Batch script to conditionally delete files

Question

Owners of Nokia Lumia 1020 know it can be set to store captured photos at full resolution, but the reduced size photos are also stored. I would like to have a script to automatically delete all the low resolution versions.

The filenames are kind of the following:

WP_20150303_17_20_38_Pro.jpg
WP_20150303_17_20_38_Pro__highres.jpg
WP_20150303_17_21_21_Pro.jpg
WP_20150303_17_21_21_Pro__highres.jpg
WP_20150303_17_21_32_Pro.jpg
WP_20150303_17_21_32_Pro__highres.jpg
WP_20150303_17_22_47_Pro.jpg
WP_20150303_17_22_47_Pro__highres.jpg
WP_20150303_17_28_14_Pro.jpg
WP_20150303_17_28_14_Pro__highres.jpg

I could delete *_pro.jpg, but then there is a risk that what if there is no high resolution version at all. How can I write a script that would first check if there is a highres file present and only then delete lowresolution version?

Solution

Create a batch file. Start here: Loop command: against the results of another command and here: Command Line arguments (Parameters)

For /F "tokens=*" %%G in ('dir /b *_pro.jpg') do (
   echo %%~dpnG
)

Now you could change echo %%~dpnG to

   if exist "%%~dpnG__highres.jpg" echo del "%%~dpnxG"

or even to

   if exist "%%~dpnG__highres.jpg" (
        echo del "%%~dpnxG"
   ) else (
        echo retain %%~dpnxG
   )

Thoroughly check the output (better twice) and substitute echo del with del.

Add /s switch to dir command as follows: dir /b /s *_pro.jpg to treat files in subfolders as well.