#include <err.h> noreturn void err(int eval, const char *fmt, ...); noreturn void errx(int eval, const char *fmt, ...); void warn(const char *fmt, ...); void warnx(const char *fmt, ...); #include <stdarg.h> noreturn void verr(int eval, const char *fmt, va_list args); noreturn 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(), 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.
| Interface | Attribute | Value |
| err(), errx(), warn(), warnx(), verr(), verrx(), vwarn(), vwarnx() | Thread safety | MT-Safe locale |
p = malloc(size);
if (p == NULL)
err(EXIT_FAILURE, NULL);
fd = open(file_name, O_RDONLY, 0);
if (fd == -1)
err(EXIT_FAILURE, "%s", file_name);
Display an error message and exit:
if (tm.tm_hour < START_TIME)
errx(EXIT_FAILURE, "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(EXIT_FAILURE, "%s", block_device);