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Git Command Overview

Nathan Schneider, 2012-02-13

General notes on using the git version control system based primarily on a newbie's reading of the Pro Git book. and offer free Git repository hosting.

References and tutorials

(updated 2018-02-06)

Initial configuration

When configuring Git for the first time on a machine, I do the following:

$ git config --global "Nathan Schneider"
$ git config --global " email address..."
$ git config --global core.editor emacs
$ git config --global color.ui true

Local repositories

One of the fundamental things to know about git is that every repository (or copy thereof) contains the complete history of all its files. Each version of every file is stored in full, not as a diff. All git has to keep track of is which file versions were current after any given commit. The overall repository “version” after a commit is represented with a SHA-1 hash checksum.

Starting a new repository in the current directory

git init

Viewing history

git log shows the history of commit messages; add -p to see the changes in each commit


Files in the working directory can be in the following states:


   0. not handled by Git


  1. modified or deleted: known to Git (in SVN terms, part of the “working copy”) but different from the committed file
  2. staged: among the batch of files (or more precisely, file versions) slated to be committed
    • staging a file, then modifying it, then committing will commit the version of the file at the time of staging, not the latest version!
  3. committed: permanently part of the repository

Changing file states

  • {0,1} → 2: git add <file>
  • 2 → 3: git commit [-m <message>]
  • {1,2} → 3: git commit -a [-m <message>]
  • (if -m option is omitted, the configured text editor will open for a commit message to be entered)
  • 2 → 0 (when a previously untracked file was unintentionally staged with git add): git reset <file>

Redoing the previous commit

git commit --amend

Checking status

git status

Removing a file

git rm <file> (stages the removal to git, and if the file remains in working directory, removes it)

Moving a file

git mv <file>

Putting aside local modifications that have not yet been committed, reverting the working directory to the committed version

git stash [save]

Restoring local modifications that have been stashed

git stash apply

Undoing changes in a previous commit

git revert <revision>, e.g. git revert HEAD to undo the most recent commit. Note that reverting an earlier commit will retain the changes made in any subsequent commits.

  • cf. git commit --amend (above) and git rebase, though these are not advised for commits that have been made public

Branching and merging

As visualized here, a branch is simply a pointer to a commit record, which in turn points to a snapshot of files (so branching is cheap). One can locally create and switch among multiple branches. The default branch for a new project is called master. As commit records have backpointers to the record of the previous commit from the same repository, all prior history is available with respect to a given branch.

Branch management

Create a branch pointing to the current snapshot of files

git branch <branch-name>

Delete a branch (deletes the pointer, not the files)

git branch -d <branch-name>

View branch descriptions

git branch -v

Switching branches

A special pointer, HEAD, keeps track of the current branch. You can switch to a newly created branch or back to an old one.

  • If changing to a branch that points to an older commit, git checkout effectively reverts the tracked files in the repository directory to an older snapshot. But the newer versions of these files can later be recovered by switching back to the other branch.
  • If the working directory or staging area has uncommitted changes, these must (normally) be dealt with prior to changing to another branch.

Change the current branch, and "swap" to the snapshot of files that it represents

git checkout <branch-name>

Create a new branch based on an existing one (by default, the HEAD branch) and change to it in one step

git checkout -b <new-branch-name> [<source-branch-name>]

What a commit does, in terms of branches

Crucially, the commit operation creates a new commit record whose parent is the commit record pointed to by the current (HEAD) branch, and then advances the current branch to point to this new record.


Merging is the process of incorporating one branch's changes into another branch. Let H denote the current (HEAD) branch and B another branch that is to be merged into it. There are three cases:

  • If B is an ancestor of H in the commit hierarchy, this has no effect—the current branch already incorporates the changes that were made in B. (TODO: CHECK)
  • If H is an ancestor of B in the commit hierarchy, this is called a fast forward: H will be advanced to point to the same snapshot as B.
  • Otherwise, a three-way merge takes place: git will attempt to create a new snapshot X automagically based on the snapshots of H, B, and their nearest common ancestor. X will have the snapshots of H and B as parents, and then H will be advanced to point to X.
    • If a merge conflict occurs, it can be manually resolved by editing the conflicted files and then using the git add operation on them; or, git mergetool will provide a graphical alternative. Then commit to finalize the merge.

Merging a specified branch B into the current branch

git merge B

It is recommended to create branches frequently—including "topic branches" representing specific changes to the codebase (such as individual bug fixes). These can be worked on in parallel and then merged back into the master branch when they are done.

"Moving" the sequence of commits in the current branch so they depend on the latest version of the base branch B (details)

git rebase B


Tags refer to a specific point in history. This point is fixed for any given tag, unlike with branches, which are typically used to track ongoing development (i.e. the branch advances through history as commits/merges are applied to it).

Remote repositories

Remotes are a mechanism for keeping pointers to repositories at specified URLs. The pointer pairs an alias with a URL.

Cloning (~ SVN “checking out”) a repository so you have a local copy

git clone git://

  • By default, git will add a remote called origin, obtain the origin/master branch, and create and switch to a local master branch pointing to the same version as origin/master.

Changing to a remote branch

see git checkout above

Adding a remote (i.e. a pointer to a remote repository)

git remote add <remote-alias> <URL>

Listing remotes

git remote -v

Getting data from a remote

git fetch [<remote-alias>] (updates remote branches but not local branches; by default, all remote-tracking branches will be updated)

  • To update the local branch that is tracking the remote branch, follow with a merge, or instead use get pull
  • TODO: unclear on difference between git fetch and get fetch --all. Is it that in the former only remote-tracking branches that currently exist locally will be updated? Or is it that in the former only the "current" remote is updated?

Getting and merging data from a remote

git pull [<remote-alias>] (equivalent to a fetch followed by a merge)

Pushing data to a remote

git push [<remote-alias> <local-branch-name>[:<remote-branch-name>]] (remote branch name defaults to the local branch name)

Browsing a remote

git remote show <remote-alias>

Changing the alias to a remote

git remote rename <remote-alias> <new-alias>

Removing a pointer to a remote

git remote rm <remote-alias>

Summary of key commands

  • init, clone for creating a new local repository (respectively, from scratch or from a repository at another location)
  • add, stash, commit, rm, mv for changing the contents of a snapshot in a local repository
  • branch, merge, rebase for updating the structure of the local repository
  • remote for managing connections to a remote repository and its branches
  • checkout for switching to another branch (local or remote)
  • fetch, pull (= fetch + merge), push for sharing changes between the local and remote repositories

Other notes


These are subdirectories within a repository that automatically sync with another repository, e.g. for external libraries. (details: 1, 2)

Referring to specific revisions (commits) or ranges of revisions


Tracing changes

git blame [-L <start-line>,<end-line>] <file> shows the requested lines of the file along with commit history for those lines

git bisect is an interactive tool for narrowing down when a bug was introduced by checking out older revisions and allowing the user to determine and indicate whether the bug is present (1, 2)

Maintaining a private repository from which mature code is released to a public repository




Summarizes the most important functions of the git version control software.



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