/etc/locale.gen
Whitespace-separated newline-delimited locale charset list of locales to build with # start-of-line comments.
Generate localisation files from templates
locale-gen [--keep-existing]
As compiled locales are large, only templates are distributed in the default locales package, and only the desired locales are compiled on the target system.
After selecting the locales into /etc/locale.gen (via dpkg package configuration, for example), locale-gen is run to compile them via localedef(1).
--keep-existing
Do not remove /usr/lib/locale/locale-archive, only compiling new locales.
/etc/locale.gen
Whitespace-separated newline-delimited locale charset list of locales to build with # start-of-line comments.
12 releases since Debian 3.0 (Woody); the text changed 5 times.
--keep-existing since Debian 12 (Bookworm).
--aliases until Debian 3.1 (Sarge);
--archive until Debian 3.1 (Sarge);
--help until Debian 3.1 (Sarge);
--no-archive until Debian 3.1 (Sarge);
--purge until Debian 3.1 (Sarge).