Multiple choice unix

Which of the following special shell variables is used to process number of the last background job?

  1. $!

  2. $#

  3. $0

  4. $*

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$! contains the process ID (PID) of the last background job. $# counts positional parameters, $0 is the script name, $* references all parameters as a single string.