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b4b4fb871e
- Fix some style errors I made back in 1995. - Add a new flavor of the err(3) family, which takes an explicit errno argument rather than implicitly examining errno. This will make it easier to use these functions in conjunction with modern library interfaces that return an errno value explicitly.
197 lines
5.2 KiB
Groff
197 lines
5.2 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: err.3,v 1.8 1998/04/22 19:59:55 rnordier Exp $
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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 errc ,
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.Nm verrc ,
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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 warnc ,
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.Nm vwarnc ,
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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 errc "int eval" "int code" "const char *fmt" "..."
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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 warn "const char *fmt" "..."
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.Ft void
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.Fn warnc "int code" "const char *fmt" "..."
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.Ft void
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.Fn warnx "const char *fmt" "..."
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.Fd #include <stdio.h>
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.Ft void
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.Fn err_set_file "FILE *fp"
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.Ft void
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.Fn err_set_exit "void (*exitf)(int)"
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.Fd #include <stdarg.h>
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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 verrc "int eval" "int code" "const char *fmt" "va_list args"
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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 vwarn "const char *fmt" "va_list args"
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.Ft void
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.Fn vwarnc "int code" "const char *fmt" "va_list args"
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.Ft void
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.Fn vwarnx "const char *fmt" "va_list args"
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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 is output.
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In the case of the
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.Fn errc ,
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.Fn verrc ,
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.Fn warnc ,
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and
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.Fn vwarnc
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functions,
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the error message string affiliated with the
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.Va code
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argument is also output,
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preceded by another colon and space if necessary.
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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 warn ,
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and
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.Fn vwarn
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functions use the global variable
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.Va errno
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rather than the
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.Va code
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argument of the
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.Fn errc
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family
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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 errc ,
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.Fn verrc ,
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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 3
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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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.Pp
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Warn of an error without using the global variable
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.Va errno :
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.Bd -literal -offset indent
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error = my_function(); /* returns a value from <errno.h> */
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if (error != 0)
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warnc(error, "my_function");
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.Ed
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.Sh SEE ALSO
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.Xr exit 3 ,
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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
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.Bx 4.4 .
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The
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.Fn err_set_file
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and
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.Fn err_set_exit
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functions first appeared in
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.Fx 2.1 .
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The
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.Fn errc
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and
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.Fn warnc
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functions first appeared in
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.Fx 3.0 .
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