1.\" $OpenBSD: perror.3,v 1.2 1996/08/19 08:32:56 tholo 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. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.Dd June 29, 1991 39.Dt PERROR 3 40.Os BSD 4 41.Sh NAME 42.Nm perror 43.Nd write error messages to standard error 44.Sh SYNOPSIS 45.Fd #include <stdio.h> 46.Ft void 47.Fn perror "const char *string" 48.Sh DESCRIPTION 49The 50.Fn perror 51function looks up the language-dependent error message string affiliated 52with an error number and writes it, followed by a new-line, to the 53standard error stream. 54.Pp 55If the argument 56.Fa string 57is 58.Pf non- Dv NULL 59it is prepended to the message string and separated from it by 60a colon and a space 61.Pq Ql \&:\ \& . 62If 63.Fa string 64is 65.Dv NULL 66only the error message string is printed. 67.Pp 68The contents of the error message string is the same as those returned by 69.Fn strerror 70with argument 71.Fa errno . 72.Sh SEE ALSO 73.Xr intro 2 , 74.Xr psignal 3 , 75.Xr setlocale 3 , 76.Xr strerror 3 77.Sh STANDARDS 78The 79.Fn perror 80function conforms to 81.St -ansiC . 82