1SIGACTION(2) Linux Programmer's Manual SIGACTION(2)
2
6 sigaction, rt_sigaction - examine and change a signal action
7
9 #include <signal.h>
10 int sigaction(int signum, const struct sigaction *restrict act,
12 struct sigaction *restrict oldact);
13 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
15 sigaction():
17 _POSIX_C_SOURCE
18 siginfo_t:
20 _POSIX_C_SOURCE >= 199309L
21
23 The sigaction() system call is used to change the action taken by a
24 process on receipt of a specific signal. (See signal(7) for an over‐
25 view of signals.)
26 signum specifies the signal and can be any valid signal except SIGKILL
28 and SIGSTOP.
29 If act is non-NULL, the new action for signal signum is installed from
31 act. If oldact is non-NULL, the previous action is saved in oldact.
32 The sigaction structure is defined as something like:
34 struct sigaction {
36 void (*sa_handler)(int);
37 void (*sa_sigaction)(int, siginfo_t *, void *);
38 sigset_t sa_mask;
39 int sa_flags;
40 void (*sa_restorer)(void);
41 };
42 On some architectures a union is involved: do not assign to both
44 sa_handler and sa_sigaction.
45 The sa_restorer field is not intended for application use. (POSIX does
47 not specify a sa_restorer field.) Some further details of the purpose
48 of this field can be found in sigreturn(2).
49 sa_handler specifies the action to be associated with signum and is be
51 one of the following:
52 * SIG_DFL for the default action.
54 * SIG_IGN to ignore this signal.
56 * A pointer to a signal handling function. This function receives the
58 signal number as its only argument.
59 If SA_SIGINFO is specified in sa_flags, then sa_sigaction (instead of
61 sa_handler) specifies the signal-handling function for signum. This
62 function receives three arguments, as described below.
63 sa_mask specifies a mask of signals which should be blocked (i.e.,
65 added to the signal mask of the thread in which the signal handler is
66 invoked) during execution of the signal handler. In addition, the sig‐
67 nal which triggered the handler will be blocked, unless the SA_NODEFER
68 flag is used.
69 sa_flags specifies a set of flags which modify the behavior of the sig‐
71 nal. It is formed by the bitwise OR of zero or more of the following:
72 SA_NOCLDSTOP
74 If signum is SIGCHLD, do not receive notification when child
75 processes stop (i.e., when they receive one of SIGSTOP, SIGTSTP,
76 SIGTTIN, or SIGTTOU) or resume (i.e., they receive SIGCONT) (see
77 wait(2)). This flag is meaningful only when establishing a han‐
78 dler for SIGCHLD.
79 SA_NOCLDWAIT (since Linux 2.6)
81 If signum is SIGCHLD, do not transform children into zombies
82 when they terminate. See also waitpid(2). This flag is mean‐
83 ingful only when establishing a handler for SIGCHLD, or when
84 setting that signal's disposition to SIG_DFL.
85 If the SA_NOCLDWAIT flag is set when establishing a handler for
87 SIGCHLD, POSIX.1 leaves it unspecified whether a SIGCHLD signal
88 is generated when a child process terminates. On Linux, a
89 SIGCHLD signal is generated in this case; on some other imple‐
90 mentations, it is not.
91 SA_NODEFER
93 Do not add the signal to the thread's signal mask while the han‐
94 dler is executing, unless the signal is specified in
95 act.sa_mask. Consequently, a further instance of the signal may
96 be delivered to the thread while it is executing the handler.
97 This flag is meaningful only when establishing a signal handler.
98 SA_NOMASK is an obsolete, nonstandard synonym for this flag.
100 SA_ONSTACK
102 Call the signal handler on an alternate signal stack provided by
103 sigaltstack(2). If an alternate stack is not available, the de‐
104 fault stack will be used. This flag is meaningful only when es‐
105 tablishing a signal handler.
106 SA_RESETHAND
108 Restore the signal action to the default upon entry to the sig‐
109 nal handler. This flag is meaningful only when establishing a
110 signal handler.
111 SA_ONESHOT is an obsolete, nonstandard synonym for this flag.
113 SA_RESTART
115 Provide behavior compatible with BSD signal semantics by making
116 certain system calls restartable across signals. This flag is
117 meaningful only when establishing a signal handler. See sig‐
118 nal(7) for a discussion of system call restarting.
119 SA_RESTORER
121 Not intended for application use. This flag is used by C li‐
122 braries to indicate that the sa_restorer field contains the ad‐
123 dress of a "signal trampoline". See sigreturn(2) for more de‐
124 tails.
125 SA_SIGINFO (since Linux 2.2)
127 The signal handler takes three arguments, not one. In this
128 case, sa_sigaction should be set instead of sa_handler. This
129 flag is meaningful only when establishing a signal handler.
130 SA_UNSUPPORTED (since Linux 5.11)
132 Used to dynamically probe for flag bit support.
133 If an attempt to register a handler succeeds with this flag set
135 in act->sa_flags alongside other flags that are potentially un‐
136 supported by the kernel, and an immediately subsequent sigac‐
137 tion() call specifying the same signal number and with a non-
138 NULL oldact argument yields SA_UNSUPPORTED clear in
139 oldact->sa_flags, then oldact->sa_flags may be used as a bitmask
140 describing which of the potentially unsupported flags are, in
141 fact, supported. See the section "Dynamically probing for flag
142 bit support" below for more details.
143 SA_EXPOSE_TAGBITS (since Linux 5.11)
145 Normally, when delivering a signal, an architecture-specific set
146 of tag bits are cleared from the si_addr field of siginfo_t. If
147 this flag is set, an architecture-specific subset of the tag
148 bits will be preserved in si_addr.
149 Programs that need to be compatible with Linux versions older
151 than 5.11 must use SA_UNSUPPORTED to probe for support.
152 The siginfo_t argument to a SA_SIGINFO handler
154 When the SA_SIGINFO flag is specified in act.sa_flags, the signal han‐
155 dler address is passed via the act.sa_sigaction field. This handler
156 takes three arguments, as follows:
157 void
159 handler(int sig, siginfo_t *info, void *ucontext)
160 {
161 ...
162 }
163 These three arguments are as follows
165 sig The number of the signal that caused invocation of the handler.
167 info A pointer to a siginfo_t, which is a structure containing fur‐
169 ther information about the signal, as described below.
170 ucontext
172 This is a pointer to a ucontext_t structure, cast to void *.
173 The structure pointed to by this field contains signal context
174 information that was saved on the user-space stack by the ker‐
175 nel; for details, see sigreturn(2). Further information about
176 the ucontext_t structure can be found in getcontext(3) and sig‐
177 nal(7). Commonly, the handler function doesn't make any use of
178 the third argument.
179 The siginfo_t data type is a structure with the following fields:
181 siginfo_t {
183 int si_signo; /* Signal number */
184 int si_errno; /* An errno value */
185 int si_code; /* Signal code */
186 int si_trapno; /* Trap number that caused
187 hardware-generated signal
188 (unused on most architectures) */
189 pid_t si_pid; /* Sending process ID */
190 uid_t si_uid; /* Real user ID of sending process */
191 int si_status; /* Exit value or signal */
192 clock_t si_utime; /* User time consumed */
193 clock_t si_stime; /* System time consumed */
194 union sigval si_value; /* Signal value */
195 int si_int; /* POSIX.1b signal */
196 void *si_ptr; /* POSIX.1b signal */
197 int si_overrun; /* Timer overrun count;
198 POSIX.1b timers */
199 int si_timerid; /* Timer ID; POSIX.1b timers */
200 void *si_addr; /* Memory location which caused fault */
201 long si_band; /* Band event (was int in
202 glibc 2.3.2 and earlier) */
203 int si_fd; /* File descriptor */
204 short si_addr_lsb; /* Least significant bit of address
205 (since Linux 2.6.32) */
206 void *si_lower; /* Lower bound when address violation
207 occurred (since Linux 3.19) */
208 void *si_upper; /* Upper bound when address violation
209 occurred (since Linux 3.19) */
210 int si_pkey; /* Protection key on PTE that caused
211 fault (since Linux 4.6) */
212 void *si_call_addr; /* Address of system call instruction
213 (since Linux 3.5) */
214 int si_syscall; /* Number of attempted system call
215 (since Linux 3.5) */
216 unsigned int si_arch; /* Architecture of attempted system call
217 (since Linux 3.5) */
218 }
219 si_signo, si_errno and si_code are defined for all signals. (si_errno
221 is generally unused on Linux.) The rest of the struct may be a union,
222 so that one should read only the fields that are meaningful for the
223 given signal:
224 * Signals sent with kill(2) and sigqueue(3) fill in si_pid and si_uid.
226 In addition, signals sent with sigqueue(3) fill in si_int and si_ptr
227 with the values specified by the sender of the signal; see
228 sigqueue(3) for more details.
229 * Signals sent by POSIX.1b timers (since Linux 2.6) fill in si_overrun
231 and si_timerid. The si_timerid field is an internal ID used by the
232 kernel to identify the timer; it is not the same as the timer ID re‐
233 turned by timer_create(2). The si_overrun field is the timer overrun
234 count; this is the same information as is obtained by a call to
235 timer_getoverrun(2). These fields are nonstandard Linux extensions.
236 * Signals sent for message queue notification (see the description of
238 SIGEV_SIGNAL in mq_notify(3)) fill in si_int/si_ptr, with the
239 sigev_value supplied to mq_notify(3); si_pid, with the process ID of
240 the message sender; and si_uid, with the real user ID of the message
241 sender.
242 * SIGCHLD fills in si_pid, si_uid, si_status, si_utime, and si_stime,
244 providing information about the child. The si_pid field is the
245 process ID of the child; si_uid is the child's real user ID. The
246 si_status field contains the exit status of the child (if si_code is
247 CLD_EXITED), or the signal number that caused the process to change
248 state. The si_utime and si_stime contain the user and system CPU
249 time used by the child process; these fields do not include the times
250 used by waited-for children (unlike getrusage(2) and times(2)). In
251 kernels up to 2.6, and since 2.6.27, these fields report CPU time in
252 units of sysconf(_SC_CLK_TCK). In 2.6 kernels before 2.6.27, a bug
253 meant that these fields reported time in units of the (configurable)
254 system jiffy (see time(7)).
255 * SIGILL, SIGFPE, SIGSEGV, SIGBUS, and SIGTRAP fill in si_addr with the
257 address of the fault. On some architectures, these signals also fill
258 in the si_trapno field.
259 Some suberrors of SIGBUS, in particular BUS_MCEERR_AO and
261 BUS_MCEERR_AR, also fill in si_addr_lsb. This field indicates the
262 least significant bit of the reported address and therefore the ex‐
263 tent of the corruption. For example, if a full page was corrupted,
264 si_addr_lsb contains log2(sysconf(_SC_PAGESIZE)). When SIGTRAP is
265 delivered in response to a ptrace(2) event (PTRACE_EVENT_foo),
266 si_addr is not populated, but si_pid and si_uid are populated with
267 the respective process ID and user ID responsible for delivering the
268 trap. In the case of seccomp(2), the tracee will be shown as deliv‐
269 ering the event. BUS_MCEERR_* and si_addr_lsb are Linux-specific ex‐
270 tensions.
271 The SEGV_BNDERR suberror of SIGSEGV populates si_lower and si_upper.
273 The SEGV_PKUERR suberror of SIGSEGV populates si_pkey.
275 * SIGIO/SIGPOLL (the two names are synonyms on Linux) fills in si_band
277 and si_fd. The si_band event is a bit mask containing the same val‐
278 ues as are filled in the revents field by poll(2). The si_fd field
279 indicates the file descriptor for which the I/O event occurred; for
280 further details, see the description of F_SETSIG in fcntl(2).
281 * SIGSYS, generated (since Linux 3.5) when a seccomp filter returns
283 SECCOMP_RET_TRAP, fills in si_call_addr, si_syscall, si_arch, si_er‐
284 rno, and other fields as described in seccomp(2).
285 The si_code field
287 The si_code field inside the siginfo_t argument that is passed to a
288 SA_SIGINFO signal handler is a value (not a bit mask) indicating why
289 this signal was sent. For a ptrace(2) event, si_code will contain SIG‐
290 TRAP and have the ptrace event in the high byte:
291 (SIGTRAP | PTRACE_EVENT_foo << 8).
293 For a non-ptrace(2) event, the values that can appear in si_code are
295 described in the remainder of this section. Since glibc 2.20, the def‐
296 initions of most of these symbols are obtained from <signal.h> by
297 defining feature test macros (before including any header file) as fol‐
298 lows:
299 * _XOPEN_SOURCE with the value 500 or greater;
301 * _XOPEN_SOURCE and _XOPEN_SOURCE_EXTENDED; or
303 * _POSIX_C_SOURCE with the value 200809L or greater.
305 For the TRAP_* constants, the symbol definitions are provided only in
307 the first two cases. Before glibc 2.20, no feature test macros were
308 required to obtain these symbols.
309 For a regular signal, the following list shows the values which can be
311 placed in si_code for any signal, along with the reason that the signal
312 was generated.
313 SI_USER
315 kill(2).
316 SI_KERNEL
318 Sent by the kernel.
319 SI_QUEUE
321 sigqueue(3).
322 SI_TIMER
324 POSIX timer expired.
325 SI_MESGQ (since Linux 2.6.6)
327 POSIX message queue state changed; see mq_notify(3).
328 SI_ASYNCIO
330 AIO completed.
331 SI_SIGIO
333 Queued SIGIO (only in kernels up to Linux 2.2; from Linux
334 2.4 onward SIGIO/SIGPOLL fills in si_code as described be‐
335 low).
336 SI_TKILL (since Linux 2.4.19)
338 tkill(2) or tgkill(2).
339 The following values can be placed in si_code for a SIGILL signal:
341 ILL_ILLOPC
343 Illegal opcode.
344 ILL_ILLOPN
346 Illegal operand.
347 ILL_ILLADR
349 Illegal addressing mode.
350 ILL_ILLTRP
352 Illegal trap.
353 ILL_PRVOPC
355 Privileged opcode.
356 ILL_PRVREG
358 Privileged register.
359 ILL_COPROC
361 Coprocessor error.
362 ILL_BADSTK
364 Internal stack error.
365 The following values can be placed in si_code for a SIGFPE signal:
367 FPE_INTDIV
369 Integer divide by zero.
370 FPE_INTOVF
372 Integer overflow.
373 FPE_FLTDIV
375 Floating-point divide by zero.
376 FPE_FLTOVF
378 Floating-point overflow.
379 FPE_FLTUND
381 Floating-point underflow.
382 FPE_FLTRES
384 Floating-point inexact result.
385 FPE_FLTINV
387 Floating-point invalid operation.
388 FPE_FLTSUB
390 Subscript out of range.
391 The following values can be placed in si_code for a SIGSEGV signal:
393 SEGV_MAPERR
395 Address not mapped to object.
396 SEGV_ACCERR
398 Invalid permissions for mapped object.
399 SEGV_BNDERR (since Linux 3.19)
401 Failed address bound checks.
402 SEGV_PKUERR (since Linux 4.6)
404 Access was denied by memory protection keys. See pkeys(7).
405 The protection key which applied to this access is available
406 via si_pkey.
407 The following values can be placed in si_code for a SIGBUS signal:
409 BUS_ADRALN
411 Invalid address alignment.
412 BUS_ADRERR
414 Nonexistent physical address.
415 BUS_OBJERR
417 Object-specific hardware error.
418 BUS_MCEERR_AR (since Linux 2.6.32)
420 Hardware memory error consumed on a machine check; action
421 required.
422 BUS_MCEERR_AO (since Linux 2.6.32)
424 Hardware memory error detected in process but not consumed;
425 action optional.
426 The following values can be placed in si_code for a SIGTRAP signal:
428 TRAP_BRKPT
430 Process breakpoint.
431 TRAP_TRACE
433 Process trace trap.
434 TRAP_BRANCH (since Linux 2.4, IA64 only)
436 Process taken branch trap.
437 TRAP_HWBKPT (since Linux 2.4, IA64 only)
439 Hardware breakpoint/watchpoint.
440 The following values can be placed in si_code for a SIGCHLD signal:
442 CLD_EXITED
444 Child has exited.
445 CLD_KILLED
447 Child was killed.
448 CLD_DUMPED
450 Child terminated abnormally.
451 CLD_TRAPPED
453 Traced child has trapped.
454 CLD_STOPPED
456 Child has stopped.
457 CLD_CONTINUED (since Linux 2.6.9)
459 Stopped child has continued.
460 The following values can be placed in si_code for a SIGIO/SIGPOLL sig‐
462 nal:
463 POLL_IN
465 Data input available.
466 POLL_OUT
468 Output buffers available.
469 POLL_MSG
471 Input message available.
472 POLL_ERR
474 I/O error.
475 POLL_PRI
477 High priority input available.
478 POLL_HUP
480 Device disconnected.
481 The following value can be placed in si_code for a SIGSYS signal:
483 SYS_SECCOMP (since Linux 3.5)
485 Triggered by a seccomp(2) filter rule.
486 Dynamically probing for flag bit support
488 The sigaction() call on Linux accepts unknown bits set in act->sa_flags
489 without error. The behavior of the kernel starting with Linux 5.11 is
490 that a second sigaction() will clear unknown bits from
491 oldact->sa_flags. However, historically, a second sigaction() call
492 would typically leave those bits set in oldact->sa_flags.
493 This means that support for new flags cannot be detected simply by
495 testing for a flag in sa_flags, and a program must test that SA_UNSUP‐
496 PORTED has been cleared before relying on the contents of sa_flags.
497 Since the behavior of the signal handler cannot be guaranteed unless
499 the check passes, it is wise to either block the affected signal while
500 registering the handler and performing the check in this case, or where
501 this is not possible, for example if the signal is synchronous, to is‐
502 sue the second sigaction() in the signal handler itself.
503 In kernels that do not support a specific flag, the kernel's behavior
505 is as if the flag was not set, even if the flag was set in
506 act->sa_flags.
507 The flags SA_NOCLDSTOP, SA_NOCLDWAIT, SA_SIGINFO, SA_ONSTACK,
509 SA_RESTART, SA_NODEFER, SA_RESETHAND, and, if defined by the architec‐
510 ture, SA_RESTORER may not be reliably probed for using this mechanism,
511 because they were introduced before Linux 5.11. However, in general,
512 programs may assume that these flags are supported, since they have all
513 been supported since Linux 2.6, which was released in the year 2003.
514 See EXAMPLES below for a demonstration of the use of SA_UNSUPPORTED.
516
518 sigaction() returns 0 on success; on error, -1 is returned, and errno
519 is set to indicate the error.
520
522 EFAULT act or oldact points to memory which is not a valid part of the
523 process address space.
524 EINVAL An invalid signal was specified. This will also be generated if
526 an attempt is made to change the action for SIGKILL or SIGSTOP,
527 which cannot be caught or ignored.
528
530 POSIX.1-2001, POSIX.1-2008, SVr4.
531
533 A child created via fork(2) inherits a copy of its parent's signal dis‐
534 positions. During an execve(2), the dispositions of handled signals
535 are reset to the default; the dispositions of ignored signals are left
536 unchanged.
537 According to POSIX, the behavior of a process is undefined after it ig‐
539 nores a SIGFPE, SIGILL, or SIGSEGV signal that was not generated by
540 kill(2) or raise(3). Integer division by zero has undefined result.
541 On some architectures it will generate a SIGFPE signal. (Also dividing
542 the most negative integer by -1 may generate SIGFPE.) Ignoring this
543 signal might lead to an endless loop.
544 POSIX.1-1990 disallowed setting the action for SIGCHLD to SIG_IGN.
546 POSIX.1-2001 and later allow this possibility, so that ignoring SIGCHLD
547 can be used to prevent the creation of zombies (see wait(2)). Never‐
548 theless, the historical BSD and System V behaviors for ignoring SIGCHLD
549 differ, so that the only completely portable method of ensuring that
550 terminated children do not become zombies is to catch the SIGCHLD sig‐
551 nal and perform a wait(2) or similar.
552 POSIX.1-1990 specified only SA_NOCLDSTOP. POSIX.1-2001 added SA_NOCLD‐
554 STOP, SA_NOCLDWAIT, SA_NODEFER, SA_ONSTACK, SA_RESETHAND, SA_RESTART,
555 and SA_SIGINFO. Use of these latter values in sa_flags may be less
556 portable in applications intended for older UNIX implementations.
557 The SA_RESETHAND flag is compatible with the SVr4 flag of the same
559 name.
560 The SA_NODEFER flag is compatible with the SVr4 flag of the same name
562 under kernels 1.3.9 and later. On older kernels the Linux implementa‐
563 tion allowed the receipt of any signal, not just the one we are in‐
564 stalling (effectively overriding any sa_mask settings).
565 sigaction() can be called with a NULL second argument to query the cur‐
567 rent signal handler. It can also be used to check whether a given sig‐
568 nal is valid for the current machine by calling it with NULL second and
569 third arguments.
570 It is not possible to block SIGKILL or SIGSTOP (by specifying them in
572 sa_mask). Attempts to do so are silently ignored.
573 See sigsetops(3) for details on manipulating signal sets.
575 See signal-safety(7) for a list of the async-signal-safe functions that
577 can be safely called inside from inside a signal handler.
578 C library/kernel differences
580 The glibc wrapper function for sigaction() gives an error (EINVAL) on
581 attempts to change the disposition of the two real-time signals used
582 internally by the NPTL threading implementation. See nptl(7) for de‐
583 tails.
584 On architectures where the signal trampoline resides in the C library,
586 the glibc wrapper function for sigaction() places the address of the
587 trampoline code in the act.sa_restorer field and sets the SA_RESTORER
588 flag in the act.sa_flags field. See sigreturn(2).
589 The original Linux system call was named sigaction(). However, with
591 the addition of real-time signals in Linux 2.2, the fixed-size, 32-bit
592 sigset_t type supported by that system call was no longer fit for pur‐
593 pose. Consequently, a new system call, rt_sigaction(), was added to
594 support an enlarged sigset_t type. The new system call takes a fourth
595 argument, size_t sigsetsize, which specifies the size in bytes of the
596 signal sets in act.sa_mask and oldact.sa_mask. This argument is cur‐
597 rently required to have the value sizeof(sigset_t) (or the error EINVAL
598 results). The glibc sigaction() wrapper function hides these details
599 from us, transparently calling rt_sigaction() when the kernel provides
600 it.
601 Undocumented
603 Before the introduction of SA_SIGINFO, it was also possible to get some
604 additional information about the signal. This was done by providing an
605 sa_handler signal handler with a second argument of type struct sigcon‐
606 text, which is the same structure as the one that is passed in the
607 uc_mcontext field of the ucontext structure that is passed (via a
608 pointer) in the third argument of the sa_sigaction handler. See the
609 relevant Linux kernel sources for details. This use is obsolete now.
610
612 When delivering a signal with a SA_SIGINFO handler, the kernel does not
613 always provide meaningful values for all of the fields of the siginfo_t
614 that are relevant for that signal.
615 In kernels up to and including 2.6.13, specifying SA_NODEFER in
617 sa_flags prevents not only the delivered signal from being masked dur‐
618 ing execution of the handler, but also the signals specified in
619 sa_mask. This bug was fixed in kernel 2.6.14.
620
622 See mprotect(2).
623 Probing for flag support
625 The following example program exits with status EXIT_SUCCESS if SA_EX‐
626 POSE_TAGBITS is determined to be supported, and EXIT_FAILURE otherwise.
627 #include <signal.h>
629 #include <stdlib.h>
630 #include <stdio.h>
631 #include <unistd.h>
632 void
634 handler(int signo, siginfo_t *info, void *context)
635 {
636 struct sigaction oldact;
637 if (sigaction(SIGSEGV, NULL, &oldact) == -1 ||
639 (oldact.sa_flags & SA_UNSUPPORTED) ||
640 !(oldact.sa_flags & SA_EXPOSE_TAGBITS)) {
641 _exit(EXIT_FAILURE);
642 }
643 _exit(EXIT_SUCCESS);
644 }
645 int
647 main(void)
648 {
649 struct sigaction act = { 0 };
650 act.sa_flags = SA_SIGINFO | SA_UNSUPPORTED | SA_EXPOSE_TAGBITS;
652 act.sa_sigaction = &handler;
653 if (sigaction(SIGSEGV, &act, NULL) == -1) {
654 perror("sigaction");
655 exit(EXIT_FAILURE);
656 }
657 raise(SIGSEGV);
659 }
660
662 kill(1), kill(2), pause(2), pidfd_send_signal(2), restart_syscall(2),
663 seccomp(2), sigaltstack(2), signal(2), signalfd(2), sigpending(2), sig‐
664 procmask(2), sigreturn(2), sigsuspend(2), wait(2), killpg(3), raise(3),
665 siginterrupt(3), sigqueue(3), sigsetops(3), sigvec(3), core(5), sig‐
666 nal(7)
667
669 This page is part of release 5.13 of the Linux man-pages project. A
670 description of the project, information about reporting bugs, and the
671 latest version of this page, can be found at
672 https://www.kernel.org/doc/man-pages/.
673Linux 2021-08-27 SIGACTION(2)