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From: duk@ace.UUCP (Duk Bekema)
Newsgroups: comp.unix.questions
Subject: System V.2 Bourne shell question
Message-ID: <446@ace.UUCP>
Date: Fri, 16-Oct-87 04:44:04 EDT
Article-I.D.: ace.446
Posted: Fri Oct 16 04:44:04 1987
Date-Received: Sun, 18-Oct-87 09:27:11 EDT
Sender: news@ace.UUCP
Organization: ACE Associated Computer Experts bv, Amsterdam
Lines: 37
Keywords: backslash


I have some questions about the V.2 Bourne shell.
The following line:
	echo /other/duk | sed -e 's/\//\\/g'
prints
	\other\duk
So far, so good.
Now I want to assign this to a shell variable, so I try
	msdos=`echo /other/duk | sed -e 's/\//\\/g'`
This prints
	sed: command garbled: s/\//\/g
	                        ^
				note the backslash
Why doesn't it print
	sed: command garbled: s///\/g
Since an extra shell is invoked for evaluating the command
between backquotes, I thought every backslash had to be doubled,
since the additional shell strips of the single quotes.
However, the commands
	msdos=`echo /other/duk | sed -e 's/\//\\\/g'`
	echo $msdos
and
	msdos=`echo /other/duk | sed -e 's/\\//\\\\/g'`
	echo $msdos
both produce
	\other\duk
If I set the -x flag, I see that in both cases the command
	s/\//\\/g
is passed to sed.

Can anyone explain this to me? Is there someone who can try this
on a V7 or 4.xBSD Bourne shell?
Please mail responses to me, I'll post a summary to the net.
-- 

Duk Bekema
...!{seismo|decvax|philabs}!mcvax!ace!duk