I need to abstract data from a text file, but if the file extension is
".log", I need to change it to ".txt".

I can only think of doing this by first opening "ABC.log" (in the
background), upon detection of a .log extension, will use "Save As.. ABC.txt

this was what I did manually at first, but I need to speed up as there are
going to be tens of files with .log extension to be converted..

can anyone help?