From mboxrd@z Thu Jan  1 00:00:00 1970
From: "rob pike" <rob@plan9.bell-labs.com>
To: 9fans@cse.psu.edu
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Message-Id: <20001109183459.1DEAA199F1@mail.cse.psu.edu>
Subject: [9fans] History
Date: Thu,  9 Nov 2000 13:34:57 -0500
Topicbox-Message-UUID: 266a111e-eac9-11e9-9e20-41e7f4b1d025

Now that you've recovered your breath from laughing uproariously at my
joke this morning - oh, was that politics you were laughing at?  sorry
- anyway, here's what I do for history.  I've sent them before but I
keep tweaking them and maybe it's time to send them again.  You need
to fix the pattern to match your prompt.  It's an exercise for the
reader to see how they work and how to use them.  Based on an idea
from rsc, I think.  I hardly ever use them when I have a mouse, but if
I'm stuck with a nipple-mouse I use them a lot.

-rob

% cat /bin/"
#!/bin/rc

rfork en

if(test -r /mnt/acme/acme/body)
	bind /mnt/acme/acme/body /dev/text

PROMPT='[^ 	]*%+[ 	]+'

fn cmds {
	grep '^'$PROMPT'[^"]' /dev/text | sed 's/^/	/'
}

switch($#*) {
case 0
	cmds | tail -1
case *
	cmds | grep '^	'$PROMPT^$"* | {echo; cat} |
		pr -t -n | sort -nr | sort -u +1 | sort -n |
		sed 's/^ *[0-9]+	//' | grep .
}

# the silly {echo; cat} gets around pr printing "empty file" when
# presented with no input.
% cat /bin/""
#!/bin/rc

rfork e

PROMPT='[^ 	]*%+[ 	]+'

_x = `{" $* | tail -1}
if(~ $#_x 0) {
	echo no such command found
	exit notfound
}

echo $_x
_x=`{ echo -n 'eval '; echo $_x | sed 's/^'$PROMPT'//'}
rc -c $"_x
%