I currently have a batch job that performs many functions. Two of them are below. I was wondering how this can be done in a custom class

mv $TEMPDIR/$FILE $TEMPDIR/$FILEa"_$DATESTAMP.txt"
mv $TEMPDIR/$FILE1 $TEMPDIR/$FILE1a"_$DATESTAMP.txt"
mv $TEMPDIR/$FILE2 $TEMPDIR/$FILE2a"_$DATESTAMP.txt"
mv $TEMPDIR/$FILE3 $TEMPDIR/$FILE3a"_$DATESTAMP.txt"
mv $TEMPDIR/$FILE4 $TEMPDIR/$FILE4a"_$DATESTAMP.txt"
#Gzip files
find $TEMPDIR -type f ! -iname '*gz' -exec gzip '{}' \;

Thank you