From: utzoo!decvax!cca!fred.umcp-cs@Udel-Relay@sri-unix
Newsgroups: net.unix-wizards
Title: amusing hack in 4.1BSD C-shell
Article-I.D.: sri-unix.3316
Posted: Fri Sep 17 01:06:36 1982
Received: Fri Sep 17 06:29:53 1982

From:     Fred Blonder 
Date:     13 Sep 82 18:58:39-EDT (Mon)
The C-shell can be made to display your current working directory in your
shell prompt by the following commands:

	alias cd 'if ("\!:0-$" == cd) cd; if ("\!:0-$" != cd) cd \!$; \
				set prompt = "[$cwd] ==> "'
	alias pushd 'if ("\!:0-$" == pushd) pushd; if ("\!:0-$" != pushd) \
				pushd \!$; set prompt = "[$cwd] ==> "'
	alias popd 'if ("\!:0-$" == popd) popd; if ("\!:0-$" != popd) \
				popd \!$; set prompt = "[$cwd] ==> "'

Sick huh? Useful too. (sometimes)