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dessert
Asked: 2017-10-23 01:13:27 +0800 CST

`watch git log` with correct colors

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I want to watch the output of git log --oneline --graph with all the colors and tried to adapt the solution from Why don't git colours appear when using watch?, but it just renders (nearly) the whole output in orange:

Output using watch -c

$ watch -c git -c color.diff=always log --graph --oneline

enter image description here

Note how from the first commit hash on everything is printed in orange. This is the output of watch from procps-ng 3.3.10 on Ubuntu 16.04.

Normal output = goal

$ git log --graph --oneline

enter image description here

The output with an additional -c color.diff=always is the same, cat -A shows the ANSI color sequences in use:

$ git -c color.diff=always log --graph --oneline | cat -A
* ^[[33m8ccd905^[[m L
* ^[[33me4ad4f6^[[m E
* ^[[33mf427d2a^[[m U
* ^[[33me8351c8^[[m Z
* ^[[33mf06747c^[[m I

Question

How can I get watch git log to show the colors like git log does?

command-line

3 Answers

  1. Best Answer

    This was a bug in procps-ng (Ubuntu package name procps), fixed in version 3.3.11.

    Latest Ubuntu LTS (16.04 Xenial) still contains the bug, whereas current regular versions (17.04 Zesty and 17.10 Artful) already ship the fixed version.

    • 3

  2. The comment by egmont tells about watch not recognizing ANSI 39 (reset the foreground color only). It is ^[[39m as pointed by WJAndrea. Others have answered that it is a bug in procps-ng.

    In other git commands, like diff, it is noticeable that bold colors work, but any uncolored text that follows keeps the previous color, until a new bold color appears. The reason is that bold colors specify '^[[1;##m'.

    So we known where to focus.

    First I made a quick regex with sed to replace all colors to bold, and was working just fine. It just required a leading bold color, because some git commands output do not start colored and there were a starting regular text until the first color code.

    I tested during this afternoon, and that massive bold text was taking my attention.

    I use i3wm, so I keep some terminals open side by side. And one vivid and colorful terminal watching my git log was starting to be annoying. Before today I was living with a uncolored log :c

    Another problem is that I hard-coded a bold light gray color to replace the uncolored text: people using other color schemes could yell at me.

    To solve all, I changed my initial idea to something simpler. Instead of bolding the text, I just need to add a 0 to make the color code valid to watch. Changed a few characters and voilà! The colors appear as expected, bold texts keep their meaning, and the window hanging around feels better.

    I tested the performance with a huge commit history (>90k commits), and there is a noticeable delay of some milliseconds, if you use the --graph or --date-order flags, and maybe others, but --oneline seems safe. Even asking to log only a few commits gives delay, Git has to process the whole history to generate the graph.

    But that case was extreme. And you don't need a 0.1s update. 3 or 4s looks good. watch -n #

    My current code is the following:

    #!/bin/bash
git -c color.ui=always "$@" | sed -r $'s/\033\[([[:digit:]][[:digit:]])m/\033\[0;\\1m/g; s/\033\[m/\033\[0m/g'

    I saved in ~/bin/git-colored with +x permission and it can be used with git colored <git command>

    Solving the main post: watch -c 'git colored log --oneline --graph'

    I created a gist with this file, where you can see the code history.

    TL;DR

    There is a bug in a Ubuntu package. The one line code above is a workaround for who can not/don't want to upgrade the system, basically doing what is in here.

    • 1

  3. A quick workaround I made if you don't have procps-ng 3.3.11: pipe your git output through sed "s/\x1b\[m/\x1b\[00m/", e.g. for git status:

    watch -c 'git -c color.ui=always status | sed "s/\x1b\[m/\x1b\[00m/"'

    This replaces empty ANSI escapes ([m, not recognized by watch) with zeroed ones ([00m, fully recognized by watch).

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