The quick way is to run “lsb_release -a”
$ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 9.10 Release: 9.10 Codename: karmic
Or just read the info from /etc/lsb-release
$ cat /etc/lsb-release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=9.10 DISTRIB_CODENAME=karmic DISTRIB_DESCRIPTION="Ubuntu 9.10"
It is also possible to check the file “/etc/issue”
$ cat /etc/issue Ubuntu 9.10 \n \l
From X check out System->about.