ERR(3) MachTen Programmer’s Manual ERR(3)

NAME
err, verr, errx, verrx, warn, vwarn, warnx, vwarnx - formatted error mes-
sages

SYNOPSIS
#include <err.h>

void
err(int eval, const char *fmt, ...)

void
verr(int eval, const char *fmt, va_list args)

void
errx(int eval, const char *fmt, ...)

void
verrx(int eval, const char *fmt, va_list args)

void
warn(const char *fmt, ...)

void
vwarn(const char *fmt, va_list args)

void
warnx(const char *fmt, ...)

void
vwarnx(const char *fmt, va_list args)

DESCRIPTION
The err() and warn() family of functions display a formatted error mes-
sage 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 formatted error message, a colon character, and
a space are output. In the case of the err(), verr(), warn(), and
vwarn() functions, the error message string affiliated with the current
value of the global variable errno is output. In all cases, the output
is followed by a newline character.

The err(), verr(), errx(), and verrx() functions do not return, but exit
with the value of the argument eval.

EXAMPLES
Display the current errno information string and exit:

if ((p = malloc(size)) == NULL)
err(1, NULL);
if ((fd = open(file_name, O_RDONLY, 0)) == -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:

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(1, "%s", block_device);