POSIX Signals option group. More...

Files
file	string.h
	<string.h>: POSIX extensions to the C string library

Functions
int	kill (pid_t pid, int sig)
	Send a signal to a process or process group.

int	killpg (pid_t pgrp, int sig)
	Send a signal to a process group (XSI extension).

void	psiginfo (const siginfo_t info, const char message)
	Print a signal description with additional siginfo_t context.

void	psignal (int sig, const char *message)
	Print a signal description to stderr.

int	sigaction (int sig, const struct sigaction ZRESTRICT act, struct sigaction ZRESTRICT oact)
	Examine and change a signal action.

int	sigaddset (sigset_t *set, int sig)
	Add a signal to a signal set.

int	sigaltstack (const stack_t ZRESTRICT ss, stack_t ZRESTRICT oss)
	Set or get the alternate signal stack (XSI extension).

int	sigdelset (sigset_t *set, int sig)
	Delete a signal from a signal set.

int	sigemptyset (sigset_t *set)
	Initialise a signal set to the empty set.

int	sigfillset (sigset_t *set)
	Initialise a signal set to the full set (all signals).

int	sighold (int sig)
	Add a signal to the calling process's signal mask (XSI, obsolescent).

int	sigignore (int sig)
	Set a signal's disposition to SIG_IGN (XSI, obsolescent).

int	siginterrupt (int sig, int flag)
	Control whether a signal restarts or interrupts system calls (XSI, obsolescent).

int	sigismember (const sigset_t *set, int sig)
	Test whether a signal is a member of a signal set.

int	sigpause (int sig)
	Suspend execution until a signal is delivered (XSI, obsolescent).

int	sigpending (sigset_t *set)
	Retrieve the set of pending signals.

int	sigprocmask (int how, const sigset_t ZRESTRICT set, sigset_t ZRESTRICT oset)
	Examine and change the calling process's signal mask.

int	sigrelse (int sig)
	Remove a signal from the process signal mask (XSI, obsolescent).

sighandler_t	sigset (int sig, sighandler_t disp)
	Set the disposition of a signal, optionally blocking it first (XSI, obsolescent).

int	sigsuspend (const sigset_t *set)
	Wait for a signal, atomically replacing the process signal mask.

int	sigwait (const sigset_t ZRESTRICT set, int ZRESTRICT sig)
	Wait for a signal from a set.

char *	strsignal (int signo)
	Return a string describing a signal number.

unsigned int	alarm (unsigned int seconds)
	Schedule an alarm signal (SIGALRM) after a given number of seconds.

int	pause (void)
	Suspend process execution until a signal is received.

Detailed Description

POSIX Signals option group.

Covers alarm(), pause(), kill(), sigaction(), sigprocmask(), sigsuspend(), sigpending(), and related signal-handling functions.

Function Documentation

◆ alarm()

unsigned int alarm ( unsigned int seconds )

Schedule an alarm signal (SIGALRM) after a given number of seconds.

◆ kill()

int kill	(	pid_t	pid,
		int	sig
	)

Send a signal to a process or process group.

Parameters

pid	Target process ID (positive), process group (negative), or 0.
sig	Signal number, or 0 to check process existence.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/kill.html

◆ killpg()

int killpg	(	pid_t	pgrp,
		int	sig
	)

Send a signal to a process group (XSI extension).

Parameters

pgrp	Process group ID (0 = calling process's group).
sig	Signal number.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/killpg.html

◆ pause()

int pause ( void )

Suspend process execution until a signal is received.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/pause.html

◆ psiginfo()

void psiginfo	(	const siginfo_t *	info,
		const char *	message
	)

Print a signal description with additional siginfo_t context.

Parameters

info	Signal information.
message	Prefix string.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/psiginfo.html

◆ psignal()

void psignal	(	int	sig,
		const char *	message
	)

Print a signal description to stderr.

Parameters

sig	Signal number.
message	Prefix string.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/psignal.html

◆ sigaction()

int sigaction	(	int	sig,
		const struct sigaction *ZRESTRICT	act,
		struct sigaction *ZRESTRICT	oact
	)

Examine and change a signal action.

Parameters

sig	Signal number.
act	New action, or NULL to query.
oact	Output: previous action, or NULL.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigaction.html

◆ sigaddset()

int sigaddset	(	sigset_t *	set,
		int	sig
	)

Add a signal to a signal set.

Parameters

set	Signal set.
sig	Signal number to add.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigaddset.html

◆ sigaltstack()

int sigaltstack	(	const stack_t *ZRESTRICT	ss,
		stack_t *ZRESTRICT	oss
	)

Set or get the alternate signal stack (XSI extension).

Parameters

ss	New alternate stack descriptor, or NULL.
oss	Output: previous descriptor, or NULL.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigaltstack.html

◆ sigdelset()

int sigdelset	(	sigset_t *	set,
		int	sig
	)

Delete a signal from a signal set.

Parameters

set	Signal set.
sig	Signal number to remove.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigdelset.html

◆ sigemptyset()

int sigemptyset ( sigset_t * set )

Initialise a signal set to the empty set.

Parameters

set	Signal set to clear.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigemptyset.html

◆ sigfillset()

int sigfillset ( sigset_t * set )

Initialise a signal set to the full set (all signals).

Parameters

set	Signal set to fill.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigfillset.html

◆ sighold()

int sighold ( int sig )

Add a signal to the calling process's signal mask (XSI, obsolescent).

Parameters

sig	Signal to block.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sighold.html

◆ sigignore()

int sigignore ( int sig )

Set a signal's disposition to SIG_IGN (XSI, obsolescent).

Parameters

sig	Signal to ignore.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigignore.html

◆ siginterrupt()

int siginterrupt	(	int	sig,
		int	flag
	)

Control whether a signal restarts or interrupts system calls (XSI, obsolescent).

Parameters

sig	Signal number.
flag	Non-zero to interrupt; 0 to restart.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/siginterrupt.html

◆ sigismember()

int sigismember	(	const sigset_t *	set,
		int	sig
	)

Test whether a signal is a member of a signal set.

Parameters

set	Signal set to query.
sig	Signal number to test.

Returns: 1 if the signal is a member, 0 if not, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigismember.html

◆ sigpause()

int sigpause ( int sig )

Suspend execution until a signal is delivered (XSI, obsolescent).

Parameters

sig	Signal whose blocking is temporarily removed.

Returns: Always returns -1 with errno set to EINTR.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigpause.html

◆ sigpending()

int sigpending ( sigset_t * set )

Retrieve the set of pending signals.

Parameters

set	Output: set of signals pending delivery to the calling process.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigpending.html

◆ sigprocmask()

int sigprocmask	(	int	how,
		const sigset_t *ZRESTRICT	set,
		sigset_t *ZRESTRICT	oset
	)

Examine and change the calling process's signal mask.

Parameters

how	`SIG_BLOCK`, `SIG_UNBLOCK`, or `SIG_SETMASK`.
set	Signal set to apply, or NULL.
oset	Output: previous mask, or NULL.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigprocmask.html

◆ sigrelse()

int sigrelse ( int sig )

Remove a signal from the process signal mask (XSI, obsolescent).

Parameters

sig	Signal to unblock.

Returns: 0 on success, or -1 with errno set on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigrelse.html

◆ sigset()

sighandler_t sigset	(	int	sig,
		sighandler_t	disp
	)

Set the disposition of a signal, optionally blocking it first (XSI, obsolescent).

Parameters

sig	Signal number.
disp	New disposition (SIG_DFL, SIG_IGN, SIG_HOLD, or a handler).

Returns: Previous disposition on success, or SIG_ERR on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigset.html

◆ sigsuspend()

int sigsuspend ( const sigset_t * set )

Wait for a signal, atomically replacing the process signal mask.

Parameters

set	New signal mask to apply while waiting.

Returns: Always returns -1 with errno set to EINTR.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigsuspend.html

◆ sigwait()

int sigwait	(	const sigset_t *ZRESTRICT	set,
		int *ZRESTRICT	sig
	)

Wait for a signal from a set.

Parameters

set	Output signal set to wait on.
sig	Output: number of the accepted signal.

Returns: 0 on success, or a positive error number on failure.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigwait.html

◆ strsignal()

char * strsignal ( int signo )

Return a string describing a signal number.

Returns a pointer to a locale-specific message string describing the signal whose number is signo. The contents of the string pointed to by the return value must not be modified by the application. The returned pointer may be invalidated by a subsequent call to strsignal().

Parameters

signo Signal number.

Returns: Pointer to a string describing the signal, or an unspecified string if signo is an unknown signal number.

See also: https://pubs.opengroup.org/onlinepubs/9699919799/functions/strsignal.html

Files

Functions

Detailed Description

Function Documentation

◆ alarm()

◆ kill()

◆ killpg()

◆ pause()

◆ psiginfo()

◆ psignal()

◆ sigaction()

◆ sigaddset()

◆ sigaltstack()

◆ sigdelset()

◆ sigemptyset()

◆ sigfillset()

◆ sighold()

◆ sigignore()

◆ siginterrupt()

◆ sigismember()

◆ sigpause()

◆ sigpending()

◆ sigprocmask()

◆ sigrelse()

◆ sigset()

◆ sigsuspend()

◆ sigwait()

◆ strsignal()