3688be0eeb
programs which use err(3) to work nicely in a wider range of environments (e.g., dialog).
145 lines
4.3 KiB
Groff
145 lines
4.3 KiB
Groff
.\" Copyright (c) 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" From: @(#)err.3 8.1 (Berkeley) 6/9/93
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.\" $Id$
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.\"
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.Dd April 13, 1995
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.Dt ERR 3
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.Os BSD 4
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.Sh NAME
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.Nm err ,
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.Nm verr ,
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.Nm errx ,
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.Nm verrx ,
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.Nm warn ,
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.Nm vwarn ,
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.Nm warnx ,
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.Nm vwarnx ,
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.Nm err_set_file ,
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.Nm err_set_exit
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.Nd formatted error messages
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.Sh SYNOPSIS
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.Fd #include <err.h>
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.Ft void
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.Fn err "int eval" "const char *fmt" "..."
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.Ft void
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.Fn verr "int eval" "const char *fmt" "va_list args"
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.Ft void
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.Fn errx "int eval" "const char *fmt" "..."
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.Ft void
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.Fn verrx "int eval" "const char *fmt" "va_list args"
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.Ft void
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.Fn warn "const char *fmt" "..."
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.Ft void
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.Fn vwarn "const char *fmt" "va_list args"
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.Ft void
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.Fn warnx "const char *fmt" "..."
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.Ft void
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.Fn vwarnx "const char *fmt" "va_list args"
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.Ft void
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.Fn err_set_file "void *fp"
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.Ft void
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.Fn err_set_exit "void (*exitf)(int)"
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.Sh DESCRIPTION
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The
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.Fn err
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and
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.Fn warn
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family of functions display a formatted error message on the standard
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error output, or on another file specified using the
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.Fn err_set_file
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function.
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In all cases, the last component of the program name, a colon character,
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and a space are output.
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If the
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.Va fmt
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argument is not NULL, the formatted error message, a colon character,
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and a space are output.
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In the case of the
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.Fn err ,
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.Fn verr ,
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.Fn warn ,
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and
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.Fn vwarn
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functions, the error message string affiliated with the current value of
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the global variable
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.Va errno
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is output.
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In all cases, the output is followed by a newline character.
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.Pp
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The
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.Fn err ,
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.Fn verr ,
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.Fn errx ,
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and
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.Fn verrx
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functions do not return, but exit with the value of the argument
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.Fa eval .
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The
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.Fn err_set_exit
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function can be used to specify a function which is called before
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.Xr exit 2
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to perform any necessary cleanup; passing a null function pointer for
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.Va exitf
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resets the hook to do nothing.
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.Sh EXAMPLES
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Display the current errno information string and exit:
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.Bd -literal -offset indent
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if ((p = malloc(size)) == NULL)
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err(1, NULL);
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if ((fd = open(file_name, O_RDONLY, 0)) == -1)
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err(1, "%s", file_name);
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.Ed
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.Pp
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Display an error message and exit:
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.Bd -literal -offset indent
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if (tm.tm_hour < START_TIME)
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errx(1, "too early, wait until %s", start_time_string);
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.Ed
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.Pp
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Warn of an error:
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.Bd -literal -offset indent
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if ((fd = open(raw_device, O_RDONLY, 0)) == -1)
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warnx("%s: %s: trying the block device",
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raw_device, strerror(errno));
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if ((fd = open(block_device, O_RDONLY, 0)) == -1)
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err(1, "%s", block_device);
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.Ed
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.Sh SEE ALSO
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.Xr strerror 3
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.Sh HISTORY
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The
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.Fn err
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and
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.Fn warn
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functions first appeared in 4.4BSD.
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