1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd Apr 16, 2025 29.Dt PSIGNAL 3 30.Os 31.Sh NAME 32.Nm psignal , 33.Nm psiginfo , 34.Nm strsignal , 35.Nm sys_siglist , 36.Nm sys_signame 37.Nd system signal messages 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In signal.h 42.Ft void 43.Fn psignal "int sig" "const char *s" 44.Ft void 45.Fn psiginfo "const siginfo_t *si" "const char *s" 46.Vt extern const char * const sys_siglist[] ; 47.Vt extern const char * const sys_signame[] ; 48.In string.h 49.Ft "char *" 50.Fn strsignal "int sig" 51.Sh DESCRIPTION 52The 53.Fn psignal 54and 55.Fn strsignal 56functions locate the descriptive message 57string for a signal number. 58.Pp 59The 60.Fn strsignal 61function accepts a signal number argument 62.Fa sig 63and returns a pointer to the corresponding message string. 64.Pp 65The 66.Fn psignal 67function accepts a signal number argument 68.Fa sig 69and writes it to the standard error. 70If the argument 71.Fa s 72is 73.Pf non- Dv NULL 74and does not point to the null character, 75.Fa s 76is written to the standard error file descriptor 77prior to the message string, 78immediately followed by a colon and a space. 79If the signal number is not recognized 80.Pq Xr sigaction 2 , 81the string 82.Dq "Unknown signal" 83is produced. 84.Pp 85The 86.Fn psiginfo 87function is similar to 88.Fn psignal , 89except that the signal number information is taken from the 90.Fa si 91argument which is a 92.Vt siginfo_t 93structure. 94.Pp 95The message strings can be accessed directly 96through the external array 97.Va sys_siglist , 98indexed by recognized signal numbers. 99The external array 100.Va sys_signame 101is used similarly and 102contains short, upper-case abbreviations for signals 103which are useful for recognizing signal names 104in user input. 105The defined variable 106.Dv NSIG 107contains a count of the strings in 108.Va sys_siglist 109and 110.Va sys_signame . 111.Sh SEE ALSO 112.Xr sigaction 2 , 113.Xr perror 3 , 114.Xr strerror 3 115.Sh HISTORY 116The 117.Fn psignal 118function appeared in 119.Bx 4.2 . 120The 121.Fn psiginfo 122function appeared in 123.Fx 15.0 , 124.Nx 6.0 , 125and 126.Dx 4.1 . 127