NetBSD/lib/libc/stdio/strerror.3

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.\" Copyright (c) 1980, 1991 Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the American National Standards Committee X3, on Information
.\" Processing Systems.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
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.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
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.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" from: @(#)strerror.3 6.9 (Berkeley) 6/29/91
.\" $Id: strerror.3,v 1.2 1993/08/01 07:44:49 mycroft Exp $
.\"
.Dd June 29, 1991
.Dt STRERROR 3
.Os BSD 4
.Sh NAME
.Nm perror ,
.Nm strerror ,
.Nm sys_errlist ,
.Nm sys_nerr
.Nd system error messages
.Sh SYNOPSIS
.Vt extern int errno;
.Vt extern char *sys_errlist[];
.Fd #include <stdio.h>
.Ft void
.Fn perror "const char *string"
.Ft char *
.Fn strerror "int errnum"
.Sh DESCRIPTION
The
.Fn strerror
and
.Fn perror
functions lookup the error message string affiliated with an
error number.
.Pp
The
.Fn sterror
function accepts an error number argument
.Fa errnum
and
returns a pointer to the corresponding
message string.
.Pp
The
.Fn perror
function finds the error message corresponding to the current
value of the global variable
.Va errno
and writes it, followed by a new-line, to the
.Em stderr .
If the argument
.Fa string
is
.Pf non- Dv NULL
it is pre-appended to the message
string and separated from it by
a colon and space
.Pq Ql \&:\ \& .
If
.Fa string
is
.Dv NULL
only the error message string is printed.
.Pp
The message strings can be accessed directly using the external
character array
.Fa sys_errlist .
The external value
.Fa sys_nerr
contains a count of the messages in
.Fa sys_errlist .
The use of these variables is deprecated;
.Fn strerror
should be used instead.
.Sh SEE ALSO
.Xr intro 2 ,
.Xr psignal 3
.Sh HISTORY
The
.Fn strerror
and
.Fn perror
functions are
.Ud .