Re: weird behavior of set -e

[Eric Blake]

On 06/24/2011 03:51 AM, Harald Dunkel wrote:
> Hi folks,
> 
> A colleague pointed me to this problem: If I run
> 
>       ( set -e; ( false; echo x ) )
> 
> in bash 4.1.5, then there is no screen output, as
> expected. If I change this to
> 
>       ( set -e; ( false; echo x ) || echo y )
> 
> then I get "x" instead of "y". How comes?

Because '(false; echo x)' is on the left hand of ||, which disables set
-e for that portion of the command line.  ksh behaves the same way, so
it is not a bash bug.

> Any helpful comment would be highly appreciated.

set -e seldom does exactly what you want - even the writers of POSIX
2008 got it wrong, and here's how they corrected it:

http://austingroupbugs.net/view.php?id=52

and that's what bash 4.1 implemented.

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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