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From: bink@aplcen.apl.jhu.edu (Ubben Greg)
Newsgroups: comp.unix.questions
Subject: Re: SYSV version of \"grabchars.c\".
Summary: Use head instead
Keywords: shell script GNU head stty
Message-ID: <1201@aplcen.apl.jhu.edu>
Date: 6 May 89 06:30:28 GMT
References: <19462@adm.BRL.MIL>
Reply-To: bink@aplcen.apl.jhu.edu (Greg Ubben)
Organization: The Johns Hopkins University, Baltimore MD
Lines: 28

In article <19462@adm.BRL.MIL> mark@ria-emh2.army.mil (Mark D. McKamey) writes:
>     I have recently recieved a copy of Mr. Dan Smith's "grabchars" program
> which allows you to get one or more keystrokes from the user, without
> requiring them to hit RETURN within a shell script.  The problem I have is
> that the program was written for BSD UNIX.  Has anyone ported said program
> to SYSV UNIX?  If so, would you please send me the SYSV patches.  Thank You.

    I wrote a System V script to allow single-keystroke input too, and came
up with a more general solution (not requiring the "grabchars" program).
I first used the stty command to allow reading single character responses.
Something like "stty -icanon min '^a'" but I don't have AFSVM handy, so
this is probably wrong.  Be sure to use stty -g to save the current modes
in a variable first, and set up a trap to restore them.  Then the only way I
found to actually read one character without a newline was to use a "head"
program I wrote (before I gnu about knew).  The code looked something like:

	case `head -1c` in
	[Yy])
		...
	[Nn])
		...

I would expect that GNU head could be used the same way.  Multi-sequence
keys would fool it (such as function keys) -- does grabchars handle this?
Is there a better way yet (in shell)?

					-- Greg Ubben
					   bink@aplcen.apl.jhu.edu