Short Tip: Renaming log files to include date...

I had a bunch of a log files in the format logfilename.N.gz, but I wanted to rename them into logfilename.YYYYMMDD.gz where YYYYMMDD is a date when the file was last modified. I did it using the following for loop:

for i in logfilename.*.gz
do
    mv -i $i logfilename.`date -r $i +%Y%m%d`.gz
done

The argument -r to date(1) command tells it to use the last modification date (mtime) of a file given as the argument to the option. Note that it is also possible to use stat(1) command instead of date(1).