[K12OSN] OT: bash scripting - check for permissions, check for existence of file in directory tree

[Rob Owens]

Nils Breunese wrote:
> David Hopkins wrote:
> 
>> What about using the locate command (which is much faster) in a
>> script? And then testing if the command returned successfully, e.g.
>>
>> locate somefile
>> if [ $? -eq 0 ] then
>> # successfully located somefile
>> # operate on the file (or check that it is part of the correct
>> directory structure?)
>> fi
>>
>> $? returns the success/failure of the immediately preceding command.
>> and if run updatedb each night, locate will work for any but the most
>> recent files?
> 
> That works if the frequency at which your locate database is updated if
> good enough for your application. You could add an extra check to see if
> the file really exists after locate says it exists. You'll still miss
> files that were created after the last time your locate database was
> updated. If you want to have the most recent info about your filesystem
> you'll just have to stick with find.
> 
> I guess it also depends on whether the directory you're searching has a
> lot of files. If it's not too big it's probably not worth it to use
> locate and sacrifice precision.
> 
Thanks, that would probably be a good option for me too.  It would be a
rare case that we issue a drawing and then obsolete it in the same day
(and that's what this script is for -- obsoleting drawings).

This is what I've been using for the past couple of days in my testing:

if [ 'find $MASTERDIR -name $(basename $OLDREV)' ]; then
          stamp_and_move $OLDREV
else
          error-file_location
          exit
fi

-Rob
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