Lazy evaluation of exec clause in ssh Match statement

Iain Morgan imorgan at nas.nasa.gov
Thu Oct 31 08:09:58 EST 2013


On Wed, Oct 30, 2013 at 12:02:03 -0700, Iain Morgan wrote:
> Hello,
> 
> At present, if a ssh Match block contains an exec clause, the specified
> command is executed regardless of whether any preceding clauses are
> true. Thus,
> 
> 	Match host !*.* exec "some_command %h"
> 		...
> 
> would always execute some_command regardless of whether the host matches
> the preceding pattern. That seems undesirable, particularly as the
> user-specified command may do name lookups or other operations that may
> introduce delays.
> 
> Using a lazy approach, where the command is only executed if the
> preceding clauses are true would seem to be better.
> 
> -- 
> Iain Morgan
> _______________________________________________
> openssh-unix-dev mailing list
> openssh-unix-dev at mindrot.org
> https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev

It looks like there is alos an issue with negation, so a better example
of the initial issue would be:

 	Match user someuser exec "some_command %h"
 		...

-- 
Iain Morgan


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