Invoking rsync from a script with null parameters
Kevin Korb
kmk at sanitarium.net
Sun Nov 4 20:35:04 MST 2012
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I suspect you are missing a space somewhere and are ending up with 2
parameters stuck together. You can have bash output the rsync command
line it intends to run to make sure or you can just use " " instead of
"" as extra spaces between parameters will have no effect.
On 11/04/12 22:23, Joe wrote:
> I'm working on a bash backup script using rsync. (kubuntu precise
> 12.04, rsync 3.0.9-1ubuntu1)
>
> To avoid having a number of slightly different rsync commands, I
> would like to use shell variables as part of the rsync command.
> I.e.: DRYRUN="-n" rsync "${DRYRUN}" more parameters ...
>
> This does not work if DRYRUN="" - apparently because this command
> becomes rsync "" more parameters ... instead of rsync more
> parameters ...
>
> and rsync uses the null parameter for something and does not
> perform as expected. It does not generate any error or diagnostic
> message.
>
> Is there a way to get around this problem - other than coding each
> permutation of the command separately?
>
> I'm experimenting with putting the whole rsync command in a string
> so I can run it after any null parameters revert to pure white
> space. Once I get the quoting to work (preserving those quotes I
> still need), this method should work, but it's less than elegant.
>
> Is this a bug in rsync? (Shouldn't it at least complain/error exit
> if it gets something like this that it doesn't understand?) If it
> is, what's the best way to report it?
>
> Ideally (for me anyway), I would like it to completely ignore any
> null parameters, but I don't know what problems that might cause
> for other people.
>
> TIA
>
> Joe
>
- --
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Kevin Korb Phone: (407) 252-6853
Systems Administrator Internet:
FutureQuest, Inc. Kevin at FutureQuest.net (work)
Orlando, Florida kmk at sanitarium.net (personal)
Web page: http://www.sanitarium.net/
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