wait.h File Reference

Event management functions. More...

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Macros
#define	WNOHANG   0x00000001
	Return immediately if no child is there to be waited for.
#define	WUNTRACED   0x00000002
	Return for children that are stopped, and whose status has not been reported.
#define	WIFSIGNALED(status)   (!WIFSTOPPED(status) && !WIFEXITED(status))
	returns true if the child process exited because of a signal that was not caught.
#define	WIFSTOPPED(status)   (((status)&0xff) == 0x7f)
	returns true if the child process that caused the return is currently stopped; this is only possible if the call was done using WUNTRACED().
#define	WEXITSTATUS(status)   (((status)&0xff00) >> 8)
	evaluates to the least significant eight bits of the return code of the child that terminated, which may have been set as the argument to a call to exit() or as the argument for a return statement in the main program. This macro can only be evaluated if WIFEXITED() returned nonzero.
#define	WTERMSIG(status)   ((status)&0x7f)
	returns the number of the signal that caused the child process to terminate. This macro can only be evaluated if WIFSIGNALED() returned nonzero.
#define	WIFEXITED(status)   (WTERMSIG(status) == 0)
	Is nonzero if the child exited normally.
#define	WSTOPSIG(status)   (WEXITSTATUS(status))
	returns the number of the signal that caused the child to stop. This macro can only be evaluated if WIFSTOPPED() returned nonzero.
#define	TASK_RUNNING   0x00
	The process is either: 1) running on CPU or 2) waiting in a run queue.
#define	TASK_INTERRUPTIBLE   (1 << 0)
	The process is sleeping, waiting for some event to occur.
#define	TASK_UNINTERRUPTIBLE   (1 << 1)
	Similar to TASK_INTERRUPTIBLE, but it doesn't process signals.
#define	TASK_STOPPED   (1 << 2)
	Stopped, it's not running, and not able to run.
#define	TASK_TRACED   (1 << 3)
	Is being monitored by other processes such as debuggers.
#define	EXIT_ZOMBIE   (1 << 4)
	The process has terminated.
#define	EXIT_DEAD   (1 << 5)
	The final state.

Functions
pid_t	wait (int *status)
	Suspends the execution of the calling thread until ANY child has changed state. More...
pid_t	waitpid (pid_t pid, int *status, int options)
	Suspends the execution of the calling thread until a child specified by pid argument has changed state. More...

Detailed Description

Event management functions.

Copyright

(c) 2014-2024 This file is distributed under the MIT License. See LICENSE.md for details.

Function Documentation

wait()

pid_t wait

(

int *

status

)

Suspends the execution of the calling thread until ANY child has changed state.

Parameters

status

Variable where the new status of the child is stored.

Returns

On error, -1 is returned, otherwise it returns the pid of the child that has unlocked the wait.

waitpid()

pid_t waitpid	(	pid_t	pid,
		int *	status,
		int	options
	)

Suspends the execution of the calling thread until a child specified by pid argument has changed state.

Parameters

pid	Se details below for more information.
status	Variable where the new status of the child is stored.
options	Waitpid options.

Returns

On error, -1 is returned, otherwise it returns the pid of the child that has unlocked the wait.

By default, waitpid() waits only for terminated children, but this behavior is modifiable via the options argument, as described below. The value of pid can be:

• 1 meaning wait for any child process. 0 meaning wait for any child process whose process group ID is equal to that of the calling process. > 0 meaning wait for the child whose process ID is equal to the value of pid.