1BSD/ex-1.1/SETUP

October 12, 1977

The editor uses the following data bases:

	/etc/ttytype		gives teletype types of hardwire ports
	/etc/ttycap		gives capabilities of teletypes
	/etc/htmp		gives home directories and teletype types

The implications of the absence of these are as follows:

	/etc/ttycap
		Editor will think all terminals are model 33 teletypes,
		essentially, as they will be "unknown."  You'll have
		no way of specifying the capabilities of your terminal.

	/etc/ttytype
		You will have to tell the editor the type of the terminal
		you are on every time you log in, unless you trust
		that the way the last user of your port set your terminal
		type is correct.

	/etc/htmp
		Editor start-up files cannot work;  you won't be able to
		specify your terminal type once per login... you have to
		do it each time you enter the editor.

These data bases are maintained and used in the following ways:

	HTMP data base:
		The file /etc/htmp contains a structure described by htmp (V).
		It contains, for each user, his "home" directory, normally
		the login directory, his user-id, and the type of terminal
		he is on.  The home directory is here because on large
		systems searching the password file is unreasonably slow.
		Its presence in this data base also allows it to be changed.
		The tty type information is necessary here because users
		who dial in on a dialup port need to be able to specify it.

	TTYTYPE data base:
		The file /etc/ttytype is organized similarly to /etc/ttys
		and maps tty names to 2 character codes.  This data base is
		used both by the editor and by the program "tset", and
		can be used by other programs.

	TTYCAP data base:
		The file /etc/ttycap allows programs to map a terminal's
		type code to its characteristics.  This allows addition
		of new terminals to the system without changing any existing
		programs - only the data base needs to be updated.  (Note
		that currently cursor addressing information is not recorded
		here requiring changes to the editor to add new such terminals.)

The following utility programs are included with the editor:

	SETHOME
		Set the home directory entry in /etc/htmp.

	TTYTYPE
		Set the teletype type entry in /etc/htmp.

The following changes to support the editor are suggested:

	LOGIN
		So that naive users may login on dial up ports and have
		their home directory and terminal-type set to reasonable
		values at initialization without any action on their part,
		the program login should be changed to write the initial
		entry in /etc/htmp.  The work involved is in getting the
		terminal type from the file /etc/ttytype and writing it
		into /etc/htmp.  The overhead should be negligible,
		especially since the operations of reading /etc/passwd
		and looking for mail in /usr/mail are typically much more
		expensive.  This change is simple to make, just calling
		some of the routines in the supplied library htmp (V) ..

	SU
		So that the home directory will be correct after a su
		command, the command should be changed to save and restore
		this entry in /etc/htmp before and after the su.
		This is similar to the saving and restoring of the utmp
		user byte entry to allow who to print out the name of
		the person one is su'd to.  (This latter change has been made
		at Berkeley.)

For more information on formats and programs see the following documents

	Section V:	htmp, ttycap, ttytype
	Section VI:	sethome, ttytype
	Section VII:	htmp, typeof, ttycap


					Bill Joy
					CS Division
					Department of EE and CS
					UC Berkeley
					Berkeley, California 94704

					(415) 524-4510		[home]
					(415) 642-4948		[school]