ERR(3)                    OpenBSD 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, followed by a colon (`:') character and a space, are
     output.  The text that follows depends on the function being called.  The
     fmt specification (and associated arguments) may be any format allowed by
     printf(3) or a simple string.

     In the case of the err(), verr(), warn(), and vwarn() functions only, the
     error message string affiliated with the current value of the global
     variable errno is output (see strerror(3));  that is, the output is as
     follows:

           progname: fmt: error message string

     The counterpart functions, errx(), verrx(), warnx(), and vwarnx(), do not
     output the error message string, so the output looks like the following:

           progname: fmt

     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, 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);

SEE ALSO
     exit(3),  perror(3),  printf(3),  strerror(3)

HISTORY
     The err() and warn() functions first appeared in 4.4BSD.

OpenBSD 2.6                     August 8, 1997                               2