Step 3

Step 3: Using filters

Why to use filters

Filters allow to exclude files from the scan. This has two main purposes: Firstly, reducing the amount of files by limiting it to the ones that currently interest you speeds up the scan and secondly you can use filters to protect certain files from being scanned and possibly appearing in the result list.

Using file masks

If you are only interested in files of a certain type (more general: files following a certain naming scheme), you can use file masks to limit the scan to these files only. You can also exclude certain files from the scan to protect them.
The masks can be set up in the middle of the Scan Options page where you can find two lists of file masks. You can add masks to the lists by entering them below and pressing return. The upper mask list limits the scan to certain files while the second one excludes files from the scan.
In our example we will limit the scan to MP3 files and leave the exclusion list as it is, protecting the most common system files from being scanned (note: this is just a basic protection, DoubleKiller cannot recognize all files that are needed by Windows or some other software!). To do so, add '*.mp3' to the upper list.

To learn the meaning of '*.mp3' and what file masks are at all, please refer to File names. For more advanced usages of file masks see Syntax of file masks.

Filtering by file size

At the bottom right of the Scan Options page you can define a file size range the scan is to be limited to or that is to be excluded from the scan. This is quite easy: Use the three radio buttons to choose the filter mode and enter the minimal and maximal range values below.
In our example we will limit the scan to files between 500 kB and 12 MB to exclude both very small files and big ones - as we are scanning for MP3 files, we will probably only have duplicates in the range of 3-5 MB anyway. There are MP3 files smaller than 500 kB in our Sounds directory 'F:\Sounds', but they are free from duplicates and do not need to be scanned.