exit      Exit the shell •
  expand    Convert tabs to spaces
  expect    Programmed dialogue with interactive programs
            Also see AppleScript
  export    Set an environment variable •
  expr      Evaluate expressions
  false     Do nothing, unsuccessfully
  fc        Fix command (history)
  fdisk     Partition table manipulator for Darwin UFS/HFS/DOS
  fg        Send job to foreground •
  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       Loop command •
  fsck      Filesystem consistency check and repair
  fsaclctl  Filesystem enable/disable ACL support
  fs_usage  Filesystem usage (process/pathname)
  ftp       Internet file transfer program
  function  Define Function Macros
  GetFileInfo Get attributes of HFS+ files
  getopt    Parse positional parameters
  getopts   Parse positional parameters •
  goto      Jump to label and continue execution
  grep      Search file(s) for lines that match a given pattern
  groups    Print group names a user is in
  gzip      Compress or decompress files
  halt      Stop and restart the operating system
  hash      Refresh the cached/remembered location of commands •
  head      Display the first lines of a file
  hdiutil   Manipulate iso disk images
  history   Command History •
  hostname  Print or set system name
  iconv     Convert the character set of a file
  id        Print user and group names/id's
  if        Conditionally perform a command •
  ifconfig  Configure network interface parameters
  ipconfig  View and control IP configuration state
  info      Help info
  install   Copy files and set attributes
  jobs      List active jobs •
  join      Join lines on a common field
  kextfind  List kernel extensions
  kickstart Configure Apple Remote Desktop
  kill      Kill a process by specifying its PID
  killall   Kill processes by name
  l         List files in long format (ls -l)
  last      Indicate last logins of users and ttys
  launchctl Load or unload daemons/agents
  ll        List files in long format, showing invisible files (ls -la)
  less      Display output one screen at a time
  let       Evaluate expression •
  lipo      Convert a universal binary
  ln        Make links between files (hard links, symbolic links)
  local     Set a local (function) variable •
  locate    Find files
  logname   Print current login name
  login     log into the computer
  logout    Exit a login shell (bye) •
  look      Display lines beginning with a given string
  lpr       Print files
  lprm      Remove jobs from the print queue
  lpstat    Printer status information
  ls        List information about file(s)
  lsregister Reset the Launch Services database
  lsbom     List a bill of materials file
  lsof      List open files
  man       Help manual
  mdfind    Spotlight search
  mdutil    Manage Spotlight metadata store
  mkdir     Create new folder(s)
  mkfifo    Make FIFOs (named pipes)
  more      Display output one screen at a time
  mount     Mount a file system
  mv        Move or rename files or directories
  nano      Simple text editor
  net       Manage network resources
  netstat   Show network status
  networksetup Network and System Preferences
  nice      Set the priority of a command
  nohup     Run a command immune to hangups
  ntfs.util NTFS file system utility
  onintr    Control the action of a shell interrupt
  open      Open a file/folder/URL/Application
  opensnoop Snoop file opens as they occur
  osacompile Compile Applescript
  osascript Execute AppleScript
  passwd    Modify a user password
  paste     Merge lines of files
  pbcopy    Copy data to the clipboard
  pbpaste   Paste data from the Clipboard
  ping      Test a network connection
  pkill     Kill processes by a full or partial name
  pkgutil   Query and manipulate installed packages
  plutil    Property list utility
  pmset     Power Management settings
  popd      Restore the previous value of the current directory •
  pr        Convert text files for printing
  printenv  List 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
  rcp       Copy files between machines
  read      Read one line from standard input •
  readonly  Mark a variable or function as read-only •
  reboot    Stop and restart the system
  return    Exit a function •
  rev       Reverse lines of a file
  rm        Remove files
  rmdir     Remove folder(s)
  rpm       Remote Package Manager
  rsync     Remote file copy - Sync file tree
  say       Convert text to audible speech
  screen    Multiplex terminal, run remote shells via ssh
  screencapture Capture screen image to file or disk
  scutil    Manage system configuration parameters
  sdiff     Merge two files interactively
  security  Administer Keychains, keys, certificates and the Security framework
  sed       Stream Editor
  select    Generate a list of items •
  set       Set a shell variable = value •
  setfile   Set attributes of HFS+ files
  shasum    Print or Check SHA Checksums
  shift     Shift positional parameters •
  shopt     Set shell options •
  shutdown  Shutdown or restart OS X
  sips      Scriptable image processing system
  sleep     Delay for a specified time
  softwareupdate System software update tool
  sort      Sort text files
  source    Execute commands from a file •
  split     Split a file into fixed-size pieces
  srm       Securely remove files or directories
  stat      Display the status of a file
  stop      Stop a job or process
  su        Substitute user identity
  sudo      Execute a command as another user
  sum       Print a checksum for a file
  suspend   Suspend execution of this shell •
  sw_vers   Print Mac OS X operating system version
  system_profiler  Report system configuration
  systemsetup Computer and display system settings
  tail      Output the last part of files
  tar       Tape ARchiver
  tcpdump   Dump traffic on a network
  tee       Redirect output to multiple files
  test      Condition evaluation •
  textutil  Manipulate text files in various formats (Doc,html,rtf)
  time      Measure Program Resource Use
  times     Print shell & shell process times •
  tmutil    Time Machine utility
  top       Display process information
  touch     Change file timestamps
  tput      Set terminal-dependent capabilities, color, position
  tr        Translate, squeeze, and/or delete characters
  trap      Execute a command when the shell receives a signal •
  traceroute Trace Route to Host
  true      Do nothing, successfully
  tty       Print filename of terminal on stdin
  type      Describe a command •
  ufs.util  Mount/unmount UFS file system
  ulimit    limit the use of system-wide 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 •
  until     Loop command •
  uptime    Show how long system has been running
  users     Print login names of users currently logged in
  uuencode  Encode a binary file 
  uudecode  Decode a file created by uuencode
  uuidgen   Generate a Unique ID (UUID/GUID)
  uucp      Unix to Unix copy
  vi        Text Editor
  wait      Wait for a process to complete •
  wc        Print byte, word, and line counts
  whatis    Search the whatis database for complete words
  whereis   Locate a program
  which     Locate a program file in the user's path
  while     Loop command •
  who       Print all usernames currently logged on
  whoami    Print the current user id and name (`id -un')
  write     Send a message to another user
  xargs     Execute utility - passing arguments
  xattr     Display and manipulate extended attributes
 youtube-dl Download video
  yes       Print a string until interrupted
  zip       Package and compress (archive) files.
  !!        Run the last command again

Apple OS X command line

How to Diskpart Erase or Clean a Drive

How to Diskpart Erase or Clean a Drive Through the Command Prompt

How to Diskpart Erase or Clean a Drive


Critical Instructions:

  • Disclaimer: Seagate Technology, LLC is not responsible for lost user data. Be sure to back up any important data on this drive before proceeding.
  • This article explains the Microsoft Diskpart Erase utility. The command that erases the drive during this process is “Clean”. In this article “Clean” and erase are used interchangeably. Cleaning or erasing a storage device removes all data and partitions from the drive.
  • Please read all steps, instructions, and warnings before attempting the Diskpart Erase/Clean. 
  • Diskpart Erase/Clean will permanently erase/destroy all data on the selected drive. Please make certain that you are erasing the correct disk.
  • Remove all additional drives from the computer excluding the drive you are booting from and the drive you want to Erase/Clean.
  • For more information regarding Microsoft’s Diskpart Utility please select here:

Items to note:

  • This article will walk through the steps of using the Microsoft Diskpart Erase utility to Clean the disk of a previous partition and format, including any data on the drive. This command takes only a few minutes to complete.
  • This article covers Diskpart Erasing a 3TB or larger drive that has a Master Boot Record (MBR) Partition table, which is thereby limiting its capacity to 2TB. However, this article also applies to any scenario where a Diskpart Erase of an entire disk is necessary.
  • For more information regarding drives over 2TB and GPT/MBR partition tables please see the following articles.
  1. To determine the disk number assigned to the 3TB+ MBR partitioned drive follow the steps below.
    1. From the Start menu right click on Computer which will provide a drop down menu. (If you are on Windows 8 or 8.1 move your mouse to the bottom left hand corner of the desktop screen and right click. Then select Disk Management).
    2. Choose Manage.
    3. Select Disk Management (listed under Storage).
    4. Look for the drive that is identified as the 3TB drive (2794GB). The properties window shows that the partition table on the drive is MBR . Important: note the Disk number (such as Disk 1).
      Shows disk management with a properties box open. Disk 1 is squared off and there is an arrow pointing to "2048GB Unallocated" and Master Boot Record
  2. Open a Command Prompt window. To open the Command Prompt on a Windows Vista or Windows 7 machine click on Start and type cmd in the search bar. Then right click on cmd.exe and run as administrator. It will prompt you with the message, “Do you want to allow the following program to make changes to this computer,” click yes. A black Command Prompt window will open.
    Shows how to search for CMD from the Start Menu. There is an arrow pointing to the text cmd and the application cmd.exeOn Windows 8 move your mouse to the bottom left hand corner of the desktop screen and right click. Select Command Prompt (Admin) from the pop-up menu.
    Shows the pop up window from Windows 8. The Compand Prompt (Admin) is highlighted. There is an arrow pointing to Command Prompt (Admin)This is the Command Prompt window.
    Shows the command prompt window C:\Windows\system32>_ is the bottom line.
  3. From the command prompt, type diskpart and press Enter.
    Shows the command prompt window shows that I have typed "diskpart"The diskpart prompt will open.
    Shows the command prompt window that DISKPART> is now the selected command
  4. From the diskpart prompt, type list disk and press Enter.
    Shows the command prompt window and that I have typed "list disk"A list of disks will appear in a text format. You will return to the diskpart prompt. Step one verified that Disk 1 is the 3TB drive.Warning: Diskpart Erase/Clean will permanently erase/destroy all data on the selected drive. Please be certain that you are erasing the correct disk. "Shows the command prompt window and displays all detected disks. Disk 1 is squared off. "
  5. From the diskpart prompt you will need to select a disk disk number (for instance, if the 3TB+ drive is Disk 1, you would typeselect disk 1) and press Enter. Warning: Diskpart Erase/Clean will permanently erase/destroy all data on the selected drive. Please be certain that you are erasing the correct disk.
    Shows the command prompt window and that I have typed "select disk 1"A message appears saying that the disk is selected. You will return to the diskpart prompt. Warning: Diskpart Erase/Clean will permanently erase/destroy all data on the selected drive. Please be certain that you are erasing the correct disk.
    "Shows the command prompt window and displays that Disk 1 is now the selected disk "
  6. From the diskpart prompt, type clean and press Enter. The drive’s partition, data, and signature is now removed. You will return to the diskpart prompt. Warning: Once you type clean and hit enter the drive will be erased. No warning will be provided.
    Shows the command prompt window and that I have typed "clean"
  7. The Command Prompt window will display the message “DiskPart succeeded in cleaning the disk“.  Close out of the Command Prompt window by clicking the red X in the upper right hand corner.
    Shows the command prompt window and displays DiskPart succeeded in cleaning the disk. DiskPart succeeded in cleaning the disk is squared off.Now the 3TB+ drive can be re-initialized, partitioned, and formatted.
  8. Reference How to use Add a New Disk/Reformat in Windows using DiscWizard v16 to Initialize the drive in GPT and format the drive for use.

How to Diskpart Erase or Clean a Drive

Format a hard drive with Command Prompt

Format a hard drive with Command Prompt

Format a hard drive with Command Prompt


In Windows I would normally be driven to either format a drive through the Disk Management console or by right-clicking on a drive in Windows Explorer and selecting the “Format…” option, but there can be advantages to formatting a driver through Command Prompt. For example if you are reformatting a drive which previously had an Operating System on the drive you can find there are System Partitions on the drive which can’t be seen in Windows Explorer and refuse to format in the Disk Management console.

Note this is only a quick guide for Formatting Drives from Command Line, there are many more options available at your disposal. For a detailed insight to the options available for the DiskPart tool visit Microsofts Technet. In the example I have formatted an external hard drive for use of file storage in a Windows Operating System environment.

In order to format a drive through Command Prompt firstly lets open the prompt.

Click Start > Run and type “CMD”, pressing Enter should open a new terminal.

Start CMD


We need to next start the Disk Part tool, type “DISK PART” into the Command Line and press Enter.

Start Disk Part


Next let’s display and identify which volume we would like to format. Type “list volume” and press Enter. You should see a list of available volumes. Identify the one which you wish to format, be careful selecting the wrong volume will spell disaster!

List Volume


Type “select volume <x>” and press Enter, where <x> is the volume you wish to focus on.

Select Volume


Type “clean” and press Enter. This removes any and all partition or volume formatting from the disk in focus.



Type “create partition primary” and press Enter. This creates a primary partition on the current disk. After you create the partition, the focus automatically shifts to the new partition. It is possible to create multiple partitions if you like. To do this you would add the option size=<x> where <x> is the size in megabytes (MB) you would like the partition to be. If no size is specified, like in my example, the partition continues until there is no more unallocated space.

Create Partition


Type “format fs=ntfs quick label=test” and press Enter. This will now perform a quick format, using a ntfs file system and labelling the drive “test”. You may wish to use the file system fat32 in place of ntfs if you would like to use the drive with other operating systems.



Lastly type “assign letter <x>” and press Enter, where <x> is the letter you would like to assign the drive.

Assign Drive Letter

You can close the Disk Part tool and Command Prompt using the “exit” command. You should now see your freshly formatted drive in My Computer, ready to use.



Format a hard drive with Command Prompt


Format a hard drive with Command Prompt

Record Your iPhone or iPad Screen with QuickTime

Record Your iPhone or iPad Screen with QuickTime

The ability to record an iPhone or iPad screen has long been available, but it required some work to get it going, such as jailbreak-only apps or AirPlay. With OS X Yosemite and iOS 8, Apple has now made recording the iPhone or iPad an easy and simple task. The key is QuickTime.

Launch QuickTime and select File > New Movie Recording from the menu bar. Alternatively, you can use the keyboard shortcut Option-Command-N. This will launch a new QuickTime window for video recording. By default, QuickTime will activate your Mac’s built-in iSight camera, but ignore that and find and click on the small downward-facing triangle next to the record button. This lets you select an alternate recording source, which now includes your iPhone or iPad.







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