On 07/05/2012 09:16 AM, Akim Demaille wrote: > > Le 5 juil. 2012 à 16:53, Jim Meyering a écrit : > >> This script doesn't use set -e. >> I'd say that having to limit such use of "&&" is a good reason >> not to use "set -e". > > In my experience, not setting set -e is asking for troubles. > I have been bitten way too often because of failures that go > unnoticed, and the script just continues.
In my experience, 'set -e' is worthless in any shell scripting mixed
with functions. Test yourself - what does this output?
set -e
start() {
false
echo started successfully
}
start || echo >&2 failed
Believe it or not, POSIX requires it to output 'started successfully'
(why? see http://austingroupbugs.net/view.php?id=52). Furthermore, not
all /bin/sh obey POSIX, so you aren't even guaranteed that behavior
across platforms.
'set -e' can be useful in a strictly-controlled style of shell coding,
but the POSIX rules on how it behaves are quite non-intuitive and cause
more confusion than bugs that it would otherwise prevent by early exit
on error; and my opinion is that while all errors should be detected,
using 'set -e' as the crutch for the detection mechanism is bound to
cause careless programming that is harder to fix than coding correctly
in the first place.
--
Eric Blake ebl...@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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