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Re: Using && in commands
From: |
Paul D. Smith |
Subject: |
Re: Using && in commands |
Date: |
Thu, 6 Nov 2003 18:01:31 -0500 |
%% Robert Mecklenburg <address@hidden> writes:
rm> I have often used the shell && operator in commands run from make:
rm> foo:
rm> sed ... > /tmp/x && mv /tmp/x y
rm> but I am now questioning the value of this. Obviously, the above
rm> mv is executed only if sed returns success so it "protects" y from
rm> accidental clobbering. However, isn't that exactly what this
rm> does:
rm> foo:
rm> sed ... > /tmp/x
rm> mv /tmp/x y
rm> Assuming the -i flag isn't used (or .SILENT: etc.), is one form
rm> preferred over the other? Right now I prefer the second form.
In the case you give above they are equivalent. In fact I don't use &&
there. But in cases like this they are not equivalent:
foo:
cd foo && $(MAKE)
Or even something like:
foo:
for x in $(LISTOFSTUFF); do \
something && somethingelse ; \
done
In other words, I use "&&" when I need everything to run in the same
shell script, and multiple lines where it doesn't.
--
-------------------------------------------------------------------------------
Paul D. Smith <address@hidden> Find some GNU make tips at:
http://www.gnu.org http://make.paulandlesley.org
"Please remain calm...I may be mad, but I am a professional." --Mad Scientist