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ttysrch(4)			 File Formats			    ttysrch(4)

       ttysrch - directory search list for ttyname

       ttysrch	is  an	optional file that is used by the ttyname library rou-
       tine. This file contains	the names of directories in /dev that  contain
       terminal	and terminal-related device files. The purpose of this file is
       to improve the performance of ttyname by	indicating  which  subdirecto-
       ries  in	 /dev  contain	terminal-related  device  files	 and should be
       searched	first. These subdirectory names	must appear on separate	 lines
       and  must begin with /dev. Those	path names that	do not begin with /dev
       will be ignored and a warning will be sent to the console. Blank	 lines
       (lines  containing  only	white space) and lines beginning with the com-
       ment character "#" will be ignored. For each file  listed  (except  for
       the special entry /dev),	ttyname	will recursively search	through	subdi-
       rectories looking for a match. If /dev appears in the ttysrch file, the
       /dev  directory	itself will be searched	but there will not be a	recur-
       sive search through its subdirectories.

       When ttyname searches through the device	files, it tries	to find	a file
       whose major/minor device	number,	file system identifier,	and inode num-
       ber match that of the file descriptor it	was given as an	argument. If a
       match  is not found, it will settle for a match of just major/minor de-
       vice and	file system identifier,	if one can be found. However,  if  the
       file descriptor is associated with a cloned device, this	algorithm does
       not work	efficiently because the	inode number  of the device file asso-
       ciated  with a clonable device will never match the inode number	of the
       file descriptor that was	returned by the	open of	that clonable  device.
       To help with these situations, entries can be put into the /etc/ttysrch
       file to improve performance when	cloned devices are used	 as  terminals
       on a system (for	example, for remote login). However, this is only use-
       ful if the minor	devices	related	to a cloned device are put into	a sub-
       directory.  (It	is  important to note that device files	need not exist
       for cloned devices and if that is the  case,  ttyname  will  eventually
       fail.) An optional second field is used in the /etc/ttysrch file	to in-
       dicate the matching criteria. This field	is separated  by  white	 space
       (any combination	of blanks or tabs). The	letter M means major/minor de-
       vice number, F means file system	identifier, and	I means	inode  number.
       If  this	 field is not specified	for an entry, the default is MFI which
       means try to match on all three.	For cloned devices the field should be
       MF, which indicates that	it is not necessary to match on	the inode num-

       Without the /etc/ttysrch	file, ttyname will search the  /dev  directory
       by  first  looking in the directories /dev/term,	/dev/pts, and /dev/xt.
       If a system has terminal	devices	installed in  directories  other  than
       these,  it may help performance if the ttysrch file is created and con-
       tains that list of directories.

       Example 1: A sample display of /etc/ttysrch command.

       A sample	/etc/ttysrch file follows:

       /dev/term     MFI
       /dev/pts	     MFI
       /dev/xt	     MFI
       /dev/slan     MF

       This file tells	ttyname	that it	should first search through those  di-
       rectories  listed  and that when	searching through the /dev/slan	direc-
       tory, if	a file is encountered whose major/minor	devices	and file  sys-
       tem  identifier	match that of the file descriptor argument to ttyname,
       this device name	should be considered a match.



SunOS 5.10			  23 Feb 1994			    ttysrch(4)


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