What is the Difference Between $SHELL and $0 Environment Variables?

Both $SHELL and $0 are environment variables that provide information related to the shell in Unix or Unix-like operating systems, but they differ in the following ways.

$SHELL

• This environment variable stores the path to the default shell for the logged-in user.
• Example:

  $ echo $SHELL
  /bin/bash
  
  $ sh
  sh-3.2 $ echo $SHELL
  /bin/bash

  In the above example, irrespective of the shell that you are currently using, $SHELL will give you the default shell path set for the active user.

$0

• This environment variable provides the name of the current shell when used on any interactive shell prompt. Note that if used within a script, it will give you the name of the script being executed.
• Example:

  $ echo $0
  bash
  
  $ zsh
  % echo $0
  zsh

  In the above example, you get the name of the current shell when $0 is echoed.

This is not an AI-generated article but is demonstrated by a human.

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