#include <syslog.h>
#include <stdarg.h>

void vsyslog(int priority, const char *message, va_list ap);

The vsyslog() function is identical to syslog(3C), except that it is called with an argument list as defined by <stdarg.h> rather than with a variable number of arguments.

Example 1 Use vsyslog() to write an error routine.

The following example demonstrates the use of vsyslog() in writing an error routine.

#include <syslog.h>
#include <stdarg.h>
 
/*
 * error should be called like:
 * error(pri, function_name, format, arg1, arg2...);
 */

void
error(int pri, char *function_name, char *format, ...)
{
 va_list args;

 va_start(args, format);
 /* log name of function causing error */
 (void) syslog(pri, "ERROR in %s.", function_name);
 /* log remainder of message */
 (void) vsyslog(pri, format, args);
 va_end(args);
 (void) abort( );
}

main()
{
 error(LOG_ERR, "main", "process %d is dying", getpid());
}

See attributes(5) for descriptions of the following attributes:

syslog(3C), attributes(5)