I use this handy command so often that I’d forgotten to make a note of it here for everyone.

If you want to make a copy of a file with the same filename and a predetermined suffix of your choice then run this command replaceing the YYYYMMDD date with anything you want:

cp haproxy.cfg{,.20170209}

The above command copies haproxy.cfg into a file called haproxy.cfg.20170209
Anything after the comma can be changed as you wish.