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libc/gen/err.[3c]: New files
This commit is contained in:
Joel Sherrill
233
freebsd-userspace/lib/libc/gen/err.3
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233
freebsd-userspace/lib/libc/gen/err.3
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.\" 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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.\" 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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.\" $FreeBSD$
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.\"
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.Dd March 6, 1999
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.Dt ERR 3
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.Os
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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_exit ,
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.Nm err_set_file
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.Nd formatted error messages
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In 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 err_set_exit "void (*exitf)(int)"
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.Ft void
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.Fn err_set_file "void *vfp"
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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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.In 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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.Fa fmt
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argument is not NULL, the
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.Xr printf 3 Ns
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-like formatted error message is output.
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The output is terminated 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 errc ,
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.Fn verr ,
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.Fn verrc ,
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.Fn warn ,
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.Fn warnc ,
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.Fn vwarn ,
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and
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.Fn vwarnc
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functions append an error message obtained from
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.Xr strerror 3
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based on a supplied error code value or the global variable
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.Va errno ,
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preceded by another colon and space unless the
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.Fa fmt
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argument is
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.Dv NULL .
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.Pp
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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
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.Fa code
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argument is used to look up the error message.
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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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to look up the error message.
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.Pp
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The
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.Fn errx
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and
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.Fn warnx
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functions do not append an error message.
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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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It is recommended that the standard values defined in
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.Xr sysexits 3
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be used for the value of
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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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The
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.Fn err_set_file
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function sets the output stream used by the other functions.
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Its
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.Fa vfp
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argument must be either a pointer to an open stream
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(possibly already converted to void *)
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or a null pointer
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(in which case the output stream is set to standard error).
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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(EX_OSERR, NULL);
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if ((fd = open(file_name, O_RDONLY, 0)) == -1)
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err(EX_NOINPUT, "%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(EX_DATAERR, "too early, wait until %s",
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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(EX_OSFILE, "%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 fmtmsg 3 ,
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.Xr printf 3 ,
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.Xr strerror 3 ,
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.Xr sysexits 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_exit
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and
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.Fn err_set_file
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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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