Terminal

Truecolor and Italic support

Create a xterm-24bit.terminfo file with the following contents:

xterm-24bit|xterm with 24-bit direct color mode,
   use=xterm-256color,
   sitm=\E[3m,
   ritm=\E[23m,
   setb24=\E[48;2;%p1%{65536}%/%d;%p1%{256}%/%{255}%&%d;%p1%{255}%&%dm,
   setf24=\E[38;2;%p1%{65536}%/%d;%p1%{256}%/%{255}%&%d;%p1%{255}%&%dm,

Make sure you have a newline at end of file otherwise you will get errors!

Execute the following command:

/usr/bin/tic -x -o ~/.terminfo xterm-24bit.terminfo

Now you can set your $TERM variable to xterm-24bit:

export TERM=xterm-24bit

SSH might break if your remote machine does not have the same setup, you can work around this with the following alias.

alias ssh="TERM=xterm-256color ssh"

If you use tmux, you need to make sure you installed a version with truecolor support, then add the following lines to your .tmux.conf:

set -g default-terminal "xterm-24bit"
set -g terminal-overrides ',xterm-24bit:Tc'

For tmux you can also create a variant of the tmux-256color instead of xterm-256color terminfo like so:

$ cat <<EOF > ~/tmux-24bit.terminfo
tmux-24bit|tmux with 24-bit direct color mode,
   use=tmux-256color,
   sitm=\E[3m,
   ritm=\E[23m,
   setb24=\E[48;2;%p1%{65536}%/%d;%p1%{256}%/%{255}%&%d;%p1%{255}%&%dm,
   setf24=\E[38;2;%p1%{65536}%/%d;%p1%{256}%/%{255}%&%d;%p1%{255}%&%dm,
EOF
/usr/bin/tic -x -o ~/.terminfo xterm-24bit.terminfo

and use set -g default-terminal tmux-24bit in ~/.tmux.conf.

Also, make sure you have utf8 language variables if you want all characters to display correctly. For example:

export LC_ALL=en_US.UTF-8
export LANG=en_US.UTF-8
export LANGUAGE=en_US.UTF-8

Emacs 28

Emacs 28 can support 24-bit color TTY without terminfo database by setting COLORTERM=truecolor in the environment.