Colors are off when running Vim via SSH inside tmux.

[paddor]

I'm using iTerm2 3.0.10 on macOS which connects via SSH to an Ubuntu 14.04 VM running Neovim 0.1.6-dev and Tmux 2.0.

I have the following vim config:

packadd vim-solarized8
colorscheme solarized8_dark
set t_8f=^[[38;2;%lu;%lu;%lum
set t_8b=^[[48;2;%lu;%lu;%lum
set termguicolors

(the ^[ are actual escape sequences)

This works pretty well without Tmux, like this:

But as soon as I start nvim inside Tmux, it looks FUCKED. Like this:

My TERM is xterm-256color outside of tmux, and screen-256color inside.

I've tried pretty much "everything" but no success. Any ideas why?

[lifepillar]

I cannot reproduce that, at least using Vim (I don't have NeoVim in the Ubuntu box I'm connecting to). My Vim configuration is like yours. It sounds like a tmux problem.

This is the terminal configuration in my .tmux.conf, in case it helps:

set -g  default-terminal            "tmux-256color"
set -ga terminal-overrides          ",xterm-256color:Tc"

(I set the terminal to tmux-256color rather than screen-256color because I have custom terminfo files in my home directory).

[lifepillar]

This is a comment from my personal dotfiles repository, when I introduced the lines above:

Setting terminal-overrides seems to be necessary to enable true colors within tmux.

[paddor]

Thanks for the help. Unfortunately adding the two lines (with screen-256color) didn't help. What kind of custom terminfo files do you have there?

[lifepillar]

From ncurses.

brew install ncurses
mkdir -p ~/.terminfo/{74,78}
cp /usr/local/opt/ncurses/share/terminfo/74/tmux-256color ~/.terminfo/74
cp /usr/local/opt/ncurses/share/terminfo/78/xterm-256color ~/.terminfo/78

They give me italics in terminal (also in Terminal.app).

[lifepillar]

Ah, in Ubuntu you should put tmux-256color into ~/.terminfo/t/, not ~/.terminfo/74.

[lifepillar]

Btw, I'm using tmux 2.1, if that matters.

[paddor]

I managed to upgrade to Tmux 2.4 (prerelease I guess?) but I can't easily upgrade ncurses-base to get that tmux-256color file. :( And the xterm one doesn't help either.

[lifepillar]

This is the content of my ~/.terminfo/t/tmux-256color:

tmux-256color|tmux with 256 colors,
        am, hs, km, mir, msgr, xenl,
        colors#256, cols#80, it#8, lines#24, pairs#32767,
        acsc=++\,\,--..00``aaffgghhiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz{{||}}~~,
        bel=^G, blink=\E[5m, bold=\E[1m, cbt=\E[Z, civis=\E[?25l,
        clear=\E[H\E[J, cnorm=\E[34h\E[?25h, cr=^M,
        csr=\E[%i%p1%d;%p2%dr, cub=\E[%p1%dD, cub1=^H,
        cud=\E[%p1%dB, cud1=^J, cuf=\E[%p1%dC, cuf1=\E[C,
        cup=\E[%i%p1%d;%p2%dH, cuu=\E[%p1%dA, cuu1=\EM,
        cvvis=\E[34l, dch=\E[%p1%dP, dch1=\E[P, dim=\E[2m,
        dl=\E[%p1%dM, dl1=\E[M, dsl=\E]0;\007, ed=\E[J, el=\E[K,
        el1=\E[1K, enacs=\E(B\E)0, flash=\Eg, fsl=^G, home=\E[H,
        ht=^I, hts=\EH, ich=\E[%p1%d@, il=\E[%p1%dL, il1=\E[L,
        ind=^J, is2=\E)0, kbs=^H, kcbt=\E[Z, kcub1=\EOD, kcud1=\EOB,
        kcuf1=\EOC, kcuu1=\EOA, kdch1=\E[3~, kend=\E[4~, kf1=\EOP,
        kf10=\E[21~, kf11=\E[23~, kf12=\E[24~, kf2=\EOQ, kf3=\EOR,
        kf4=\EOS, kf5=\E[15~, kf6=\E[17~, kf7=\E[18~, kf8=\E[19~,
        kf9=\E[20~, khome=\E[1~, kich1=\E[2~, kmous=\E[M,
        knp=\E[6~, kpp=\E[5~, nel=\EE, op=\E[39;49m, rc=\E8,
        rev=\E[7m, ri=\EM, ritm=\E[23m, rmacs=^O, rmcup=\E[?1049l,
        rmir=\E[4l, rmkx=\E[?1l\E>, rmso=\E[27m, rmul=\E[24m,
        rs2=\Ec\E[?1000l\E[?25h, sc=\E7,
        setab=\E[%?%p1%{8}%<%t4%p1%d%e%p1%{16}%<%t10%p1%{8}%-%d%e48;5;%p1%d%;m,
        setaf=\E[%?%p1%{8}%<%t3%p1%d%e%p1%{16}%<%t9%p1%{8}%-%d%e38;5;%p1%d%;m,
        sgr=\E[0%?%p6%t;1%;%?%p1%t;3%;%?%p2%t;4%;%?%p3%t;7%;%?%p4%t;5%;%?%p5%t;2%;m%?%p9%t\016%e\017%;,
        sgr0=\E[m\017, sitm=\E[3m, smacs=^N, smcup=\E[?1049h,
        smir=\E[4h, smkx=\E[?1h\E=, smso=\E[7m, smul=\E[4m,
        tbc=\E[3g, tsl=\E]0;,

[paddor]

I upgraded to Ubuntu LTS 16.04 and downgraded tmux to 2.1 and now it kinda works (using screen-256colors terminfo). I have more normal colors, but for some reason, the background is kinda brown? See here:

It's like that even if I comment those few hi lines out. Are your solarized colors by any chance based on ajacksified/vim-colors-solarized-brown?

I prefer the green-ish background.

Oh and thanks for your tmux-256color! Same problem with it though.

[lifepillar]

Are your solarized colors by any chance based on ajacksified/vim-colors-solarized-brown?

No, the color palette is from the original Solarized.

Oh and thanks for your tmux-256color! Same problem with it though.

You may try raising an issue at the tmux repository. I am afraid I have run out of ideas :(

[paddor]

I might do that. Thanks anyway for your help!

[frioux]

FWIW I have the same issue

[lifepillar]

Reopening, because I can now reproduce the issue.

Let me summarise the problem: the issue here is that Vim colors do not look right when

1. you connect to a remote (Ubuntu) box via SSH;
2. you run a tmux session in the remote box;
3. you run an instance of Vim or NeoVim in the remote box, with termguicolors on, and t_8f and t_8b explicitly set.

Besides, your local terminal does support true colors (e.g., iTerm2). The local terminal color palette should not matter. Finally, if you run Vim outside tmux, colors do look fine.

What I have found is that there seems to be a problem with true colors in tmux, which is independent of Vim. To verify that, can you please try the following script both inside and outside tmux?

#!/bin/bash
#
# https://gist.github.com/XVilka/8346728
#
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";
}'

This is what I get outside tmux:

And this is what I get inside tmux:

The commands are run in the remote box, of course. I am using tmux 2.1 in Ubuntu.

[frioux]

Yeah, I agree and was having the same problem with that exact script in tmux. I am sorta confused because it... went away after a reboot? For more details, read here: tmux/tmux#993

[lifepillar]

This discussion seems relevant: tmux/tmux#622. If you use NeoVim, could you try what is suggested in vim-one's Readme?

[lifepillar]

I have updated tmux to v2.5 and the issue is gone. Feel free to reopen this if you still have problems with the latest tmux.

[rieger-jared]

I had this issue as well running tmux 3+. Adding the lines suggested in vim one worked for me.

# Add truecolor support
set-option -ga terminal-overrides ",xterm-256color:Tc"
# Default terminal is 256 colors
set -g default-terminal "screen-256color"

[Hrjfi]

Mantri Mall