Overwrite logfile after move action

[Prem]

Hello, I have a task that moves files from location A to location B when a fodler contents changes. This one works, but:
Now I want an additional task that overwrites a textfile with the performed actions and results. Something like:
If task succesful, then:

Filename 111111.11 was moved from
[foldername location A]  to  [foldername location B]
Bytes moved: xxxxxx
Filename 222222.22 was moved from
[foldername location X]  to  [foldername location Y]
Bytes moved: xxxxxx
Etc....
If one of the files was unable to be moved, then in between the others in the listing, there should be:

Unable to move file XXXX.XX !
I am unable to use the normal logfile of Robotask, because that contains too much other information that I dont need to show in the text file.
Any help is very much appreciated.
Thanks
Prem