suspend [-f]
Suspend the execution of this shell until it receives a SIGCONT signal.
If the -f option is given, do not complain about this being a login shell; just suspend anyway.
In this implementation, suspend returns a control flow signal that tells the session/executor to pause execution. The session should wait for a resume message before continuing.
Exit Status: Returns success unless job control is not enabled or an error occurs.
Reference: https://cgit.git.savannah.gnu.org/cgit/bash.git/plain/builtins/suspend.def?h=bash-5.3