Check linux/unix terminal color

check_color.sh

awk 'BEGIN{
    s="/\\/\\/\\/\\/\\"; s=s s s s s s s s;
    for (colnum = 0; colnum<77; colnum++) {
        r = 255-(colnum*255/76);
        g = (colnum*510/76);
        b = (colnum*255/76);
        if (g>255) g = 510-g;
        printf "\033[48;2;%d;%d;%dm", r,g,b;
        printf "\033[38;2;%d;%d;%dm", 255-r,255-g,255-b;
        printf "%s\033[0m", substr(s,colnum+1,1);
    }
    printf "\n";
}'

If your terminal support true color (24 bits color), you can see this (Mac iTerm)

if it does not work, you may see something like this (mac default terminal):

How to get true color on Mac?

Install iTerm will work.

How to have true color on linux?

In the linux server, the issue have a good change caused by the screen or tmux.

For screen, looks need to use a higher version (have not check this yet).

For Tmux, add the following to the config file:

~/.tmux.conf

can solve the problem [2]

set -g default-terminal "xterm-256color"

# make colors inside tmux look the same as outside of tmux
# see https://github.com/tmux/tmux/issues/696
# see https://stackoverflow.com/a/41786092
set-option -ga terminal-overrides ",xterm-256color:Tc"

Reference

[1] https://medium.com/@AlexanderObregon/customizing-your-ubuntu-terminal-tips-and-tricks-3f23c746be5a#:~:text=You%20can%20customize%20your%20terminal,the%20text%20and%20background%20colors.

[2] https://unix.stackexchange.com/questions/348771/why-do-vim-colors-look-different-inside-and-outside-of-tmux