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vwarn(3)

NAME

     err, verr, errc, verrc, errx, verrx, warn, vwarn, warnc, vwarnc, warnx,
     vwarnx, err_set_exit, err_set_file -- formatted error messages

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <err.h>

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

     void
     err_set_exit(void (*exitf)(int));

     void
     err_set_file(void *vfp);

     void
     errc(int eval, int code, const char *fmt, ...);

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

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

     void
     warnc(int code, const char *fmt, ...);

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

     #include <stdarg.h>

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

     void
     verrc(int eval, int code, 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
     vwarnc(int code, 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 mes-
     sage on the standard error output, or on another file specified using the
     and space unless the fmt argument is NULL.

     In the case of the errc(), verrc(), warnc(), and vwarnc() functions, the
     code argument is used to look up the error message.

     The err(), verr(), warn(), and vwarn() functions use the global variable
     errno to look up the error message.

     The errx() and warnx() functions do not append an error message.

     The err(), verr(), errc(), verrc(), errx(), and verrx() functions do not
     return, but exit with the value of the argument eval.  The err_set_exit()
     function can be used to specify a function which is called before exit(3)
     to perform any necessary cleanup; passing a null function pointer for
     exitf resets the hook to do nothing.  The err_set_file() function sets
     the output stream used by the other functions.  Its vfp argument must be
     either a pointer to an open stream (possibly already converted to void *)
     or a null pointer (in which case the output stream is set to standard
     error).

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);

     Warn of an error without using the global variable errno:

	   error = my_function();  /* returns a value from <errno.h> */
	   if (error != 0)
		   warnc(error, "my_function");

SEE ALSO

     exit(3), fmtmsg(3), printf(3), strerror(3)

HISTORY

     The err() and warn() functions first appeared in 4.4BSD.  The
     err_set_exit() and err_set_file() functions first appeared in
     FreeBSD 2.1.  The errc() and warnc() functions first appeared in
     FreeBSD 3.0.

FreeBSD 5.4			 March 6, 1999			   FreeBSD 5.4

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