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.\" 30.Dd March 29, 2012 31.Dt ERR 3 32.Os 33.Sh NAME 34.Nm err , 35.Nm verr , 36.Nm errc , 37.Nm verrc , 38.Nm errx , 39.Nm verrx , 40.Nm warn , 41.Nm vwarn , 42.Nm warnc , 43.Nm vwarnc , 44.Nm warnx , 45.Nm vwarnx , 46.Nm err_set_exit , 47.Nm err_set_file 48.Nd formatted error messages 49.Sh LIBRARY 50.Lb libc 51.Sh SYNOPSIS 52.In err.h 53.Ft void 54.Fn err "int eval" "const char *fmt" "..." 55.Ft void 56.Fn err_set_exit "void (*exitf)(int)" 57.Ft void 58.Fn err_set_file "void *vfp" 59.Ft void 60.Fn errc "int eval" "int code" "const char *fmt" "..." 61.Ft void 62.Fn errx "int eval" "const char *fmt" "..." 63.Ft void 64.Fn warn "const char *fmt" "..." 65.Ft void 66.Fn warnc "int code" "const char *fmt" "..." 67.Ft void 68.Fn warnx "const char *fmt" "..." 69.In stdarg.h 70.Ft void 71.Fn verr "int eval" "const char *fmt" "va_list args" 72.Ft void 73.Fn verrc "int eval" "int code" "const char *fmt" "va_list args" 74.Ft void 75.Fn verrx "int eval" "const char *fmt" "va_list args" 76.Ft void 77.Fn vwarn "const char *fmt" "va_list args" 78.Ft void 79.Fn vwarnc "int code" "const char *fmt" "va_list args" 80.Ft void 81.Fn vwarnx "const char *fmt" "va_list args" 82.Sh DESCRIPTION 83The 84.Fn err 85and 86.Fn warn 87family of functions display a formatted error message on the standard 88error output, or on another file specified using the 89.Fn err_set_file 90function. 91In all cases, the last component of the program name, a colon character, 92and a space are output. 93If the 94.Fa fmt 95argument is not NULL, the 96.Xr printf 3 Ns 97-like formatted error message is output. 98The output is terminated by a newline character. 99.Pp 100The 101.Fn err , 102.Fn errc , 103.Fn verr , 104.Fn verrc , 105.Fn warn , 106.Fn warnc , 107.Fn vwarn , 108and 109.Fn vwarnc 110functions append an error message obtained from 111.Xr strerror 3 112based on a supplied error code value or the global variable 113.Va errno , 114preceded by another colon and space unless the 115.Fa fmt 116argument is 117.Dv NULL . 118.Pp 119In the case of the 120.Fn errc , 121.Fn verrc , 122.Fn warnc , 123and 124.Fn vwarnc 125functions, 126the 127.Fa code 128argument is used to look up the error message. 129.Pp 130The 131.Fn err , 132.Fn verr , 133.Fn warn , 134and 135.Fn vwarn 136functions use the global variable 137.Va errno 138to look up the error message. 139.Pp 140The 141.Fn errx 142and 143.Fn warnx 144functions do not append an error message. 145.Pp 146The 147.Fn err , 148.Fn verr , 149.Fn errc , 150.Fn verrc , 151.Fn errx , 152and 153.Fn verrx 154functions do not return, but exit with the value of the argument 155.Fa eval . 156It is recommended that the standard values defined in 157.Xr sysexits 3 158be used for the value of 159.Fa eval . 160The 161.Fn err_set_exit 162function can be used to specify a function which is called before 163.Xr exit 3 164to perform any necessary cleanup; passing a null function pointer for 165.Va exitf 166resets the hook to do nothing. 167The 168.Fn err_set_file 169function sets the output stream used by the other functions. 170Its 171.Fa vfp 172argument must be either a pointer to an open stream 173(possibly already converted to void *) 174or a null pointer 175(in which case the output stream is set to standard error). 176.Sh EXAMPLES 177Display the current errno information string and exit: 178.Bd -literal -offset indent 179if ((p = malloc(size)) == NULL) 180 err(EX_OSERR, NULL); 181if ((fd = open(file_name, O_RDONLY, 0)) == -1) 182 err(EX_NOINPUT, "%s", file_name); 183.Ed 184.Pp 185Display an error message and exit: 186.Bd -literal -offset indent 187if (tm.tm_hour < START_TIME) 188 errx(EX_DATAERR, "too early, wait until %s", 189 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(EX_OSFILE, "%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 fmtmsg 3 , 211.Xr printf 3 , 212.Xr strerror 3 , 213.Xr sysexits 3 214.Sh STANDARDS 215The 216.Fn err 217and 218.Fn warn 219families of functions are 220.Bx 221extensions. 222As such they should not be used in truly portable code. 223Use 224.Fn strerror 225or similar functions instead. 226.Sh HISTORY 227The 228.Fn err 229and 230.Fn warn 231functions first appeared in 232.Bx 4.4 . 233The 234.Fn err_set_exit 235and 236.Fn err_set_file 237functions first appeared in 238.Fx 2.1 . 239The 240.Fn errc 241and 242.Fn warnc 243functions first appeared in 244.Fx 3.0 . 245