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(5) for descriptions of the following attributes:

See Also

exit(2), waitid(2), exit(3C), wait(3C), waitpid(3C),attributes(5), standards(5)