#include <signal.h>
The <signal.h> header shall define the following macros, which shall expand to constant expressions with distinct values that have a type compatible with the second argument to, and the return value of, the signal() function, and whose values shall compare unequal to the address of any declarable function.
The <signal.h> header shall define the pthread_t, size_t, and uid_t types as described in <sys/types.h>.
The <signal.h> header shall define the timespec structure as described in <time.h>.
The <signal.h> header shall define the following data types:
The <signal.h> header shall define the pthread_attr_t type as described in <sys/types.h>.
The <signal.h> header shall define the sigevent structure, which shall include at least the following members:
int sigev_notify Notification type.
int sigev_signo Signal number.
union sigval sigev_value Signal value.
void (*sigev_notify_function)(union sigval)
Notification function.
pthread_attr_t *sigev_notify_attributes Notification attributes.
The <signal.h> header shall define the following symbolic constants for the values of sigev_notify:
The sigval union shall be defined as:
int sival_int Integer signal value. void *sival_ptr Pointer signal value.
The <signal.h> header shall declare the SIGRTMIN and SIGRTMAX macros, which shall expand to positive integer expressions with type int, but which need not be constant expressions. These macros specify a range of signal numbers that are reserved for application use and for which the realtime signal behavior specified in this volume of POSIX.1-2008 is supported. The signal numbers in this range do not overlap any of the signals specified in the following table.
The range SIGRTMIN through SIGRTMAX inclusive shall include at least {RTSIG_MAX} signal numbers.
It is implementation-defined whether realtime signal behavior is supported for other signals.
The <signal.h> header shall define the following macros that are used to refer to the signals that occur in the system. Signals defined here begin with the letters SIG followed by an uppercase letter. The macros shall expand to positive integer constant expressions with type int and distinct values. The value 0 is reserved for use as the null signal (see kill()). Additional implementation-defined signals may occur in the system.
The ISO C standard only requires the signal names SIGABRT, SIGFPE, SIGILL, SIGINT, SIGSEGV, and SIGTERM to be defined.
The following signals shall be supported on all implementations (default actions are explained below the table):
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The default actions are as follows:
The effects on the process in each case are described in the System Interfaces volume of POSIX.1-2008, Section 2.4.3, Signal Actions.
The <signal.h> header shall declare the sigaction structure, which shall include at least the following members:
void (*sa_handler)(int) Pointer to a signal-catching function
or one of the SIG_IGN or SIG_DFL.
sigset_t sa_mask Set of signals to be blocked during execution
of the signal handling function.
int sa_flags Special flags.
void (*sa_sigaction)(int, siginfo_t *, void *)
Pointer to a signal-catching function.
The storage occupied by sa_handler and sa_sigaction may overlap, and a conforming application shall not use both simultaneously.
The <signal.h> header shall define the following macros which shall expand to integer constant expressions that need not be usable in #if preprocessing directives:
The <signal.h> header shall also define the following symbolic constants:
The <signal.h> header shall define the mcontext_t type through typedef.
The <signal.h> header shall define the ucontext_t type as a structure that shall include at least the following members:
ucontext_t *uc_link Pointer to the context that is resumed
when this context returns.
sigset_t uc_sigmask The set of signals that are blocked when this
context is active.
stack_t uc_stack The stack used by this context.
mcontext_t uc_mcontext A machine-specific representation of the saved
context.
The <signal.h> header shall define the stack_t type as a structure, which shall include at least the following members:
void *ss_sp Stack base or pointer. size_t ss_size Stack size. int ss_flags Flags.
The <signal.h> header shall define the siginfo_t type as a structure, which shall include at least the following members:
int si_signo Signal number.
int si_code Signal code.
int si_errno If non-zero, an errno value associated with
this signal, as described in <errno.h>.
pid_t si_pid Sending process ID.
uid_t si_uid Real user ID of sending process.
void *si_addr Address of faulting instruction.
int si_status Exit value or signal.
long si_band Band event for SIGPOLL.
union sigval si_value Signal value.
The <signal.h> header shall define the symbolic constants in the Code column of the following table for use as values of si_code that are signal-specific or non-signal-specific reasons why the signal was generated.
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Implementations may support additional
si_code
values not included in this list, may generate values included in this
list under circumstances other than those described in this list, and
may contain extensions or limitations that prevent some values from
being generated. Implementations do not generate a different value from
the ones described in this list for circumstances described in this
list.
In addition, the following signal-specific information shall be available:
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For some implementations, the value of si_addr may be inaccurate.
The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.
int kill(pid_t, int);
int killpg(pid_t, int);
void psiginfo(const siginfo_t *, const char *);
void psignal(int, const char *);
int pthread_kill(pthread_t, int);
int pthread_sigmask(int, const sigset_t *restrict,
sigset_t *restrict);
int raise(int);
int sigaction(int, const struct sigaction *restrict,
struct sigaction *restrict);
int sigaddset(sigset_t *, int);
int sigaltstack(const stack_t *restrict, stack_t *restrict);
int sigdelset(sigset_t *, int);
int sigemptyset(sigset_t *);
int sigfillset(sigset_t *);
int sighold(int);
int sigignore(int);
int siginterrupt(int, int);
int sigismember(const sigset_t *, int);
void (*signal(int, void (*)(int)))(int);
int sigpause(int);
int sigpending(sigset_t *);
int sigprocmask(int, const sigset_t *restrict, sigset_t *restrict);
int sigqueue(pid_t, int, const union sigval);
int sigrelse(int);
void (*sigset(int, void (*)(int)))(int);
int sigsuspend(const sigset_t *);
int sigtimedwait(const sigset_t *restrict, siginfo_t *restrict,
const struct timespec *restrict);
int sigwait(const sigset_t *restrict, int *restrict);
int sigwaitinfo(const sigset_t *restrict, siginfo_t *restrict);
Inclusion of the <signal.h> header may make visible all symbols from the <time.h> header.
The following sections are informative.
The System Interfaces volume of POSIX.1-2008, Section 2.2, The Compilation Environment, alarm(), ioctl(), kill(), killpg(), psiginfo(), pthread_kill(), pthread_sigmask(), raise(), sigaction(), sigaddset(), sigaltstack(), sigdelset(), sigemptyset(), sigfillset(), sighold(), siginterrupt(), sigismember(), signal(), sigpending(), sigqueue(), sigsuspend(), sigtimedwait(), sigwait(), timer_create(), wait(), waitid()
Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .