GiTk is a GUI tool written in Tcl/Tk for viewing the Git log as a directed acyclic graph (DAG) and has many features to browse and explore the DAG. This is a tool that ships along with Git, so it should be present wherever Git is there. It accepts many of the options that can be passed to git log.

  • By default, it shows only history of the current branch:
$ gitk
  • Colors: It is important to understand the various colors used in GiTk. Commit with yellow circle is the HEAD. When GiTk is opened, it always jumps to this commit. Commit with red circle is your uncommitted changes. All other commits are shown in blue circle. Local branche names are shown in green, while remote branch names are shown in combination of orange and green with the orange section being the remote name and the green section being the branch name.

  • Configuration file: Configuration settings of this tool can be changed or set in ~/.config/gitk/gitk

  • To view history of another branch:

$ gitk some_other_branch
  • To view the history of all branches:
$ gitk --all
  • To view the history of a certain file:
$ gitk /path/to/file
  • --date-order: Show commits in reverse chronological order of their dates. I use this when I want to get a sense of the progress of the team working on the repository. You might think this is very useful and may wonder why this is not turned on by default. Note that this makes the chain of development harder to visualize. The default view is --topo-order which tries to show as many commits of a branch together as possible. See the man page for an example scenario.

  • --merges: View only the pieces of the DAG with merges.

  • --no-merges: View the disconnected pieces of the DAG with the merge commits removed.

  • --first-parent: Show only the first parent in merges. This greatly simplifies the visual complexity of the DAG. This is especially useful when viewing the DAG of a repository that follows the GitFlow branching model. Note that the first parent of a merge is the branch to which the other branch was merged.

  • -n: Provide a number to this option to limit loading only that many commits. This is useful when viewing a repository with a large number of commits. For example: gitk -n 1000

  • To search and view all the commits with a certain string, type it in the Find box and press Enter. You will see that all the commits with that string are highlighted in bold. You can jump up and down between these commits using the Up and Down arrow buttons at the left.

  • To diff two commits: Click the first commit to highlight it. Next right-click on the second commit to get the context menu and in that menu choose Diff this and selected.

  • F2: To view all the branches and tags in a dialog. Clicking on one of them takes you to that tag or branch. This is useful to navigate a complex DAG.

  • Right-click on any line in the diff shown below and choose Show origin of this line to jump to the commit that added this line. You typically check this on line that are modified or removed in the current commit of course.

  • For complex DAGs, edges are broken into dangling arrowheads. Clicking on the arrow tip jumps you to the other end of the edge.

  • Click on any edge and all the edges that for that segment of the graph are shown in bold. The bottom pane changes to show the parents and children of that piece of the graph.

  • Mark: To bookmark a commit, right-click and choose Mark this commit. The commit will be shown in a box. Marking is useful to bookmark a commit and later return to it. For example, mark a commit, navigate to another part of the DAG and then right-click anywhere and choose Return to mark to go back to the marked commit. It is also useful for diff of two commits. For example, after marking a commit, right-click on another commit and you can choose to diff the two. Only one mark can be set. Setting a new mark, removes the previous one.

  • External Diff: No matter what you are doing in GitK, viewing a commit or comparing two commits, the lower-left box always shows the diffs and the lower-right box the files which are different. However, you may prefer to see diffs side-by-side or using a different external diff viewer, like Meld. This can be done easily. Just right-click any of the filepaths shown in the lower-right box and choose External Diff to view in your favorite diff viewer. The diff program it will use is the one you have set using the diff.tool configuration option in Git.

Tried with: Git 2.4.1 and Ubuntu 14.04

Cannot import name _tkagg


I had Matplotlib installed on a computer. I tried to set the backend for a plot using TkAgg. There was no Tk installed, so I installed the required packages. When I tried to set backend again, I got this error: ImportError: cannot import name _tkagg


Check if your Matplotlib is installed using pip. If so, then you need to reinstall Matplotlib so that it picks up links to the python-tk files correctly:

$ sudo pip uninstall matplotlib
$ sudo pip install matplotlib

The plot was displayed correctly after this.

Tried with: Ubuntu 14.04

Matplotlib plot is not displayed in window


I created a plot using the Matplotlib library in a Python script. But the call to show does not display the plot in a GUI window.


The rendering of a plot to a file or display is controlled by the backend that is set in Matplotlib. You can check the current backend using:

import matplotlib

I got the default backend as Agg. The possible values for GUI backends on Linux are Qt4Agg, GTKAgg, WXagg, TKAgg and GTK3Agg. Since Agg is not a GUI backend, nothing is being displayed.

I wanted to use the simple Tcl-Tk backend. So, I installed the necessary packages for Python:

$ sudo apt install tcl-dev tk-dev python-tk python3-tk

The backend is not set automatically after this. In my Python script, I set it explicitly:

import matplotlib
matplotlib.rcParams["backend"] = "TkAgg"

The plot was displayed after this change.

However, this needs to be set immediately after the import line of Matplotlib and before importing matplotlib.pyplot. Doing this in the import region of a Python script is quite ugly.

Instead, I like to switch the backend of the matplotlib.pyplot object itself:

import matplotlib.pyplot as mplot

This too worked fine for me! 🙂

Reference: Matplotlib figures not showing up or displaying

Tried with: Ubuntu 14.04