ERR(3) | Library Functions Manual | ERR(3) |
err
, verr
,
errc
, verrc
,
errx
, verrx
,
warn
, vwarn
,
warnc
, vwarnc
,
warnx
, vwarnx
,
err_set_exit
,
err_set_exit_b
, err_set_file
— formatted error messages
Standard C Library (libc, -lc)
#include
<err.h>
void
err
(int
eval, const char
*fmt, ...);
void
err_set_exit
(void
(*exitf)(int));
void
err_set_exit_b
(void
(^exitb)(int));
void
err_set_file
(void
*vfp);
void
errc
(int
eval, int code,
const char *fmt,
...);
void
errx
(int
eval, const char
*fmt, ...);
void
warn
(const
char *fmt,
...);
void
warnc
(int
code, const char
*fmt, ...);
void
warnx
(const
char *fmt,
...);
#include
<stdarg.h>
void
verr
(int
eval, const char
*fmt, va_list
args);
void
verrc
(int
eval, int code,
const char *fmt,
va_list args);
void
verrx
(int
eval, const char
*fmt, va_list
args);
void
vwarn
(const
char *fmt, va_list
args);
void
vwarnc
(int
code, const char
*fmt, va_list
args);
void
vwarnx
(const
char *fmt, va_list
args);
The
err
()
and
warn
()
family of functions display a formatted error message on the standard error
output, or on another file specified using the
err_set_file
() function. In all cases, the last
component of the program name, a colon character, and a space are output. If
the fmt argument is not NULL, the
printf(3)-like formatted error message
is output. The output is terminated by a newline character.
The
err
(),
errc
(), verr
(),
verrc
(), warn
(),
warnc
(), vwarn
(), and
vwarnc
() functions append an error message obtained
from strerror(3) based on a supplied
error code value or the global variable errno,
preceded by another colon and space unless the fmt
argument is NULL
.
In the case of the
errc
(),
verrc
(),
warnc
(),
and
vwarnc
()
functions, the code argument is used to look up the
error message.
The
err
(),
verr
(),
warn
(), and
vwarn
()
functions use the global variable errno to look up the
error message.
The
errx
() and
warnx
()
functions do not append an error message.
The
err
(),
verr
(),
errc
(), verrc
(),
errx
(), and
verrx
()
functions do not return, but exit with the value of the argument
eval. It is recommended that the standard values
defined in sysexits(3) be used for
the value of eval. The
err_set_exit
()
function can be used to specify a function which is called before
exit(3) to perform any necessary cleanup;
passing a null function pointer for exitf resets the
hook to do nothing. The
err_set_exit_b
()
function is like err_set_exit
() except it takes a
block pointer instead of a function pointer.
Block_copy
()
function (defined in
<Blocks.h>
) is used by
err_set_exit_b
() to make a copy of the block,
especially for the case when a stack-based block might go out of scope when
the subroutine returns.The
err_set_file
()
function sets the output stream used by the other functions. Its
vfp argument must be either a pointer to an open
stream (possibly already converted to void *) or a null pointer (in which
case the output stream is set to standard error).
Display the current errno information string and exit:
if ((p = malloc(size)) == NULL) err(EX_OSERR, NULL); if ((fd = open(file_name, O_RDONLY, 0)) == -1) err(EX_NOINPUT, "%s", file_name);
Display an error message and exit:
if (tm.tm_hour < START_TIME) errx(EX_DATAERR, "too early, wait until %s", start_time_string);
Warn of an error:
if ((fd = open(raw_device, O_RDONLY, 0)) == -1) warnx("%s: %s: trying the block device", raw_device, strerror(errno)); if ((fd = open(block_device, O_RDONLY, 0)) == -1) err(EX_OSFILE, "%s", block_device);
Warn of an error without using the global variable errno:
error = my_function(); /* returns a value from <errno.h> */ if (error != 0) warnc(error, "my_function");
The err
() and
warn
() functions first appeared in
4.4BSD. The err_set_exit
()
and err_set_file
() functions first appeared in
FreeBSD 2.1. The errc
() and
warnc
() functions first appeared in
FreeBSD 3.0. The
err_set_exit_b
() function first appeared in Mac OS X
10.6.
May 20, 2008 | macOS 14.6 |