Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!amdahl!pacbell!pbhyf!rob
From: rob@PacBell.COM (Rob Bernardo)
Newsgroups: comp.unix.questions
Subject: Re: UNIX prompts (-ksh)
Message-ID: <4896@pbhyf.PacBell.COM>
Date: 27 Mar 89 13:52:38 GMT
References: <18805@adm.BRL.MIL> <11080@well.UUCP> <2391@buengc.BU.EDU> <4549@vpk4.UUCP>
Reply-To: rob@PacBell.COM (Rob Bernardo)
Organization: Pacific * Bell, San Ramon, CA
Lines: 33

In article <4549@vpk4.UUCP> hjespers@attcan.UUCP (Hans Jespersen) writes:
+In article <2391@buengc.BU.EDU> bph@buengc.bu.edu (Blair P. Houghton) writes:
+>In article <11080@well.UUCP> tneff@well.UUCP (Tom Neff) writes:
+>>Actually not even the classic Korn shell solution of
+>>
+>>	export PS1='$PWD> '
+>>
+>>seems to work everywhere.  
+ 
+>I don't know ksh, but all the other shells I've seen use single-quotes
+>to protect against variable substitution...
+
+Absolutely correct. I think Tom ment
+
+	export PS1=`$PWD> `
+                   ^      ^

Absolutely wrong. :-) The above will set PS1 to be your current working
directory ***at the time it was set***. It will not change from command
to command no matter how much you "cd". On the other hand, the following:

	export PS1='$PWD> '
    
will set PS1 to literally be "$PWD> ". Then, you ask, wouldn't the prompt
come out as literally "$PWD> ". The answer is no. The two environmental
variables ENV and PS1 undergo variable substitution by ksh *when used*.
This is why you can put $PWD in PS1 and have it reflect your cwd as it
changes with each command.
-- 
Rob Bernardo, Pacific Bell UNIX/C Reusable Code Library
Email:     ...![backbone]!pacbell!pbhyf!rob   OR  rob@pbhyf.PacBell.COM
Office:    (415) 823-2417  Room 4E850O San Ramon Valley Administrative Center
Residence: (415) 827-4301  R Bar JB, Concord, California