chickadee » scsh-process » wait

wait #!optional pid-or-process nohangprocedure

Like process-wait: Suspends the current process until the child process described by pid-or-process (either a numerical process ID or a scsh-process object) has terminated using the UNIX system call waitpid(). If pid-or-process is not given, then this procedure waits for any child process. If nohang is given and not #f then the current process is not suspended.

This procedure returns three values, in a different order from process-wait:

  • Either the exit status, if the process terminated normally or the signal number that terminated/stopped the process.
  • #t if the process exited normally or #f otherwise.
  • pid or 0

All values are #f, if nohang is true and the child process has not terminated yet.

It is allowed to wait multiple times for the same process after it has completed, if you pass a process object. Process IDs can only be waited for once after they have completed and will cause an error otherwise.