Path: utzoo!attcan!uunet!vsedev!logan
From: logan@vsedev.VSE.COM (James Logan III)
Newsgroups: comp.unix.wizards
Subject: Re: Shell script help needed
Keywords: Suspend a foreach() loop?
Message-ID: <1248@vsedev.VSE.COM>
Date: 22 Nov 88 23:47:10 GMT
References: <1872@loral.UUCP>
Reply-To: logan@vsedev.VSE.COM (James Logan III)
Organization: VSE Software Development Lab
Lines: 66

In article <1872@loral.UUCP> jlh@loral.UUCP (Physically Pffft) writes:
>Our application has it's source code in 9 directories, and I find that
>often I need to make similar changes in all 9 directories.  Manually
>cd'ing into each directory is error prone, some are skipped and others
>are entered more than once.  I'd like to write a shell script to automate
>this that would act as follows:
>
>1.  Enter all the directory names into a file (only need to do once)
>2.  Invoke the script, it reads the first directory from the file and
>    cd's into it.  It then suspends itself.
>3.  I do what I need to.
>4.  I enter 'next' or something to wake up the script, it reads the next
>    directory from the file and cd's into it.  Steps 2-4 are done for
>    all directories.
>
>My problem is I don't know how to suspend a shell script like this, and then
>have it continue where it left off.  My only idea is to create a new shell
>('/bin/sh'), but I think this would be slower than snail snot.  Anyone
>have any ideas?  Thanks.

Invoking another instance of /bin/sh should not be slow since the
text segment of /bin/sh is shared by more than one process.  

I wrote you the following shell script that runs VERY quickly on
my system.  It will handle the requirements you posted.  Just type
"^D" (control-D) or "exit" to go to the next directory.

			-Jim

------------ CUT HERE --------------
#	autocd.sh	James Logan	Tue Nov 22 18:27:16 EST 1988
#		Read a list of directories from $DIRFILE and invoke
#		an interactive shell for each directory.

#
# Set DIRFILE if not already set to something else in the
# user's environment.
#
DIRFILE=${DIRFILE:-"dirs"};

if test ! -r "$DIRFILE"; then
	echo >&2 "$0: Cannot read '$DIRFILE'.";
	exit 1;
fi;

#
# Feed the file $DIRFILE into stdin and read a line at a time.
#
while read DIR; do
	echo "\nChanging to directory '$DIR'";
	if cd $DIR; then
		PS1="$DIR> ";
		export PS1;

		# Redirect stdin from user's tty -- it is currently
		# connected to $DIRFILE (inherited from the while loop).
		sh -i </dev/tty;
	fi;
done <$DIRFILE;

echo "\07\nDone.\07";
-------------- CUT HERE ------------------
-- 
Jim Logan		logan@vsedev.vse.com
(703) 892-0002		uucp:	..!uunet!vsedev!logan
			inet:	logan%vsedev.vse.com@uunet.uu.net