Deleting a custom list of files

Consider a scenario where you have to delete some files but you don't have the names of the files to delete beforehand. If you can specify that list with regular expressions, it wouldn't be a problem, but sometimes that is not possible. In such cases you should use a helper transformation that builds the list of files to delete. This recipe shows you how to do that.

For this recipe, assume that you want to delete from a source directory all the temporary files that meet two conditions: the files have a .tmp extension and a size of 0 bytes.

Getting ready

In order to create and test this recipe, you need a directory with a set of sample files; some of them should have the .tmp extension and zero size. Some example files are shown in the following screenshot:

In the preceding screenshot, the files that must be deleted are sample3.tmp, sample5.tmp, and sample7.tmp because they match the requirements of having .tmp as their file type and they do not contain anything...