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Path: utzoo!mnetor!uunet!mcvax!ukc!its63b!simon
From: simon@its63b.ed.ac.uk (Simon Brown)
Newsgroups: comp.bugs.sys5
Subject: Re: sh bug
Message-ID: <706@its63b.ed.ac.uk>
Date: Thu, 29-Oct-87 05:41:16 EST
Article-I.D.: its63b.706
Posted: Thu Oct 29 05:41:16 1987
Date-Received: Wed, 4-Nov-87 04:44:41 EST
References: <467@virginia.acc.virginia.edu>
Reply-To: simon@its63b.ed.ac.uk (Simon Brown)
Organization: Computer Science Department, Edinburgh University
Lines: 33

In article <467@virginia.acc.virginia.edu> mer6g@virginia.UUCP (Marc Rouleau) writes:
>On our 3b2, 3b5, and 3b15 AT&T systems running SYSV.2 and SYSV.3, sh does
>something rather unfortunate when certain built-in functions fail.  For
>example,
>
>	cd nowhere || echo 'cd failure'
>
>where ``nowhere'' is nonexistent does not (as you might expect) cause ``cd
>failure'' to be echoed to the screen.  The expected error message is produced
>and then . . . nothing, a new prompt.
>

Dat's 'cos the first cd fails, so the shell interrupts itself (well, sort of),
and jumps straight back to command level - without executing the second part of
the "||". What you'll have to do is force the first component to be executed
in a subshell so it can't effect the second - like
	if (cd nowhere)		# cd in a subshell
	then cd nowhere		#  it worked, so cd in the main shell
	else echo 'cd failure'  #  otherwise print error message
  	fi
Of course, you still get the error message from the first cd (if it fails),
unless you redirect it's output elsewhere with
	if (cd nowhere) >/dev/null 2>&1

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