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.Dd March 29, 2012 29.Dt ERR 3 30.Os 31.Sh NAME 32.Nm err , 33.Nm verr , 34.Nm errc , 35.Nm verrc , 36.Nm errx , 37.Nm verrx , 38.Nm warn , 39.Nm vwarn , 40.Nm warnc , 41.Nm vwarnc , 42.Nm warnx , 43.Nm vwarnx , 44.Nm err_set_exit , 45.Nm err_set_file 46.Nd formatted error messages 47.Sh LIBRARY 48.Lb libc 49.Sh SYNOPSIS 50.In err.h 51.Ft void 52.Fn err "int eval" "const char *fmt" "..." 53.Ft void 54.Fn err_set_exit "void (*exitf)(int)" 55.Ft void 56.Fn err_set_file "void *vfp" 57.Ft void 58.Fn errc "int eval" "int code" "const char *fmt" "..." 59.Ft void 60.Fn errx "int eval" "const char *fmt" "..." 61.Ft void 62.Fn warn "const char *fmt" "..." 63.Ft void 64.Fn warnc "int code" "const char *fmt" "..." 65.Ft void 66.Fn warnx "const char *fmt" "..." 67.In stdarg.h 68.Ft void 69.Fn verr "int eval" "const char *fmt" "va_list args" 70.Ft void 71.Fn verrc "int eval" "int code" "const char *fmt" "va_list args" 72.Ft void 73.Fn verrx "int eval" "const char *fmt" "va_list args" 74.Ft void 75.Fn vwarn "const char *fmt" "va_list args" 76.Ft void 77.Fn vwarnc "int code" "const char *fmt" "va_list args" 78.Ft void 79.Fn vwarnx "const char *fmt" "va_list args" 80.Sh DESCRIPTION 81The 82.Fn err 83and 84.Fn warn 85family of functions display a formatted error message on the standard 86error output, or on another file specified using the 87.Fn err_set_file 88function. 89In all cases, the last component of the program name, a colon character, 90and a space are output. 91If the 92.Fa fmt 93argument is not NULL, the 94.Xr printf 3 Ns 95-like formatted error message is output. 96The output is terminated by a newline character. 97.Pp 98The 99.Fn err , 100.Fn errc , 101.Fn verr , 102.Fn verrc , 103.Fn warn , 104.Fn warnc , 105.Fn vwarn , 106and 107.Fn vwarnc 108functions append an error message obtained from 109.Xr strerror 3 110based on a supplied error code value or the global variable 111.Va errno , 112preceded by another colon and space unless the 113.Fa fmt 114argument is 115.Dv NULL . 116.Pp 117In the case of the 118.Fn errc , 119.Fn verrc , 120.Fn warnc , 121and 122.Fn vwarnc 123functions, 124the 125.Fa code 126argument is used to look up the error message. 127.Pp 128The 129.Fn err , 130.Fn verr , 131.Fn warn , 132and 133.Fn vwarn 134functions use the global variable 135.Va errno 136to look up the error message. 137.Pp 138The 139.Fn errx 140and 141.Fn warnx 142functions do not append an error message. 143.Pp 144The 145.Fn err , 146.Fn verr , 147.Fn errc , 148.Fn verrc , 149.Fn errx , 150and 151.Fn verrx 152functions do not return, but exit with the value of the argument 153.Fa eval . 154It is recommended that the standard values defined in 155.Xr sysexits 3 156be used for the value of 157.Fa eval . 158The 159.Fn err_set_exit 160function can be used to specify a function which is called before 161.Xr exit 3 162to perform any necessary cleanup; passing a null function pointer for 163.Va exitf 164resets the hook to do nothing. 165The 166.Fn err_set_file 167function sets the output stream used by the other functions. 168Its 169.Fa vfp 170argument must be either a pointer to an open stream 171(possibly already converted to void *) 172or a null pointer 173(in which case the output stream is set to standard error). 174.Sh EXAMPLES 175Display the current errno information string and exit: 176.Bd -literal -offset indent 177if ((p = malloc(size)) == NULL) 178 err(EX_OSERR, NULL); 179if ((fd = open(file_name, O_RDONLY, 0)) == -1) 180 err(EX_NOINPUT, "%s", file_name); 181.Ed 182.Pp 183Display an error message and exit: 184.Bd -literal -offset indent 185if (tm.tm_hour < START_TIME) 186 errx(EX_DATAERR, "too early, wait until %s", 187 start_time_string); 188.Ed 189.Pp 190Warn of an error: 191.Bd -literal -offset indent 192if ((fd = open(raw_device, O_RDONLY, 0)) == -1) 193 warnx("%s: %s: trying the block device", 194 raw_device, strerror(errno)); 195if ((fd = open(block_device, O_RDONLY, 0)) == -1) 196 err(EX_OSFILE, "%s", block_device); 197.Ed 198.Pp 199Warn of an error without using the global variable 200.Va errno : 201.Bd -literal -offset indent 202error = my_function(); /* returns a value from <errno.h> */ 203if (error != 0) 204 warnc(error, "my_function"); 205.Ed 206.Sh SEE ALSO 207.Xr exit 3 , 208.Xr fmtmsg 3 , 209.Xr printf 3 , 210.Xr strerror 3 , 211.Xr sysexits 3 212.Sh STANDARDS 213The 214.Fn err 215and 216.Fn warn 217families of functions are 218.Bx 219extensions. 220As such they should not be used in truly portable code. 221Use 222.Fn strerror 223or similar functions instead. 224.Sh HISTORY 225The 226.Fn err 227and 228.Fn warn 229functions first appeared in 230.Bx 4.4 . 231The 232.Fn err_set_exit 233and 234.Fn err_set_file 235functions first appeared in 236.Fx 2.1 . 237The 238.Fn errc 239and 240.Fn warnc 241functions first appeared in 242.Fx 3.0 . 243