Component

systemd

Is your feature request related to a problem? Please describe

For serial TTYs sessions $TERM environment variable is currently hardcoded to vt220 value.
This is not the best choice for most of the users (among other inconsistencies, they don't get colors by default).

Describe the solution you'd like

Nowadays, most major terminals support XTGETTCAP (Request Termcap/Terminfo String) feature:

DCS + q Pt ST
Request Termcap/Terminfo String (XTGETTCAP), xterm. The
string following the "q" is a list of names encoded in
hexadecimal (2 digits per character) separated by ; which
correspond to termcap or terminfo key names.
A few special features are also recognized, which are not key
names:

• Co for termcap colors (or colors for terminfo colors), and
• TN for termcap name (or name for terminfo name).
• RGB for the ncurses direct-color extension.
  Only a terminfo name is provided, since termcap
  applications cannot use this information.

That could be used by systemd in the session init to acquire for actual $TERM value used by particular terminal on the other end of the serial TTY.
With fallback to the hardcoded value, as previous.

Continuation of #33707.
@poettering

The systemd version you checked that didn't have the feature you are asking for

systemd 256 (256.7-1.fc41)