context-color

🌈 To each context its own shell color

context-color is a simple script that, when executed, outputs a color based on a command output's hash.

Example

Once installed somewhere in your $PATH, it allows you to do things like this:

PS1="$(context-color -p)$PS1\[\e[0m\]"

(where --prompt/-p is the switch so that the color is escaped for prompts, and \[\e[0m\] the escape sequence to reset color)

If your prompt does not use colors already, this example would customize it so that its color changes according to the current context.

The default context command (i.e. the command that is used to generate the hash) is whoami; hostname. If you would just want the color to change according to the hostname, you would change the CC_CONTEXT environment variable (export CC_CONTEXT="hostname") or simply use the --context/-c option (context-color -c "hostname").

Then you could make this customization permanent by adding this line to your ~/.bashrc, or to the system-wide bashrc file (most likely somewhere in /etc/, depending on your distribution) if you would want all users to benefit from this.

If you are working with several machines, you could either do that manipulation on every host, or use something like Russell91/xxh.

⚠️ Do not use single quotes around your PS1 value. If you want the color to be evaluated at each prompt, you should use PROMPT_COMMAND instead. Here is an example:
PS1="$PS1\[\e[0m\]"
PROMPT_COMMAND="context-color"

Install

Something in those lines should do it:

cd .local/bin/
wget https://raw.githubusercontent.com/ramnes/context-color/master/context-color
chmod a+x context-color

This snippet assumes that ~/.local/bin/ is in your $PATH environment variable. If it is not, you can either put context-color somewhere else (/usr/local/bin/, for example), or insert ~/.local/bin/ into your $PATH, by adding this line into your bash configuration:

export PATH="~/.local/bin/:$PATH"

Usage

usage: context-color [OPTIONS]

Print a color sequence based on a command output's hash.

COMMON OPTIONS:
    --help, -h          Print this help.
    --background, -b    Use a background sequence rather than foreground.
    --id, -i            Print the color id rather than the color sequence.
    --prompt, -p        Declare the sequence as non-printable for prompts.

    --context <command>, -c <command>
                        Define the context command on which result the color
                        will be generated.
                        The default context is "whoami; hostname".

    --exclude <colors>, -e <colors>
                        Comma separated list of color ids not to be used.
                        Multiple --exclude/-e arguments can be specified.
                        The default excluded colors are: "0,7,15"

    --method <method>, -m <method>
                        Choose which hashing method to use. "sum" will tend to
                        give adjacent colors for adjacent context outputs.
                        "md5sum" will give more randomization on colors.
                        The default method is: "sum"

DEBUG OPTIONS:
    --debug, -d         Output the sequence as a human-readable string and more
                        useful information.
    --force <color>, -f <color>
                        Ignore the context and force a color id instead.

The -p option must be used if you use context-color inside a prompt. It makes your shell understand that the color sequence characters won't be used when it's trying to guess the space left on the current line. See issue #8 for a good description of what happens if you do not put -p in that situation.

Credits

The original implementation was based on J Earls answer on this SuperUser question.

He's the real MVP. 👌

License

GNU GPL v3