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 117If the kernel returned an extended error string in addition to the 118.Va errno 119code, the 120.Fn err 121function prints the string with interpolated values for parameters, 122as provided to the corresponding invocation of 123.Xr EXTERROR 9 . 124If the extended error string was not provided, but extended error 125information was, or even if string was provided and the 126.Ev EXTERROR_VERBOSE 127environment variable is present, an additional report is printed. 128The report includes at least the category of the error, the name of 129the source file (if known by the used version of libc), 130the source line number, and parameters. 131The format of the printed string is not contractual and might be changed. 132.Pp 133In the case of the 134.Fn errc , 135.Fn verrc , 136.Fn warnc , 137and 138.Fn vwarnc 139functions, 140the 141.Fa code 142argument is used to look up the error message. 143.Pp 144The 145.Fn err , 146.Fn verr , 147.Fn warn , 148and 149.Fn vwarn 150functions use the global variable 151.Va errno 152to look up the error message. 153.Pp 154The 155.Fn errx 156and 157.Fn warnx 158functions do not append an error message. 159.Pp 160The 161.Fn err , 162.Fn verr , 163.Fn errc , 164.Fn verrc , 165.Fn errx , 166and 167.Fn verrx 168functions do not return, but exit with the value of the argument 169.Fa eval . 170It is recommended that the standard values defined in 171.Xr sysexits 3 172be used for the value of 173.Fa eval . 174The 175.Fn err_set_exit 176function can be used to specify a function which is called before 177.Xr exit 3 178to perform any necessary cleanup; passing a null function pointer for 179.Va exitf 180resets the hook to do nothing. 181The 182.Fn err_set_file 183function sets the output stream used by the other functions. 184Its 185.Fa vfp 186argument must be either a pointer to an open stream 187(possibly already converted to void *) 188or a null pointer 189(in which case the output stream is set to standard error). 190.Sh EXAMPLES 191Display the current errno information string and exit: 192.Bd -literal -offset indent 193if ((p = malloc(size)) == NULL) 194 err(EX_OSERR, NULL); 195if ((fd = open(file_name, O_RDONLY, 0)) == -1) 196 err(EX_NOINPUT, "%s", file_name); 197.Ed 198.Pp 199Display an error message and exit: 200.Bd -literal -offset indent 201if (tm.tm_hour < START_TIME) 202 errx(EX_DATAERR, "too early, wait until %s", 203 start_time_string); 204.Ed 205.Pp 206Warn of an error: 207.Bd -literal -offset indent 208if ((fd = open(raw_device, O_RDONLY, 0)) == -1) 209 warnx("%s: %s: trying the block device", 210 raw_device, strerror(errno)); 211if ((fd = open(block_device, O_RDONLY, 0)) == -1) 212 err(EX_OSFILE, "%s", block_device); 213.Ed 214.Pp 215Warn of an error without using the global variable 216.Va errno : 217.Bd -literal -offset indent 218error = my_function(); /* returns a value from <errno.h> */ 219if (error != 0) 220 warnc(error, "my_function"); 221.Ed 222.Sh SEE ALSO 223.Xr exit 3 , 224.Xr fmtmsg 3 , 225.Xr printf 3 , 226.Xr strerror 3 , 227.Xr sysexits 3 228.Sh STANDARDS 229The 230.Fn err 231and 232.Fn warn 233families of functions are 234.Bx 235extensions. 236As such they should not be used in truly portable code. 237Use 238.Fn strerror 239or similar functions instead. 240.Sh HISTORY 241The 242.Fn err 243and 244.Fn warn 245functions first appeared in 246.Bx 4.4 . 247The 248.Fn err_set_exit 249and 250.Fn err_set_file 251functions first appeared in 252.Fx 2.1 . 253The 254.Fn errc 255and 256.Fn warnc 257functions first appeared in 258.Fx 3.0 . 259