err, verr, errx, verrx, warn, vwarn, warnx, vwarnx - formatted error messages
#include <err.h>
void err(int eval, const char *fmt, ...);
void errx(int eval, const char *fmt, ...);
void warn(const char *fmt, ...);
void warnx(const char *fmt, ...);
#include <stdarg.h>
void verr(int eval, 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 vwarnx(const char *fmt, va_list args);
The
err() and
warn() family of functions display a formatted error
message on the standard error output. 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(),
verr(),
warn(), and
vwarn() functions
append an error message obtained from
strerror(3) based on the global
variable
errno, preceded by another colon and space unless the
fmt argument is NULL.
The
errx() and
warnx() functions do not append an error message.
The
err(),
verr(),
errx(), and
verrx() functions do
not return, but exit with the value of the argument
eval.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
err (), errx (), warn (), warnx (), verr (), verrx (), vwarn (), vwarnx
() |
Thread safety |
MT-Safe locale |
These functions are nonstandard BSD extensions.
Display the current
errno information string and exit:
p = malloc(size);
if (p == NULL)
err(1, NULL);
fd = open(file_name, O_RDONLY, 0);
if (fd == -1)
err(1, "%s", file_name);
Display an error message and exit:
if (tm.tm_hour < START_TIME)
errx(1, "too early, wait until %s", start_time_string);
Warn of an error:
fd = open(raw_device, O_RDONLY, 0);
if (fd == -1)
warnx("%s: %s: trying the block device",
raw_device, strerror(errno));
fd = open(block_device, O_RDONLY, 0);
if (fd == -1)
err(1, "%s", block_device);
error(3),
exit(3),
perror(3),
printf(3),
strerror(3)