Dear Nye Liu /usr/lib/os-release does have enough informations to read the current suite name of the installed system.
PRETTY_NAME="Debian GNU/Linux 10 (buster)" NAME="Debian GNU/Linux" VERSION_ID="10" VERSION="10 (buster)" VERSION_CODENAME=buster ID=debian HOME_URL="https://www.debian.org/"; SUPPORT_URL="https://www.debian.org/support"; BUG_REPORT_URL="https://bugs.debian.org/"; and running a single command like "apt search base-files" will give you the information if it is oldstable, stable, testing or something else. Example: apt search base-files Sortierung... Fertig Volltextsuche... Fertig base-files/oldstable,now 10.3+deb10u10 amd64 [installiert] Debian base system miscellaneous files oldstable is in the line base-files/oldstable. If you combine both, you will know the stable/testing to suite name mapping of the current installed system. I hope this helps. Best Regards Oliver
