Encode time, date and a number into a few alphanumeric characters

Question

I'd like to encode certain information, such as date and time of build and the SVN revision, into a reversible alphanumeric string so I can easily identify a build (besides maintaining a table of known builds).

I have no idea of how to go about this. Can you point me to related algorithms, commands, etc that will help me with this?

Answer 1

If you don’t need it to be too too short, use Base64 encoding.

$ echo $(date +%s)-r3749 | base64
MTM1ODg4MzA3MS1yMzc0OQo=
$ echo MTM1ODg4MzA3MS1yMzc0OQo= | base64 --decode
1358883071-r3749

Here I used an Epoch time since it’s fewer characters than a full date. Since it’s a number, and the SVN revision is a number too, you could also encode them using a different base. Using this Base 62 encoding function, you could reversibly encode the (date, revision) pair 1358883071-r3749 as 1tXJyT,Yt

But Base64 is probably short enough, and it’s super easy.