HP-UX Reference (11i v3 07/02) - 2 System Calls (vol 5)

w
wait(2) wait(2)
HP-UX EXTENSION: If and only if this flag is set,
waitpid() or wait3() (see
wait3(2)) returns information on child or attached processes that are stopped because
they received a
SIGTTIN, SIGTTOU, SIGTSTP
or SIGSTOP signal, and whose
status has not yet been reported. Regardless of this flag, status is returned for child
or attached processes that have terminated or are stopped and traced and whose
status has not yet been reported.
If the calling process has the signal action
SA_NOCLDWAIT set or has SIGCHLD set to SIG_IGN, and the
process has no unwaited-for children that were transformed into zombie processes, the calling thread blocks
until all of the children of the process containing the calling thread terminate, and
wait() and wait-
pid()
fail and set errno to [ECHILD].
If wait() or waitpid() return because the status of a child process is available, these functions return
a value equal to the process ID of the child process. In this case, if the value of the argument stat_loc is not
a null pointer, information is stored in the location pointed to by stat_loc . The value stored at the location
pointed to by stat_loc is 0 if and only if the status returned is from a terminated child process that ter-
minated by one of the following means:
1. The process returned 0 from main().
2. The process called _exit() or exit() with a status argument of 0.
3. The process was terminated because the last thread in the process terminated.
Previous versions of HP-UX documented the bit encodings of the status returned by
wait() which could
be interpreted directly and applications doing this will continue to work correctly. However, new applica-
tions should use the provided status interpretation macros shown below for maximum portability.
Status Interpretation Macros
Regardless of its value, this information may be interpreted using the following macros, which are defined
in
<sys/wait.h> and evaluate to integral expressions; the stat_val argument is the integer value
pointed to by stat_loc .
WCOREDUMP( stat_val) HP-UX EXTENSION: If the value of WIFSIGNALED( stat_val ) is
nonzero, this macro evaluates to a nonzero value if a "core image"
dump was produced (see signal(5)).
WEXITSTATUS( stat_val ) If the value of WIFEXITED(stat_val ) is nonzero, this macro evalu-
ates to the low-order 8 bits of the status argument that the child pro-
cess passed to _exit() or exit() or the value the child process
returned from main().
WIFCONTINUED(stat_val) Evaluates to a nonzero value if status was returned for a child process
that has continued from a job control stop.
WIFEXITED( stat_val) Evaluates to a nonzero value if status was reported for a child process
that terminated normally.
WIFSIGNALED( stat_val ) Evaluates to a nonzero value if status was reported for a child process
that terminated due to the receipt of a signal that was not caught (see
<signal.h> ).
WIFSTOPPED( stat_val) Evaluates to a nonzero value if status was reported for a child process
that is currently stopped.
WSTOPSIG(stat_val ) If the value of WIFSTOPPED( stat_val ) is nonzero, this macro evalu-
ates to the number of the signal that caused the child process to stop.
WTERMSIG(stat_val ) If the value of WIFSIGNALED( stat_val) is nonzero, this macro
evaluates to the number of the signal that caused the termination of
the child process.
If the information pointed to by stat_loc was stored by a call to waitpid() that specified the WUN-
TRACED
flag and did not specify the WCONTINUED flag, exactly one of the macros
WIFEXITED(* stat_loc), WIFSIGNALED(*stat_loc ), and WIFSTOPPED(* stat_loc ) evaluates to a
nonzero value.
HP-UX 11i Version 3: February 2007 − 2 − Hewlett-Packard Company 543