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NAME

wait.h, wait - wait status

SYNOPSIS

#include <sys/wait.h>

DESCRIPTION

When a process waits for status from its children using either the
wait(3C) or waitpid(3C) function, the status returned can be
evaluated with the following macros, defined in <sys/wait.h>. These
macros evaluate to integral expressions. The stat argument to these
macros is the integer value returned from wait() or waitpid().

WCOREDUMP(stat)
If the value of WIFSIGNALED (stat) is non-zero,
this macro evaluates to a non-zero value if a
core image of the terminated child was created.


WEXITSTATUS(stat)
If the value of WIFEXITED(stat) is non-zero,
this macro evaluates to the exit code that the
child process passed to _exit() (see exit(2))
or exit(3C), or the value that the child
process returned from main.


WIFCONTINUED(stat)
Evaluates to a non-zero value if status was
returned for a child process that has
continued.


WIFEXITED(stat)
Evaluates to a non-zero value if status was
returned for a child process that terminated
normally.


WIFSIGNALED(stat)
Evaluates to a non-zero value if status was
returned for a child process that terminated
due to the receipt of a signal.


WIFSTOPPED(stat)
Evaluates to a non-zero value if status was
returned for a child process that is currently
stopped.


WSTOPSIG(stat)
If the value of WIFSTOPPED(stat) is non-zero,
this macro evaluates to the number of the
signal that caused the child process to stop.


WTERMSIG(stat)
If the value of WIFSIGNALED(stat) is non-zero,
this macro evaluates to the number of the
signal that caused the termination of the child
process.


The <sys/wait.h> header defines the symbolic constants listed below
for use with waitpid(3C).

WNOHANG
Do not hang if no status is available; return
immediately.


WUNTRACED
Report status of stopped child process.


The symbolic constants listed below are defined as possible values
for the options argument to waitid(2).

WEXITED
Wait for processes that have exited.


WSTOPPED
Status is returned for any child that has stopped upon
receipt of a signal.


WCONTINUED
Status is returned for any child that was stopped and
has been continued.


WNOHANG
Return immediately if there are no children to wait
for.


WNOWAIT
Keep the process whose status is returned in infop in a
waitable state.


The type idtype_t is defined as an enumeration type whose possible
values include the following:

P_ALL
P_PID
P_PGID


The id_t and pid_t types are defined as described in <sys/types.h>.


The siginfo_t type is defined as described in <signal.h>.


The rusage structure is defined as described in <sys/resource.h>.


Inclusion of the <sys/wait.h> header can also make visible all
symbols from <signal.h> and <sys/resource.h>.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+

SEE ALSO

exit(2), waitid(2), exit(3C), wait(3C), waitpid(3C), attributes(7),
standards(7)

September 10, 2004 WAIT.H(3HEAD)