NAME

       err, verr, errx, verrx, warn, vwarn, warnx, vwarnx - formatted error messages

SYNOPSIS

       #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);

DESCRIPTION

       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.

CONFORMING TO

       These functions are nonstandard BSD extensions.

EXAMPLE

       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);

SEE ALSO

       error(3), exit(3), perror(3), printf(3), strerror(3)

COLOPHON

       This page is part of release 3.54 of the Linux man-pages project.  A  description  of  the  project,  and
       information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.