Git Tutorial: Practical Git in 1 Hour

# set up default name and email
git config --global user.name "Mary Lee"
git config --global user.email "mary@example.com"

What commands are available?

Type git help to get a list of commonly used git commands.

How to create a project?

cd to your source code dir, then:

1. git init → create a 〔.git〕 dir in the current dir. This dir holds all git's data.
2. git add . → add current dir (and subdir) files into git staging area.
3. git commit -m"first commit" → commit to local repository.

Example:

# cd to the dir containing your code
cd my_project

# initialize. This creates a .git dir.
git init

# add all files to “staging area”
git add .

# commit to local repository.
git commit . -m"my first commit"

Git will create a dir named .git in the same dir. This dir is used by git for all its info, including its database.

Adding 20k files takes ≈6 minutes. Commiting 20k files takes 6 minutes.

How to clone a project?

cd to a directory where you want the files to be, then git clone path or url. Examples:

# get a copy of git source code (≈10MB)
git clone git://git.kernel.org/pub/scm/git/git.git

# get a copy of ErgoEmacs source code (≈18MB)
git clone https://code.google.com/p/ergoemacs/

git clone URL → creates a dir in the current dir with the remote repo's content. The dir will have the same name as the project name of the remote repository at URL.

Note to svn users: git also has a “checkout” command. It's used for updating/reverting your current dir from a repository (a older version, or different branch, etc.). git checkout is similar to svn merge and svn revert.

How to revert a file?

git checkout -- file name

This will update the file file name in working directory. It'll be from your local repository. Effectively, revert whatever you've done to the file.

How to revert a file to a particular version?

git checkout v1.2.3 -- file name         # tag v1.2.3
git checkout stable -- file name         # stable branch
git checkout origin/master -- file name  # upstream master
git checkout HEAD -- file name           # the version from the most recent commit
git checkout HEAD^ -- file name          # the version before the most recent commit

〔How do I revert one file to the last commit in git? 2009-03-28 By Brian Campbell. @ stackoverflow.com…〕

#-------------------
# emacs
*~
*.elc
[#]*[#]

#-------------------
# compiled files
*.com
*.class
*.dll
*.exe
*.o
*.so

#-------------------
# packed files
*.7z
*.dmg
*.gz
*.iso
*.jar
*.rar
*.tar
*.zip

#-------------------
# Logs and databases
*.log
*.sql
*.sqlite

#-------------------
# OS junk
.DS_Store
._*
.Spotlight-V100
.Trashes
Thumbs.db

How to see last changes?

# show diff of last changes
git log -p -2 --color | cat

How to get a history of commits?

Use git log. Example of git log output:

◆ git log
commit a6205ee19e5dd0c049b7fff35de0d09189077594
Author: Xah Lee <xah@xahlee.org>
Date:   Sat Dec 22 04:14:11 2012 -0800

    fixed bug 324

commit c40dc81c7d6ca3d8ad3a4b9996a5b4ed4b0c6d08
Author: Xah Lee <xah@xahlee.org>
Date:   Fri Dec 21 22:29:28 2012 -0800

    changed getinput to not take parameters

Use git log -3 to show just last 3 commits.

This command is important because it shows the ID for each commit. You'll need to use the ID when doing comparisons or diff or revert.

How to tag a version?

git tag "version number or any label"

This will tag the current state of your local repository. (not the index/“staging area”) You probably want to do a commit before you tag.