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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)