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Date: Tue, 17 Dec 1991 02:15:24 -0600
From: "Paul D. Swasey" <ps3u+@andrew.cmu.edu>
To: rc@archone.tamu.edu
Subject: 'cd -'

Here is a simple way to get the effect of kshes 'cd -', it costs an
extra line per cd command in your $history but it only costs one
variable (the current directory cache) and one call to "pwd", when
leaving the current directory (if the current directory is not $home).

(it's nice for me because I do "pwd" a lot, anyway, so "cd" only has
to calculate the current directory about half the time...)

sample:
peso ; pwd
/afs/andrew.cmu.edu/system/src/contributed/niftylibs/017/util
peso ; cd
peso ; - cd
cd /afs/andrew.cmu.edu/system/src/contributed/niftylibs/017/util
peso ; tail -7 $history
pwd
cd
cd /afs/andrew.cmu.edu/system/src/contributed/niftylibs/017/util
- cd
cd /afs/andrew.cmu.edu/system/src/contributed/niftylibs/017/util
cd /afs/andrew.cmu.edu/usr16/ps3u
tail -7 $history
peso ;

er, make that 2 extra lines per cd command (i forgot about the one
added by -(1) )

-dave
-----
fn cd {
        builtin cd $1 && {
		if (!~ $history ())
			echo cd `pwd >>$history
		switch ($1) {
		case ()
			PWD=$home
		case *
			PWD=()
		}
	}
}
fn pwd {
        if (~ $PWD ())
		PWD=`{builtin pwd}
        echo $PWD
}