sigemptyset(3)

1SIGSETOPS(3)               Library Functions Manual               SIGSETOPS(3)
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NAME

6       sigemptyset, sigfillset, sigaddset, sigdelset, sigismember - POSIX sig‐
7       nal set operations
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LIBRARY

10       Standard C library (libc, -lc)
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SYNOPSIS

13       #include <signal.h>
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15       int sigemptyset(sigset_t *set);
16       int sigfillset(sigset_t *set);
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18       int sigaddset(sigset_t *set, int signum);
19       int sigdelset(sigset_t *set, int signum);
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21       int sigismember(const sigset_t *set, int signum);
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23   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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25       sigemptyset(), sigfillset(), sigaddset(), sigdelset(), sigismember():
26           _POSIX_C_SOURCE
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DESCRIPTION

29       These functions allow the manipulation of POSIX signal sets.
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31       sigemptyset() initializes the signal set given by set  to  empty,  with
32       all signals excluded from the set.
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34       sigfillset() initializes set to full, including all signals.
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36       sigaddset()  and  sigdelset() add and delete respectively signal signum
37       from set.
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39       sigismember() tests whether signum is a member of set.
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41       Objects of type sigset_t must  be  initialized  by  a  call  to  either
42       sigemptyset()  or  sigfillset()  before  being  passed to the functions
43       sigaddset(), sigdelset(), and sigismember()  or  the  additional  glibc
44       functions  described  below  (sigisemptyset(),  sigandset(),  and  sig‐
45       orset()).  The results are undefined if this is not done.
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RETURN VALUE

48       sigemptyset(), sigfillset(), sigaddset(), and sigdelset() return  0  on
49       success and -1 on error.
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51       sigismember()  returns  1  if signum is a member of set, 0 if signum is
52       not a member, and -1 on error.
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54       On error, these functions set errno to indicate the error.
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ERRORS

57       EINVAL signum is not a valid signal.
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ATTRIBUTES

60       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
61       tributes(7).
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63       ┌────────────────────────────────────────────┬───────────────┬─────────┐
64       │Interface                                   │ Attribute     │ Value   │
65       ├────────────────────────────────────────────┼───────────────┼─────────┤
66       │sigemptyset(), sigfillset(), sigaddset(),   │ Thread safety │ MT-Safe │
67       │sigdelset(), sigismember(),                 │               │         │
68       │sigisemptyset(), sigorset(), sigandset()    │               │         │
69       └────────────────────────────────────────────┴───────────────┴─────────┘
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VERSIONS

72   GNU
73       If  the  _GNU_SOURCE feature test macro is defined, then <signal.h> ex‐
74       poses three other functions for manipulating signal sets:
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76       int sigisemptyset(const sigset_t *set);
77       int sigorset(sigset_t *dest, const sigset_t *left,
78                     const sigset_t *right);
79       int sigandset(sigset_t *dest, const sigset_t *left,
80                     const sigset_t *right);
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82       sigisemptyset() returns 1 if set contains no signals, and 0 otherwise.
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84       sigorset() places the union  of  the  sets  left  and  right  in  dest.
85       sigandset() places the intersection of the sets left and right in dest.
86       Both functions return 0 on success, and -1 on failure.
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88       These functions are nonstandard (a few other  systems  provide  similar
89       functions) and their use should be avoided in portable applications.
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STANDARDS

92       POSIX.1-2008.
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HISTORY

95       POSIX.1-2001.
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NOTES

98       When creating a filled signal set, the glibc sigfillset() function does
99       not include the two real-time  signals  used  internally  by  the  NPTL
100       threading implementation.  See nptl(7) for details.
101