NAME¶
sighold
,
sigignore
,
sigpause
,
sigrelse
,
sigset
—
legacy interface for signal management
LIBRARY¶
Standard C Library (libc, -lc)
SYNOPSIS¶
#include
<signal.h>
int
sighold
(
int
sig);
int
sigignore
(
int
sig);
int
xsi_sigpause
(
int
sigmask);
int
sigrelse
(
int
sig);
void (*)(int)
sigset
(
int,
void
(*disp)(int));
int
sigpause
(
int
sigmask);
DESCRIPTION¶
This interface is made obsolete by
sigsuspend(2) and
sigaction(2).
The
sigset
() function modifies signal
dispositions. The
sig argument specifies the
signal, which may be any signal except
SIGKILL
and
SIGSTOP
. The
disp argument specifies the signal's
disposition, which may be
SIG_DFL
,
SIG_IGN
, or the address of a signal
handler. If
sigset
() is used, and
disp is the address of a signal handler, the
system adds
sig to the signal mask of the
calling process before executing the signal handler; when the signal handler
returns, the system restores the signal mask of the calling process to its
state prior to the delivery of the signal. In addition, if
sigset
() is used, and
disp is equal to
SIG_HOLD
,
sig is added to the signal mask of the
calling process and
sig 's disposition
remains unchanged. If
sigset
() is used, and
disp is not equal to
SIG_HOLD
,
sig is removed from the signal mask of the
calling process.
The
sighold
() function adds
sig to the signal mask of the calling
process.
The
sigrelse
() function removes
sig from the signal mask of the calling
process.
The
sigignore
() function sets the disposition
of
sig to
SIG_IGN
.
The
xsi_sigpause
() function removes
sig from the signal mask of the calling
process and suspend the calling process until a signal is received. The
xsi_sigpause
() function restores the signal
mask of the process to its original state before returning.
The
sigpause
() function assigns
sigmask to the set of masked signals and then
waits for a signal to arrive; on return the set of masked signals is restored.
The
sigmask argument is usually 0 to indicate
that no signals are to be blocked.
RETURN VALUES¶
The
sigpause
() and
xsi_sigpause
() functions always terminate
by being interrupted, returning -1 with
errno
set to
EINTR
.
Upon successful completion,
sigset
() returns
SIG_HOLD
if the signal had been blocked and
the signal's previous disposition if it had not been blocked. Otherwise,
SIG_ERR
is returned and
errno set to indicate the error.
For all other functions, upon successful completion, 0 is returned. Otherwise,
-1 is returned and
errno is set to indicate
the error:
- [
EINVAL
]
- The sig argument is not a valid signal
number.
- [
EINVAL
]
- For
sigset
() and
sigignore
() functions, an attempt was
made to catch or ignore SIGKILL
or
SIGSTOP
.
SEE ALSO¶
kill(2),
sigaction(2),
sigblock(2),
sigprocmask(2),
sigsuspend(2),
sigvec(2)
STANDARDS¶
The
sigpause
() function is implemented for
compatibility with historic
4.3BSD applications. An
incompatible interface by the same name, which used a single signal number
rather than a mask, was present in
AT&T System V
UNIX, and was copied from there into the
X/Open System Interfaces (XSI) option of
IEEE Std 1003.1-2001
(“POSIX.1”).
FreeBSD implements
it under the name
xsi_sigpause
(). The
sighold
(),
sigignore
(),
sigrelse
() and
sigset
() functions are implemented for
compatibility with
System V and
XSI interfaces.
HISTORY¶
The
sigpause
() function appeared in
4.2BSD and has been deprecated. All other functions
appeared in
FreeBSD 8.1 and were deprecated before
being implemented.