waitid(2)waitid(2)NAMEwaitid - wait for child process to change state
The function suspends the calling process until one of its children
changes state. It records the current state of a child in the structure
pointed to by infop. If a child process changed state prior to the
call to returns immediately.
The idtype and id arguments are used to specify which children will
If idtype is will wait for the child with a process ID equal to
If idtypeis will wait for any child with a process group ID equal to
If idtypeis will wait for any children and id is ignored.
The options argument is used to specify which state changes will wait
for. It is formed by OR-ing together one or more of the following
Wait for processes that have exited.
Status will be returned for any child that has stopped upon
of a signal.
Status will be returned for any child that was stopped and has
Return immediately if there are no children to wait for.
Keep the process whose status is returned in
infop in a waitable state. This will
not affect the state of the process;
the process may be waited for again
after this call completes.
The infop argument must point to a structure. If returns because a
child process was found that satisfied the conditions indicated by the
arguments idtype and options, then the structure pointed to by infop
will be filled in by the system with the status of the process. The
si_signo member will always be equal to
If returns due to the change of state of one of its children, 0 is
returned. Otherwise, −1 is returned and is set to indicate the error.
The function will fail if:
[ECHILD] The calling process has no existing unwaited-for
[EINTR] The function was interrupted due to the receipt
of a signal by the calling process.
[EINVAL] An invalid value was specified for options, or
idtype and id specify an invalid set of pro‐
In a multi-threaded application, only the calling thread is suspended
will not return until all threads in the process have reached the
desired state. For example, if the or options are specified, will not
return until all threads in the process have terminated, stopped or
SEE ALSOexec(2), exit(2), wait(2), <sys/wait.h>.
First released in Issue 4, Version 2.