1.\" Copyright (c) 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" From: @(#)err.3 8.1 (Berkeley) 6/9/93 29.\" $FreeBSD: src/lib/libc/gen/err.3,v 1.24 2008/10/31 15:14:40 rwatson Exp $ 30.\" 31.Dd March 6, 1999 32.Dt ERR 3 33.Os 34.Sh NAME 35.Nm err , 36.Nm verr , 37.Nm errc , 38.Nm verrc , 39.Nm errx , 40.Nm verrx , 41.Nm warn , 42.Nm vwarn , 43.Nm warnc , 44.Nm vwarnc , 45.Nm warnx , 46.Nm vwarnx , 47.Nm err_set_exit , 48.Nm err_set_file 49.Nd formatted error messages 50.Sh LIBRARY 51.Lb libc 52.Sh SYNOPSIS 53.In err.h 54.Ft void 55.Fn err "int eval" "const char *fmt" "..." 56.Ft void 57.Fn err_set_exit "void (*exitf)(int)" 58.Ft void 59.Fn err_set_file "void *vfp" 60.Ft void 61.Fn errc "int eval" "int code" "const char *fmt" "..." 62.Ft void 63.Fn errx "int eval" "const char *fmt" "..." 64.Ft void 65.Fn warn "const char *fmt" "..." 66.Ft void 67.Fn warnc "int code" "const char *fmt" "..." 68.Ft void 69.Fn warnx "const char *fmt" "..." 70.In stdarg.h 71.Ft void 72.Fn verr "int eval" "const char *fmt" "va_list args" 73.Ft void 74.Fn verrc "int eval" "int code" "const char *fmt" "va_list args" 75.Ft void 76.Fn verrx "int eval" "const char *fmt" "va_list args" 77.Ft void 78.Fn vwarn "const char *fmt" "va_list args" 79.Ft void 80.Fn vwarnc "int code" "const char *fmt" "va_list args" 81.Ft void 82.Fn vwarnx "const char *fmt" "va_list args" 83.Sh DESCRIPTION 84The 85.Fn err 86and 87.Fn warn 88family of functions display a formatted error message on the standard 89error output, or on another file specified using the 90.Fn err_set_file 91function. 92In all cases, the last component of the program name, a colon character, 93and a space are output. 94If the 95.Fa fmt 96argument is not NULL, the 97.Xr printf 3 Ns 98-like formatted error message is output. 99The output is terminated by a newline character. 100.Pp 101The 102.Fn err , 103.Fn errc , 104.Fn verr , 105.Fn verrc , 106.Fn warn , 107.Fn warnc , 108.Fn vwarn , 109and 110.Fn vwarnc 111functions append an error message obtained from 112.Xr strerror 3 113based on a supplied error code value or the global variable 114.Va errno , 115preceded by another colon and space unless the 116.Fa fmt 117argument is 118.Dv NULL . 119.Pp 120In the case of the 121.Fn errc , 122.Fn verrc , 123.Fn warnc , 124and 125.Fn vwarnc 126functions, 127the 128.Fa code 129argument is used to look up the error message. 130.Pp 131The 132.Fn err , 133.Fn verr , 134.Fn warn , 135and 136.Fn vwarn 137functions use the global variable 138.Va errno 139to look up the error message. 140.Pp 141The 142.Fn errx , 143.Fn verrx , 144.Fn warnx , 145and 146.Fn vwarnx 147functions do not append an error message. 148.Pp 149The 150.Fn err , 151.Fn verr , 152.Fn errc , 153.Fn verrc , 154.Fn errx , 155and 156.Fn verrx 157functions do not return, but exit with the value of the argument 158.Fa eval . 159It is recommended that the standard values defined in 160.Xr sysexits 3 161be used for the value of 162.Fa eval . 163The 164.Fn err_set_exit 165function can be used to specify a function which is called before 166.Xr exit 3 167to perform any necessary cleanup; passing a null function pointer for 168.Va exitf 169resets the hook to do nothing. 170The 171.Fn err_set_file 172function sets the output stream used by the other functions. 173Its 174.Fa vfp 175argument must be either a pointer to an open stream 176(possibly already converted to void *) 177or a null pointer 178(in which case the output stream is set to standard error). 179.Sh EXAMPLES 180Display the current 181.Va errno 182information string and exit: 183.Bd -literal -offset indent 184if ((p = malloc(size)) == NULL) 185 err(EX_OSERR, NULL); 186if ((fd = open(file_name, O_RDONLY, 0)) == -1) 187 err(EX_NOINPUT, "%s", file_name); 188.Ed 189.Pp 190Display an error message and exit: 191.Bd -literal -offset indent 192if (tm.tm_hour < START_TIME) 193 errx(EX_DATAERR, "too early, wait until %s", 194 start_time_string); 195.Ed 196.Pp 197Warn of an error: 198.Bd -literal -offset indent 199if ((fd = open(raw_device, O_RDONLY, 0)) == -1) 200 warnx("%s: %s: trying the block device", 201 raw_device, strerror(errno)); 202if ((fd = open(block_device, O_RDONLY, 0)) == -1) 203 err(EX_OSFILE, "%s", block_device); 204.Ed 205.Pp 206Warn of an error without using the global variable 207.Va errno : 208.Bd -literal -offset indent 209error = my_function(); /* returns a value from <errno.h> */ 210if (error != 0) 211 warnc(error, "my_function"); 212.Ed 213.Sh SEE ALSO 214.Xr exit 3 , 215.Xr fmtmsg 3 , 216.Xr printf 3 , 217.Xr strerror 3 , 218.Xr sysexits 3 219.Sh HISTORY 220The 221.Fn err 222and 223.Fn warn 224functions first appeared in 225.Bx 4.4 . 226The 227.Fn err_set_exit 228and 229.Fn err_set_file 230functions first appeared in 231.Fx 2.1 . 232The 233.Fn errc 234and 235.Fn warnc 236functions first appeared in 237.Fx 3.0 . 238