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ERR(3)		       FreeBSD Library Functions Manual			ERR(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
     err_set_file() function.  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(),	errc(),	verr(),	verrc(), warn(), warnc(), vwarn(), and
     vwarnc() functions	append an error	message	obtained from strerror(3)
     based on a	code or	the global variable errno, preceded by another colon
     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	9.2			 March 6, 1999			   FreeBSD 9.2

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | HISTORY

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