Getting a unique id from a unix-like system

Question

I want to get from any Unix-like system (if this is possible) a unique id that will be persistent every time my application runs in the same machine. If it is possible, I wa

Answer 1

The answers from Jason Day and A.Danischewski seem to be on the right track but don't meet your criteria of any "Unix-like system" since /sbin/blkid and /etc/fstab don't exist on OSX.

The only 100% portable approach would be to choose a standard location for a file that your own application will create, e.g. /etc/YOURAPP.cfg and store a UUID there if one doesn't already exist.

Far from ideal, since another person or application could delete the file or change it, or if the user changed out the root file system you could lose the ID from the current machine, or it could come into being on another machine. Not to mention issues with read and write permissions and so on.

But in the end there is no such thing as "the same machine". Any computer is no more and no less than its components + current configuration. I don't think you can do any better than this, portably.