Multiple choice technology

Command to retrieve the Process ID of current process

  1. $$
  2. $?
  3. $!
  4. $#
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A Correct answer
Explanation

$$ expands to the process ID (PID) of the current shell. This is useful for creating unique temporary filenames or tracking the shell process. $? is exit status, $! is last background job PID, $# is argument count.