1.\" $OpenBSD: perror.3,v 1.8 2007/05/31 19:19:31 jmc Exp $ 2.\" 3.\" Copyright (c) 1980, 1991 Regents of the University of California. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the American National Standards Committee X3, on Information 8.\" Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.Dd $Mdocdate: May 31 2007 $ 35.Dt PERROR 3 36.Os 37.Sh NAME 38.Nm perror 39.Nd write error messages to standard error 40.Sh SYNOPSIS 41.Fd #include <stdio.h> 42.Ft void 43.Fn perror "const char *string" 44.Sh DESCRIPTION 45The 46.Fn perror 47function looks up the language-dependent error message string affiliated 48with an error number and writes it, followed by a new-line, to the 49standard error stream. 50.Pp 51If the argument 52.Fa string 53is not the 54.Dv NULL 55pointer and is not zero length, it is prepended to the message string and 56separated from it by a colon and a space 57.Pq Ql \&:\ \& . 58Otherwise, only the error message string is printed. 59.Pp 60The contents of the error message string are the same as those returned by 61.Fn strerror 62with argument 63.Fa errno . 64.Sh SEE ALSO 65.Xr intro 2 , 66.Xr psignal 3 , 67.Xr setlocale 3 , 68.Xr strerror 3 69.Sh STANDARDS 70The 71.Fn perror 72function conforms to 73.St -ansiC . 74