The Problem
I use the Kitty terminal emulator with Tmux as my main tool for working with code.
My Tmux settings (~/.tmux.conf) contain the following lines to enable true-color-support:
# true colors
set -g terminal-overrides ',xterm-256color:Tc'
set -g default-terminal "tmux-256color"
set -as terminal-overrides ',xterm*:sitm=\E[3m'
When I open tmux on MacOs I get the following error message:
Cannot read termcap database;
using dumb terminal settings.
The Solution
macOS has ncurses version 5.7 which does not ship the terminfo description for tmux.
Download terminfo provided by the tmux maintainers:
curl -sSL https://gist.githubusercontent.com/nicm/ea9cf3c93f22e0246ec858122d9abea1/raw/37ae29fc86e88b48dbc8a674478ad3e7a009f357/tmux-256color > tmux-256color
Follow this guide:
tic -x tmux-256-color
infocmp -x tmux-256color | sed -e 's/pairs#0x10000/pairs#0x1000/' -e 's/pairs#65536/pairs#32768/' > tmux-256color.src
tic -x tmux-256color.src
Verify that terminfo returns the correct value (it should not be null):
infocmp -x tmux-256color