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