SYSLOG(3C)							    SYSLOG(3C)

NAME    [Toc]    [Back]

     syslog, openlog, closelog,	setlogmask, vsyslog - control system log

SYNOPSIS    [Toc]    [Back]

     #include <syslog.h>

     void openlog(const	char *ident, int logopt, int facility);

     void syslog(int priority, const char *message, parameters...);

     void closelog(void);

     int setlogmask(int	maskpri);

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

DESCRIPTION    [Toc]    [Back]

     Syslog arranges to	write message onto the system log maintained by
     syslogd(1M).  The message is tagged with priority.	 The message looks
     like a printf(3S) string except that %m is	replaced by the	current	error
     message (collected	from errno).  A	trailing newline is added if needed.
     This message will be read by syslogd(1M) and written to the system
     console, log files, or forwarded to syslogd on another host as
     appropriate.  Vsyslog is like syslog except that instead of being called
     with a variable number of arguments, it is	called with an argument	list
     as	defined	by stdarg(5).

     Priorities	are encoded as a facility and a	level.	The facility describes
     the part of the system generating the message.  The level is selected
     from an ordered list:

     LOG_EMERG	   A panic condition.  This is normally	broadcast to all
		   users.

     LOG_ALERT	   A condition that should be corrected	immediately, such as a
		   corrupted system database.

     LOG_CRIT	   Critical conditions,	e.g., hard device errors.

     LOG_ERR	   Errors.

     LOG_WARNING   Warning messages.

     LOG_NOTICE	   Conditions that are not error conditions, but should
		   possibly be handled specially.

     LOG_INFO	   Informational messages.

     LOG_DEBUG	   Messages that contain information normally of use only when
		   debugging a program.





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SYSLOG(3C)							    SYSLOG(3C)



     If	syslog cannot pass the message to syslogd, it will attempt to write
     the message on /dev/console if the	LOG_CONS option	is set (see below).

     If	special	processing is needed, openlog can be called to initialize the
     log file.	The parameter ident is a string	that is	prepended to every
     message.  Logopt is a bit field indicating	logging	options.

     Current values for	logopt are:

     LOG_PID	   log the process id with each	message:  useful for
		   identifying instantiations of daemons.

     LOG_CONS	   Force writing messages to the console if unable to send it
		   to syslogd. This option is safe to use in daemon processes
		   that	have no	controlling terminal since syslog will fork
		   before opening the console.

     LOG_ODELAY	   Delay opening the connection	to syslogd until the first
		   syslog call.	This is	the default.

     LOG_NDELAY	   Open	the connection to syslogd immediately.	Useful for
		   programs that need to manage	the order in which file
		   descriptors are allocated.

     LOG_NOWAIT	   Don't wait for children forked to log messages on the
		   console.  This option should	be used	by processes that
		   enable notification of child	termination via	SIGCHLD, as
		   syslog may otherwise	block waiting for a child whose	exit
		   status has already been collected.

     LOG_PERROR	   Write messages to stderr as well as to syslogd.

     The facility parameter encodes a default facility to be assigned to all
     messages that do not have an explicit facility encoded:

     LOG_KERN	   Messages generated by the kernel.  These cannot be
		   generated by	any user processes.

     LOG_USER	   Messages generated by random	user processes.	 This is the
		   default facility identifier if none is specified.

     LOG_MAIL	   The mail system.

     LOG_DAEMON	   System daemons, such	as routed(1M), ftpd(1M), rshd(1M),
		   etc.

     LOG_AUTH	   The authorization system:  login(1),	su(1M),	getty(1M),
		   etc.	 ftpd(1M), and rshd(1M)	also use LOG_AUTH.

     LOG_LPR	   The line printer spooling system:  lpr(1), lpd(1M), etc.





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SYSLOG(3C)							    SYSLOG(3C)



     LOG_NEWS	   The network news system.

     LOG_UUCP	   The UNIX-to-UNIX Copy system:  uucp(1C), uucico(1M),
		   uux(1C), etc.

     LOG_LOCAL0	   Reserved for	local use.  Similarly for LOG_LOCAL1 through
		   LOG_LOCAL7.

     Closelog can be used to close the log file.

     Setlogmask	sets the log priority mask to maskpri and returns the previous
     mask.  Calls to syslog with a priority not	set in maskpri are rejected.
     The mask for an individual	priority pri is	calculated by the macro
     LOG_MASK(pri); the	mask for all priorities	up to and including toppri is
     given by the macro	LOG_UPTO(toppri).  The default allows all priorities
     to	be logged.

CAVEATS    [Toc]    [Back]

     A call to openlog does not	make a copy of the ident parameter, it merely
     stores a pointer to it.  This means that the caller cannot	re-use the
     memory in which the string	is stored.

EXAMPLES    [Toc]    [Back]

     syslog(LOG_ALERT, "who: internal error 23");

     openlog("ftpd", LOG_PID, LOG_DAEMON);
     setlogmask(LOG_UPTO(LOG_ERR));
     syslog(LOG_INFO, "Connection from host %d", CallingHost);

     syslog(LOG_INFO|LOG_LOCAL2, "foobar error:	%m");

SEE ALSO    [Toc]    [Back]

     syslogd(1M)


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