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.\" Copyright (c) 1993
.\" The Regents of the University of California. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" 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
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" From: @(#)err.3 8.1 (Berkeley) 6/9/93
.\" $FreeBSD: src/lib/libc/gen/err.3,v 1.11.2.5 2001/08/17 15:42:32 ru Exp $
.\"
.\" 2007-12-08, mtk, Converted from mdoc to man macros
.\"
.TH ERR 3 2007-12-08 "Linux" "Linux Programmer's Manual"
.SH NAME
err, verr, errx, verrx, warn, vwarn, warnx, vwarnx \- formatted error messages
.SH SYNOPSIS
.nf
.B #include <err.h>
.sp
.BI "void err(int " eval ", const char *" fmt ", ...);"
.sp
.BI "void errx(int " eval ", const char *" fmt ", ...);"
.sp
.BI "void warn(const char *" fmt ", ...);"
.sp
.BI "void warnx(const char *" fmt ", ...);"
.sp
.B #include <stdarg.h>
.sp
.BI "void verr(int " eval ", const char *" fmt ", va_list " args );
.sp
.BI "void verrx(int " eval ", const char *" fmt ", va_list " args );
.sp
.BI "void vwarn(const char *" fmt ", va_list " args );
.sp
.BI "void vwarnx(const char *" fmt ", va_list " args );
.fi
.SH DESCRIPTION
The
.BR err ()
and
.BR warn ()
family of functions display a formatted error message on the standard
error output.
In all cases, the last component of the program name, a colon character,
and a space are output.
If the
.I fmt
argument is not NULL, the
.BR printf (3)-like
formatted error message is output.
The output is terminated by a newline character.
.sp
The
.BR err (),
.BR verr (),
.BR warn (),
and
.BR vwarn ()
functions append an error message obtained from
.BR strerror (3)
based on a code or the global variable
.IR errno ,
preceded by another colon and space unless the
.I fmt
argument is
NULL.
.sp
The
.BR err (),
.BR verr (),
.BR warn (),
and
.BR vwarn ()
functions use the global variable
.I errno
to look up the error message.
.sp
The
.BR errx ()
and
.BR warnx ()
functions do not append an error message.
.sp
The
.BR err (),
.BR verr (),
.BR errx (),
and
.BR verrx ()
functions do not return, but exit with the value of the argument
.IR eval .
.SH EXAMPLES
Display the current errno information string and exit:
.in +0.5i
.nf
if ((p = malloc(size)) == NULL)
err(1, NULL);
if ((fd = open(file_name, O_RDONLY, 0)) == \-1)
err(1, "%s", file_name);
.fi
.in
.sp
Display an error message and exit:
.in +0.5i
.nf
if (tm.tm_hour < START_TIME)
errx(1, "too early, wait until %s", start_time_string);
.fi
.in
.sp
Warn of an error:
.in +0.5i
.nf
if ((fd = open(raw_device, O_RDONLY, 0)) == \-1)
warnx("%s: %s: trying the block device",
raw_device, strerror(errno));
if ((fd = open(block_device, O_RDONLY, 0)) == \-1)
err(1, "%s", block_device);
.fi
.in
.SH "CONFORMING TO"
These functions are non-standard BSD extensions.
.\" .SH HISTORY
.\" The
.\" .BR err ()
.\" and
.\" .BR warn ()
.\" functions first appeared in
.\" 4.4BSD.
.SH SEE ALSO
.BR error (3),
.BR exit (3),
.BR printf (3),
.BR perror (3),
.BR strerror (3)
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