Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!mcnc!rti!trt
From: trt@rti.rti.org (Thomas Truscott)
Newsgroups: comp.misc
Subject: Re: Your favourite UNIX-pipe (summary)
Summary: && is often better than ;
Message-ID: <4002@rtifs1.UUCP>
Date: 3 Aug 90 20:55:15 GMT
References: <730@coma.UUCP> <2987@awdprime.UUCP> <2400@dino.cs.iastate.edu>
Organization: Research Triangle Institute, RTP, NC
Lines: 18

>     Here's a good one (stolen from an Ultix man page):
>          (cd fromdir; tar cf - .) | (cd todir; tar xpf -)

I have learned that

          (cd fromdir && tar cf - .) | (cd todir && tar xpf -)

is a safer form of this command.  Guess how I learned :-)
In general, use "a && b" rather than "a ; b"
if you only want to do "b" if "a" succeeds.

Some versions of /etc/rc have a line to delete trash from /tmp:
	(cd /tmp; rm -f *)		# Not recommended
I wonder what happens if /tmp is inadvertently missing, or mode 0?
I guess it just deletes trash in some other directory :-)
	(rm -f /tmp/*)			# Recommended
seems wiser, particularly since files in /tmp can be named "-r" or "-i".
    Tom Truscott