Alias Facts

Aliases in Linux

Definition

• An alias is a shortcut stored in memory that runs a command on your Linux system.

• Most distributions include predefined aliases created at system startup.

• Custom aliases can be defined in the shell prompt.

Persistence of Aliases

• Aliases defined with the alias command are not persistent across reboots.

• To make aliases persistent, add definitions to:

  • /etc/profile

  • ~/.bashrc

Displaying Defined Aliases

• Use the command alias to display currently defined aliases.

  • Example output:

    • alias egrep='egrep --color=auto'

    • alias fgrep='fgrep --color=auto'

    • alias grep='grep --color=auto'

    • alias ll='ls -l --color=auto'

    • alias ls='ls --color=auto'

Creating and Removing Aliases

Creating Aliases

• Command format: alias [name='command']

• Example:

  • alias securebackup='cp ./*.* /dev/st0/*.*; shred -fuvz ./*'

    • Description: Copies all files in the specified directory to a tape backup device and shreds the original files.

  • A single alias can run multiple commands; encapsulate commands with quotation marks or apostrophes.

Removing Aliases

• Command format: unalias [name]

• Example: unalias securebackup

  • Description: Removes the specified alias.

  • Example: unalias forcelogout to delete the forcelogout alias.