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I use git on an everyday basis—it’s a powerful tool that supports many different workflows. However, depending on your workflow, there are useful configurations you can set up that make using the tool that much easier.

git really shines when you can make the UI give you a little more information about what’s going on as you work. This can be done with a built-in feature of git called tracking branches.

Tracking Branches

All (well, almost all) branches in git “track” a branch. Usually this branch is a remote branch, like origin/master. However, you can also set up tracking of local branches. One way you can specify that your current branch should track another branch is to run the following:

git branch --set-upstream `git rev-parse --abbrev-ref HEAD`

This gives you the ability to compare the current branch relative to the branch it is tracking, for example, if you are on branch master and it is tracking origin/master, when you make a commit and run git status part of the output will say:

Your branch is ahead of 'origin/master' by 1 commit.

git determines this by finding the common ancestor between the current branch head of master and the head of tracking branch origin/master. Since master has only one commit between its head and the head of origin/master, it returns the above output.

Although rarely used, I’ve found it useful to create a git track alias by adding the above command to the list of aliases in ~/.gitconfig:

[alias]
track = !sh -c 'git branch --set-upstream `git rev-parse --abbrev-ref HEAD` $1' -

This is a little more user-friendly and intuitive for those cases where I explicitly want to set a tracking branch.

Another useful shortcut is a git tracking alias which displays which branch a specified branch is tracking. This is slightly more complicated to do and thus isn’t a one-liner, but here’s the shell script:

#!/usr/bin/env bash

if [ -n "$1" ]; then
local_branch="$1"
else
local_branch=`git symbolic-ref -q HEAD | sed 's/^refs\/heads\///'`
fi

remote_branch=`git config branch.${local_branch}.merge | sed 's/^refs\/heads\///'`
remote=`git config branch.${local_branch}.remote`

if [ "$remote" == "." ]; then
echo ${remote_branch}
else
echo ${remote}/${remote_branch}
fi

If you save this as git-tracking and give it execute permissions, you’ll be able to run it using git tracking.

Notice that if a branch is tracking a local branch (i.e. a branch local to this repository) instead of a remote branch (i.e. a branch on origin), the name of the remote is just ., or in other words the current repository (if you think of . as the similar to ls’s representation of the current directory, it makes sense).

This script works by extracting the tracking branch information using git config, which itself simply reads from the local config file in the .git directory for the repository. Each branch in your repository that has been set to track another branch will have an entry in .git/config that looks something like the following:

[branch "master"]
remote = origin
merge = refs/heads/master

The key points to observe are that this configuration states the local master branch tracks a remote repository called origin, and the branch on it tracks on origin is called master (thus, origin/master).

Set Tracking Branches Automatically

A slightly odd problem with tracking branches is that they aren’t set up automatically when creating a new branch (except for master being set to track origin/master when you first clone a repository). However, this behaviour can be changed so that when you create a new branch it tracks the branch you’re currently on, or the remote branch you pulled from. Add the following to your ~/.gitconfig:

[branch]
autosetupmerge = always

The branch.autosetupmerge setting dictates whether or not git sets up new branches so that they will be mergeable with the starting-point branch (usually the branch you were on before creating the new branch). It basically saves you from having to run the git track alias discussed above.

How Does This Help?

While tracking branches are relatively intuitive to understand, they don’t seem terribly useful as a concept so far. After all, git doesn’t automatically set up these tracking branches in all situations, so why bother making the above change to always set up tracking branches, even for local branches?

This will become apparent in a follow-up post, where I’ll discuss the power of a rebase-based git workflow.

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Shane da Silva


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Shane da  Silva

Coding by the woods

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