WAIT(2) System Calls Manual WAIT(2)
wait - wait for process to terminate
Wait causes its caller to delay until a signal is received or one of
its child processes terminates. If any child has died since the last
wait, return is immediate; if there are no children, return is immedi-
ate with the error bit set (resp. with a value of -1 returned). The
normal return yields the process ID of the terminated child. In the
case of several children several wait calls are needed to learn of all
If (int)status is nonzero, the high byte of the word pointed to
receives the low byte of the argument of exit when the child termi-
nated. The low byte receives the termination status of the process.
See signal(2) for a list of termination statuses (signals); 0 status
indicates normal termination. A special status (0177) is returned for
a stopped process which has not terminated and can be restarted. See
ptrace(2). If the 0200 bit of the termination status is set, a core
image of the process was produced by the system.
If the parent process terminates without waiting on its children, the
initialization process (process ID = 1) inherits the children.
exit(2), fork(2), signal(2)
Returns -1 if there are no children not previously waited for.
(wait = 7.)
(process ID in r0)
(status in r1)
The high byte of the status is the low byte of r0 in the child at ter-