waitpid(2) - man - phpman

Wait for the termination of arbitrary processes.

• Sleep until all processes whose PIDs have been specified have exited
  waitpid {{pid1 pid2 ...}}
• Sleep for at most `n` seconds
  waitpid {{-t|--timeout}} {{n}} {{pid1 pid2 ...}}
• Do not error if specified PIDs have already exited
  waitpid {{-e|--exited}} {{pid1 pid2 ...}}
• Sleep until `n` of the specified processes have exited
  waitpid {{-c|--count}} {{n}} {{pid1 pid2 ...}}
• Display help
  waitpid {{-h|--help}}