man3/strsignal.3

.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\" and Copyright (C) 2020 Michael Kerrisk <mtk.manpages@gmail.com>
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.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sat Jul 24 17:59:03 1993 by Rik Faith (faith@cs.unc.edu)
.TH STRSIGNAL 3  2021-03-22 "GNU" "Linux Programmer's Manual"
.SH NAME
strsignal, sigdescr_np, sigdescr_np, sys_siglist \- return string describing signal
.SH SYNOPSIS
.nf
.B #include <string.h>
.PP
.BI "char *strsignal(int " sig );
.BI "char *sigdescr_np(int " sig );
.BI "char *sigabbrev_np(int " sig );
.PP
.BI "extern const char * const " sys_siglist [];
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR sigabbrev_np (),
.BR sigdescr_np ():
.nf
    _GNU_SOURCE
.fi
.PP
.BR strsignal ():
.nf
    From glibc 2.10 to 2.31:
        _POSIX_C_SOURCE >= 200809L
    Before glibc 2.10:
        _GNU_SOURCE
.fi
.PP
.IR sys_siglist :
.nf
    Since glibc 2.19:
        _DEFAULT_SOURCE
    Glibc 2.19 and earlier:
        _BSD_SOURCE
.fi
.SH DESCRIPTION
The
.BR strsignal ()
function returns a string describing the signal
number passed in the argument
.IR sig .
The string can be used only until the next call to
.BR strsignal ().
The string returned by
.BR strsignal ()
is localized according to the
.B LC_MESSAGES
category in the current locale.
.PP
The
.BR sigdescr_np ()
function returns a string describing the signal
number passed in the argument
.IR sig .
Unlike
.BR strsignal ()
this string is not influenced by the current locale.
.PP
The
.BR sigabbrev_np ()
function returns the abbreviated name of the signal,
.IR sig .
For example, given the value
.BR SIGINT ,
it returns the string "INT".
.PP
The (deprecated) array
.I sys_siglist
holds the signal description strings
indexed by signal number.
The
.BR strsignal ()
or the
.BR sigdescr_np ()
function should be used instead of this array; see also VERSIONS.
.SH RETURN VALUE
The
.BR strsignal ()
function returns the appropriate description
string, or an unknown signal message if the signal number is invalid.
On some systems (but not on Linux), NULL may instead be
returned for an invalid signal number.
.PP
The
.BR sigdescr_np ()
and
.BR sigdabbrev_np ()
functions return the appropriate description string.
The returned string is statically allocated and valid for
the lifetime of the program.
These functions return NULL for an invalid signal number.
.SH VERSIONS
.BR sigdescr_np ()
and
.BR sigdabbrev_np ()
first appeared in glibc 2.32.
.PP
Starting with version 2.32,
.\" glibc commit b1ccfc061feee9ce616444ded8e1cd5acf9fa97f
the
.I sys_siglist
symbol is no longer exported by glibc.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lb lb lbx
l l l.
Interface	Attribute	Value
T{
.BR strsignal ()
T}	Thread safety	T{
MT-Unsafe race:strsignal locale
T}
T{
.BR sigdescr_np (),
.BR sigabbrev_np ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH CONFORMING TO
.BR strsignal ():
POSIX.1-2008.
Present on Solaris and the BSDs.
.PP
.BR sigdescr_np ()
and
.BR sigdabbrev_np ()
are GNU extensions.
.PP
.I sys_siglist
is nonstandard, but present on many other systems.
.SH NOTES
.BR sigdescr_np ()
and
.BR sigdabbrev_np ()
are thread-safe and async-signal-safe.
.SH SEE ALSO
.BR psignal (3),
.BR strerror (3)