KLOG(7)								       KLOG(7)

NAME    [Toc]    [Back]

     klog - kernel error logging interface

DESCRIPTION    [Toc]    [Back]

     Minor device 0 of the klog	driver is the interface	between	a process and
     the kernel's error	logging	mechanism.  When this device is	open, messages
     printed by	the kernel, which normally appear only in the system console
     window, also are buffered by the klog driver.  The	data obtained by
     reading from this driver are the text of the kernel messages.  The	driver
     may be opened only	for reading by a single	process.  Each read causes the
     requested number of bytes to be retrieved;	the request is truncated if
     the read request is for more than the data	currently available.

     Normally, this device is opened and read by syslogd(1M), the system
     logging daemon.

     This special device supports the following	open(2)	flags:

	  O_NDELAY
	       When set	a read will not	block if no data is present.  If not
	       set, a read will	block until information	becomes	available.

     Each ioctl(2) call	that this special device supports has the form:

	  ioctl(fd, cmd, arg)

     where the format and meaning of arg vary with the specified cmd as
     described below:

	  FIONREAD
	       Returns the number of bytes currently available to read to the
	       area pointed to by arg, where arg is treated as a pointer to a
	       variable	of type	size_t.

	  FIONBIO
	       Enables or disables non-blocking	mode, according	to the boolean
	       value supplied as arg.  Enabling	this mode has the same affect
	       as the O_NDELAY flag for	open(2).

	  FIOASYNC
	       Enables or disables asynchronous	mode, according	to the boolean
	       value supplied as arg.  When asynchronous mode is enabled, the
	       process group associated	with the open of the special device
	       receives	a SIGIO	signal when data is available to be read.

	  TIOCSPGRP
	       Set the process group for use with asynchronous I/O (FIOASYNC).
	       For this	command, arg should contain the	process	group id.

	  TIOCGPGRP
	       Returns the current process group to the	area pointed to	by
	       arg, where arg is treated as a pointer to a variable of type



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KLOG(7)								       KLOG(7)



	       int.

FILES    [Toc]    [Back]

     /dev/klog special file

SEE ALSO    [Toc]    [Back]

     open(2), ioctl(2),	syslogd(1M)


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