sigset, sighold, sigrelse, sigignore - System V signal API
#include <signal.h>
typedef void (*sighandler_t)(int);
[[deprecated]] sighandler_t sigset(int sig, sighandler_t disp);
[[deprecated]] int sighold(int sig);
[[deprecated]] int sigrelse(int sig);
[[deprecated]] int sigignore(int sig);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
These functions are provided in glibc as a compatibility interface for programs that make use of the historical System V signal API. This API is obsolete: new applications should use the POSIX signal API (sigaction(2), sigprocmask(2), etc.)
The sigset() function modifies the disposition of
the signal sig
. The disp
argument can be the address
of a signal handler function, or one of the following constants:
Reset the disposition of sig
to the default.
Ignore sig
.
Add sig
to the process's signal mask, but leave the
disposition of sig
unchanged.
If disp
specifies the address of a signal handler, then
sig
is added to the process's signal mask during execution of
the handler.
If disp
was specified as a value other than
SIG_HOLD, then sig
is removed from the
process's signal mask.
The dispositions for SIGKILL and SIGSTOP cannot be changed.
The sighold() function adds sig
to the
calling process's signal mask.
The sigrelse() function removes sig
from
the calling process's signal mask.
The sigignore() function sets the disposition of
sig
to SIG_IGN.
On success, sigset() returns
SIG_HOLD if sig
was blocked before the call,
or the signal's previous disposition if it was not blocked before the
call. On error, sigset() returns -1, with
errno
set to indicate the error. (But see BUGS below.)
The sighold(), sigrelse(), and
sigignore() functions return 0 on success; on error,
these functions return -1 and set errno
to indicate the
error.