How to change background/font color with prompt (or by hostname?)

[pfaffman]

I work on several different machines. I like to make sure that I know which one I'm looking at. I use Linux.

With some other terminal, I have a script for each machine something like this:

xdotool key --clearmodifiers shift+F10 r 2
ssh -t badboy tmux new -As0

And that switches the terminal to a different color profile (and the connects to the machine and to tmux). I use a separate window for each host and then tmux on each of those.

I would like some way to change the color of the terminal (and the color of the tab) depending on which machine I'm on. I think what I might most like is a way to have the prompt do it. Then, I can just update a shared .bash_aliases to apply it to all my machines.

[andelink]

Does OSC 11 work? OSC 11 ; #hex ST e.g. to set red background:

echo -e "\e]11;#ff0000\e\\"

[00-kat]

This should be the answer. I've also got a more comprehensive one over at #3457 (comment).

(s/echo/printf)

[andelink]

Your linked comment there is a great resource, thanks! The kitty protocol OSC 21 looks far more readable.

s/echo/printf

I see printf being used a lot but is it a strict requirement? echo works for me. My understanding is really anything should as long as it writes to the ${TTY}

[00-kat]

The kitty protocol OSC 21 looks far more readable.

Indeed; though (as per the comments under my comment) it can't be used for this purpose because Ghostty replied even if there was no query which made it unsuitable for putting in e.g. your bashrc. This is fixed now (though it's only on tip, the fix was made after the release was cut).

echo works for me. My understanding is really anything should as long as it writes to the ${TTY}

The issue is:

• Most echos don't parse backslash-escapes without adding the -e flag. The only exception I know is Zsh if the BSD_ECHO option is unset (default).
• POSIX mandates that echo not support any flags, though most implementations disobey POSIX there and echo -e is pretty common, but not universal.

I see printf being used a lot but is it a strict requirement?

In this case the real issue was point one above, but if you had echo -e it's generally fine assuming portability doesn't matter (e.g., your bashrc, which only needs to work on your machine). I typically prefer printf when giving examples though, mostly to raise awareness and also so that I don't get a random comment saying ”this doesn't work on my server running <busybox or something>”.

[andelink]

I see. Thank you for the excellent details. I am indeed a user of zsh on mac, so I live life through the BSD_ECHO filter bubble.

[pfaffman]

Does OSC 11 work? OSC 11 ; #hex ST e.g. to set red background:

echo "\e]11;#ff0000\e\\"

That's almost it, but the -e is required as suggested by @00-kat.

So

echo -e "\e]11;#ff0000\e\\"

Did the trick for me. @andelink can you add the -e to your answer so that it'll be the complete answer?

Now I'll need to track down the code for the foreground.

This will also change the foreground color:

echo -e "\e]11;#2f254e\e\\" "\e]10;#D0CFCC\e\\"

And apologies for not reading @00-kat's answer already linked above!