珍惜生命，远离技术

git learning tips

git

1. config git

config git initially
ping@640g-laptop:~$ git config --global user.name "ping"
ping@640g-laptop:~$ git config --global user.email "songpingemail@gmail.com"
ping@640g-laptop:~$ git config --global color.status auto
ping@640g-laptop:~$ git config --global color.branch auto

git config --global core.excludesfile ~/.gitignore
git config
ping@640g-laptop:~$ git config --list
user.name=ping
user.email=songpingemail@gmail.com
color.status=auto
color.branch=auto
check config file: .gitconfig
ping@640g-laptop:~$ less .gitconfig
[user]
        name = ping
        email = songpingemail@gmail.com
[color]
        status = auto
        branch = auto
make git ignore some dirs/files (useful!)
ping@640g-laptop:~$ echo "bin" > .gitignore

2. init/addfile/commit git

create some test folders/files
ping@640g-laptop:~$ mkdir temp-git
ping@640g-laptop:~$ cd temp-git/
ping@640g-laptop:~/temp-git$ mkdir datafiles
ping@640g-laptop:~/temp-git$ touch test01
ping@640g-laptop:~/temp-git$ touch test02
ping@640g-laptop:~/temp-git$ touch test03
ping@640g-laptop:~/temp-git$ touch datafiles/data.txt
ping@640g-laptop:~/temp-git$ ls > test01

ping@640g-laptop:~/temp-git$ tree -s
.
|-- [       4096]  datafiles
|   `-- [          0]  data.txt
|-- [         31]  test01
|-- [          0]  test02
`-- [          0]  test03

1 directory, 4 files
init git: git init
ping@640g-laptop:~/temp-git$ git init
Initialized empty Git repository in /home/ping/temp-git/.git/
add all curr files/folders: git add file/folder(s)
ping@640g-laptop:~/temp-git$ git add .
commit the change: git commit -m <msg>
ping@640g-laptop:~/temp-git$ git commit -m "Initial commit"
[master (root-commit) 9c2ed13] Initial commit
 1 files changed, 4 insertions(+), 0 deletions(-)
 create mode 100644 datafiles/data.txt
 create mode 100644 test01
 create mode 100644 test02
 create mode 100644 test03

3. check git log/diff

check the log:git log
ping@640g-laptop:~/temp-git$ git log

commit 9c2ed13c92dec39e193d8311ad180104cb211f46
Author: ping <songpingemail@gmail.com>
Date:   Mon Apr 2 15:13:06 2012 -0400

Initial commit
induce some changes and check the changes
ping@640g-laptop:~/temp-git$ echo "This is a change" > test01
ping@640g-laptop:~/temp-git$ echo "and this is another change" > test02

ping@640g-laptop:~/temp-git$ git diff
diff --git a/test01 b/test01
index 749eb2d..d0a432b 100644
--- a/test01
+++ b/test01
@@ -1,4 +1 @@
-datafiles
-test01
-test02
-test03
+This is a change
diff --git a/test02 b/test02
index e69de29..552c22e 100644
--- a/test02
+++ b/test02
@@ -0,0 +1 @@
+and this is another change

4. Commit the changes

-a will commit changes for modified files but will not add automatically new files

git commit -a -m "These are new changes"

ping@640g-laptop:~/temp-git$ git commit -a -m "These are new changes"
[master e2712e9] These are new changes
 2 files changed, 2 insertions(+), 4 deletions(-)

5. Status, Diff and Commit Log

Make some changes in the file
echo "This is a new change" > test01
echo "and this is another new change" > test02
See the current status of your repository (which files are changed / new / deleted)
ping@640g-laptop:~/temp-git$ git status
# On branch master
# Changed but not updated:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#
#       modified:   test01
#       modified:   test02
#
    no changes added to commit (use "git add" and/or "git commit -a")
Show the differences between the uncommitted files and the last commit in the

current branch

git diff
diff --git a/test01 b/test01
index d0a432b..18fec42 100644
--- a/test01
+++ b/test01
@@ -1 +1 @@
-This is a change
+This is a new change
diff --git a/test02 b/test02
index 552c22e..307d61a 100644
--- a/test02
+++ b/test02
@@ -1 +1 @@
-and this is another change
+This is another new change
Add the changes to the index and commit
git add . && git commit -m "More chaanges - typo in the commit message"
ping@640g-laptop:~/temp-git$ git add . && git commit -m "More chaanges - typo in the commit message"
[master 8e12be3] More chaanges - typo in the commit message
 2 files changed, 2 insertions(+), 2 deletions(-)
Show the history of commits in the current branch
git log
commit 8e12be35dc5ae1bb10960329c74cd0d85e40616c
Author: ping <songpingemail@gmail.com>
Date:   Mon Apr 2 16:16:36 2012 -0400
More chaanges - typo in the commit message
commit e2712e95caa0f5f3853a976c2073b566fa712bc3
Author: ping <songpingemail@gmail.com>
Date:   Mon Apr 2 16:11:02 2012 -0400
These are new changes
commit 9c2ed13c92dec39e193d8311ad180104cb211f46
Author: ping <songpingemail@gmail.com>
Date:   Mon Apr 2 15:13:06 2012 -0400
Initial commit

6. git amend:Correction of commit messages: git commit --amend -m <msg>

The git amend command makes it possible to change the last commit message. In the above example the commit message was incorrect as it contained a typo. The following will correct this via the --amend parameter.

    ping@640g-laptop:~/temp-git$ git commit --amend -m "More changes - now correct"
    [master 17944b3] More changes - now correct
     2 files changed, 2 insertions(+), 2 deletions(-)

    ping@640g-laptop:~/temp-git$ git log
    commit 17944b32e93fafaa33a6c75ff98201d263601538
    Author: ping <songpingemail@gmail.com>
    Date:   Mon Apr 2 16:16:36 2012 -0400

        More changes - now correct

    commit e2712e95caa0f5f3853a976c2073b566fa712bc3
    Author: ping <songpingemail@gmail.com>
    Date:   Mon Apr 2 16:11:02 2012 -0400

        These are new changes

    commit 9c2ed13c92dec39e193d8311ad180104cb211f46
    Author: ping <songpingemail@gmail.com>
    Date:   Mon Apr 2 15:13:06 2012 -0400

        Initial commit

7. Delete files

Create a file and put it under version control
touch nonsense.txt
git add . && git commit -m "a new file has been created"
Remove the file
rm nonsense.txt

Try standard way of committing — This will not work

git add . && git commit -m "a new file has been created"
Now commit all: -a
git commit -a -m "File nonsense.txt is now removed"
-a, --all Tell the command to automatically stage files that have been modified and deleted, but new files you have not told git about are not affected.
man git-commit
Alternatively you could add deleted files to the staging index via:
git add -A .
git commit -m "File nonsense.txt is now removed"
-A, --all Like -u, but match <filepattern> against files in the working tree in addition to the index. That means that it will find new files as well as staging modified content and removing files that are no longer in the working tree.
man git-add

8. Clone your repository

Create a new repository in a new directory via the following commands.

# Switch to home
cd ~
# Make new directory
mkdir repo02

# Switch to new directory
cd ~/repo02
# Clone
git clone ../remote-repository.git .

ping@640g-laptop:~/temp-git$ mkdir ../temp-git2
ping@640g-laptop:~/temp-git$ cd ../temp-git2
ping@640g-laptop:~/temp-git2$ git clone ../temp-remote-repository.git .
Initialized empty Git repository in /home/ping/temp-git2/.git/

9. Setting up a remote (bare) Git repository

remote git repos: git clone --bare

We will now create a remote Git repository.

Git allows you to store this remote repository either on the network or locally.

A standard Git repository is different from a remote Git repository .

A standard Git repository

contains the source code and the Git repository.

You can work directly in this directory as the repository contains a working copy of all files.

A Remote repositories

DO NOT contain working copies of the files. They only contain repository files.

To create such a repository, set the --bare flag.

In order to simplify the following examples, the Git repository will be created locally in the filesystem.

Switch to the first repository
cd ~/repo01
git clone --bare . ../remote-repository.git

10. Push changes to another repository

Make some changes and push them from your first repository to the remote repository via the following commands.

Make some changes in the first repository
cd ~/repo01
Make some changes in the file
echo "Hello, hello. Turn your radio on" > test01
echo "Bye, bye. Turn your radio off" > test02
commit
git commit -a -m "Some changes"
ping@640g-laptop:~/temp-git$ git commit -am "Some Changes"
[master 6d181d6] Some Changes
 2 files changed, 2 insertions(+), 2 deletions(-)
Push the changes
git push ../remote-repository.git

ping@640g-laptop:~/temp-git$ git push ../temp-remote-repository.git/
Counting objects: 7, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (4/4), 396 bytes, done.
Total 4 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (4/4), done.
To ../temp-remote-repository.git/
   17944b3..6d181d6  master -> master

11. lable "origin"

You can always push to a Git repository via its full URL. But you can also add a "shortname" to a repository via the git remote add command.

origin is a special name which is normally used automatically, if you clone a Git repository. Origin indicates the original repository from which you started. As we started from scratch, this name is still available.

Add ../remote-repository.git with the name origin
git remote add origin ../remote-repository.git
Again some changes
echo "I added a remote repo" > test02
Commit
git commit -a -m "This is a test for the new remote origin"
If you do not label a repository it will push to origin
git push origin

12. Show the existing remote repositories

To see the existing definitions of the remote repositories, use the following command.

Show the existing defined remote repositories:git remote
ping@640g-laptop:~/temp-git$ git remote
origin

13. Pull changes

Pull allows you to get the latest changes from another repository. In your second repository, make some changes, push them to your remote repository and pull these changes to your first repository.

original example
# Switch to home
cd ~

# Switch to second directory
cd ~/repo02

# Make changes
echo "A change" > test01

# Commit
git commit -a -m "A change"

# Push changes to remote repository
# Origin is automatically maintained as we cloned from this repository
git push origin

# Switch to the first repository and pull in the changes
cd ~/repo01
git pull ../remote-repository.git/

# Check the changes
less test01
my test logs
ping@640g-laptop:~/temp-git2$ echo "A change" > test01
ping@640g-laptop:~/temp-git2$ git commit -a -m "A change"
[master 42230df] A change
 1 files changed, 1 insertions(+), 1 deletions(-)

ping@640g-laptop:~/temp-git2$ git push origin
Counting objects: 5, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 326 bytes, done.
Total 3 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (3/3), done.
To /home/ping/temp-git2/../temp-remote-repository.git
   d0c385f..42230df  master -> master

ping@640g-laptop:~/temp-git2$ less ../temp-remote-repository.git/test01
../temp-remote-repository.git/test01: No such file or directory

ping@640g-laptop:~/temp-git2$ cd ../temp-git
ping@640g-laptop:~/temp-git$ git pull ../temp-remote-repository.git/
remote: Counting objects: 5, done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 3 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (3/3), done.
From ../temp-remote-repository
 * branch            HEAD       -> FETCH_HEAD
Updating d0c385f..42230df
Fast-forward
 test01 |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

ping@640g-laptop:~/temp-git$ less test01
A change

14. Revert Changes

If you create files in your working copy which you do not want to commit, you can discard them.

# Create a new file with content
touch test04
echo "this is trash" > test04
# Make a dry-run to see what would happen
# -n is the same as --dry-run
git clean -n
# Now delete
git clean -f
#also remove dir
git clean -fd
my test:
ping@640g-laptop:~/temp-git$ touch test04
ping@640g-laptop:~/temp-git$ echo "this is trash" > test04
ping@640g-laptop:~/temp-git$ ls
datafiles  test01  test02  test03  test04
ping@640g-laptop:~/temp-git$ git clean -n
Would remove test04
ping@640g-laptop:~/temp-git$ ls
datafiles  test01  test02  test03  test04
ping@640g-laptop:~/temp-git$ git clean -f
Removing test04
ping@640g-laptop:~/temp-git$ ls
datafiles  test01  test02  test03

15. check out via commitID

You can check out older revisions of your source code via the commit ID. The commit ID is shown if you enter the git log command. It is displayed behind the commit word.

# Switch to home
cd ~/repo01
# Get the log
git log

# Copy one of the older commits and checkout the older revision via
git checkout commit_name
my test
ping@640g-laptop:~/temp-git$ git checkout 9c2ed13c92dec39e193d8311ad180104cb211f46
Note: checking out '9c2ed13c92dec39e193d8311ad180104cb211f46'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

  git checkout -b new_branch_name

HEAD is now at 9c2ed13... Initial commit

ping@640g-laptop:~/temp-git$
ping@640g-laptop:~/temp-git$ less test01
datafiles
test01
test02
test03

If you have not added the changes to the staging index, you can also revert the changes directly.

#Some nonsense change
echo "nonsense change" > test01
#Not added to the staging index. Therefore we can just checkout the old version
git checkout test01
# Check the result
cat test01

# Another nonsense change
echo "another nonsense change" > test01
# We add the file to the staging index
git add test01
# Restore the file in the staging index
git reset HEAD test01                           1
# Get the old version from the staging index
git checkout test01
1 why?

You can also revert commits via the following command:

Revert a commit
git revert commit_name

If you deleted a file but you have not yet added it to the index or committed the change, you can check out the file again.

Delete a file
rm test01
Revert the deletion
git checkout test01

If you added a file to the index but do not want to commit the file, you can remove it from the index via the git reset file command.

// Create a file
touch incorrect.txt
// Accidently add it to the index
git add .
// Remove it from the index
git reset incorrect.txt
// Delete the file
rm incorrect.txt

If you deleted a directory and you have not yet committed the changes, you can restore the directory via the following command:

git checkout HEAD -- your_dir_to_restore

16. Tagging in Git

Git has the option to tag certain versions in the history so that you find them more easily at a later point in time. Most commonly, this is used to tag a certain version which has been released.

You can list the available tags via the following command:
git tag

You can create a new tag via the following. Via the -m parameter, you specify the description of this tag.

git tag version1.6 -m 'version 1.6'

If you want to use the code associated with the tag, use:

git checkout <tag_name>

#test
ping@640g-laptop:~/temp-git$ git tag
ping@640g-laptop:~/temp-git$ git tag version1.6 -m 'version 1.6'
ping@640g-laptop:~/temp-git$ git tag
version1.6
ping@640g-laptop:~/temp-git$ git checkout version1.6
HEAD is now at 9c2ed13... Initial commit
ping@640g-laptop:~/temp-git$

17. Branches and Merging

17.1. Branches

Git allows you to create branches, e.g. independent copies of the source code which can be changed independently from each other. The default branch is called master. Git allows you to create branches very fast and cheap in terms of resource consumption. Developers are encouraged to use branches frequently.

lists all locally available branches. currently active branch is marked with *.
git branch
all branches (including remote branches)
git branch -a
create a new branch via the following.
# Syntax: git branch <name> <hash>
# <hash> in the above is optional
# if not specified the last commit will be used
# If specified the corresponding commit will be used
git branch testing
# Switch to your new branch
git checkout testing
# Some changes
echo "Cool new feature in this branch" > test01
git commit -a -m "new feature"
# Switch to the master branch
git checkout master
# Check that the content of test01 is the old one
cat test01
my test
ping@640g-laptop:~/temp-git$ git branch
* (no branch)
  master
ping@640g-laptop:~/temp-git$ git branch -a
* (no branch)
  master
  remotes/origin/master
ping@640g-laptop:~/temp-git$ git branch testing
ping@640g-laptop:~/temp-git$ git checkout testing
Switched to branch 'testing'
ping@640g-laptop:~/temp-git$ echo "cool new feature in this branch" > test01
ping@640g-laptop:~/temp-git$ git checkout master
error: You have local changes to 'test01'; cannot switch branches.
ping@640g-laptop:~/temp-git$ git commit -am "new feature"
[testing 8380236] new feature
 1 files changed, 1 insertions(+), 4 deletions(-)
ping@640g-laptop:~/temp-git$ git checkout master
Switched to branch 'master'
ping@640g-laptop:~/temp-git$ cat test01
A change

17.2. Delete a branch

To delete a branch which is not needed anymore; you can use the following command.

Delete branch testing
git branch -d testing
Check if branch has been deleted
git branch

17.3. Merging

Merge allows you to combine the changes of two branches. Merge performs a so-called three-way-merge between the latest snapshot of two branches, based on the most recent common ancestor of both. As a result, you have a new snapshot. You can merge changes from one branch to the current active one via the following command.

# Syntax: git merge <branch-name>
git merge testing

If a merge conflict occurs Git will mark the conflict in the file and the programmer has to resolve the conflict manually. After resolving it, he can add the file to the staging index and commit the change.

17.4. Solving merge conflicts

A merge conflicts occurs, if two people have modified the same content and Git cannot automatically determine how both changes should be applied.

Git requires that merge conflicts are solved manually. In this section; we will first create a merge conflict and then resolve it and apply the change to the Git repository.

The following will create a merge conflict.

cd ~/repo01                     # Switch to the first directory
touch mergeconflict.txt         # Make changes
echo "Change in the first repository" > mergeconflict.txt
git add . && git commit -a -m "Will create merge conflict 1"
                                # Stage and commit

cd ~/repo02                     # Switch to the second directory
touch mergeconflict.txt         # Make changes
echo "Change in the second repository" > mergeconflict.txt
git add . && git commit -a -m "Will create merge conflict 2"
                                # Stage and commit

git push                        # Push to the master repository

# Now try to push from the first directory
cd ~/repo01                     # Switch to the first directory
git push                        # Try to push --> will get an error message
git pull origin master          # Get the changes

Git marks the conflict in the affected file. This file looks like the following.

<<<<<<< HEAD
Change in the first repository
=======
Change in the second repository
>>>>>>> b29196692f5ebfd10d8a9ca1911c8b08127c85f8
my testing:
ping@640g-laptop:~/temp-git$ touch mergeconflict.txt
ping@640g-laptop:~/temp-git$ echo "Change in the first repository" > mergeconflict.txt
ping@640g-laptop:~/temp-git$ git add . && git commit -a -m "Will create merge conflict 1"
[master 8de3801] Will create merge conflict 1
 1 files changed, 1 insertions(+), 0 deletions(-)
 create mode 100644 mergeconflict.txt

ping@640g-laptop:~/temp-git$ cd ../temp-git2
ping@640g-laptop:~/temp-git2$ touch mergeconflict.txt
ping@640g-laptop:~/temp-git2$ echo "Change in the second repository" > mergeconflict.txt
ping@640g-laptop:~/temp-git2$ git add . && git commit -a -m "Will create merge conflict 2"
[master a57ae5d] Will create merge conflict 2
 1 files changed, 1 insertions(+), 0 deletions(-)
 create mode 100644 mergeconflict.txt
ping@640g-laptop:~/temp-git2$ git branch
* master
ping@640g-laptop:~/temp-git2$ git push
Counting objects: 4, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 405 bytes, done.
Total 3 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (3/3), done.
To /home/ping/temp-git2/../temp-remote-repository.git
   42230df..a57ae5d  master -> master

ping@640g-laptop:~/temp-git2$ cd ../temp-git
ping@640g-laptop:~/temp-git$ git push
To ../temp-remote-repository.git
 ! [rejected]        master -> master (non-fast-forward)
error: failed to push some refs to '../temp-remote-repository.git'
To prevent you from losing history, non-fast-forward updates were rejected
Merge the remote changes before pushing again.  See the 'Note about
fast-forwards' section of 'git push --help' for details.

ping@640g-laptop:~/temp-git$ git pull origin master
remote: Counting objects: 4, done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 3 (delta 0), reused 0 (delta 0)
Unpacking objects: 100% (3/3), done.
From ../temp-remote-repository
 * branch            master     -> FETCH_HEAD
Auto-merging mergeconflict.txt
CONFLICT (add/add): Merge conflict in mergeconflict.txt
Automatic merge failed; fix conflicts and then commit the result.

ping@640g-laptop:~/temp-git$ less mergeconflict.txt
<<<<<<< HEAD
Change in the first repository
=======
Change in the second repository
>>>>>>> a57ae5ddbf4d38abfc50bfccdf2c9859a394afbd

The above is the part from your repository and the below one from the remote repository. You could now edit the file manually and then commit the changes. Alternatively, you could use the git mergetool command. git mergetool starts a configurable merge tool that displays the changes in a split screen.

git mergetool           #Either edit the file manually or use

ping@640g-laptop:~/temp-git11$ git mergetool
merge tool candidates: opendiff kdiff3 tkdiff xxdiff meld tortoisemerge
gvimdiff diffuse ecmerge p4merge araxis bc3 vimdiff emerge
No files need merging

# You will be prompted to select which merge tool you want to use
# For example on Ubuntu you can use the tool "meld"
# After  merging the changes manually, commit them

git commit -m "merged changes"

18. Rebase

18.1. Rebasing commits in the same branch

The rebase command allows you to combine several commits into one commit. This is useful as it allows the user to rewrite some of the commit history (cleaning it up) before pushing your changes to a remote repository. The following will create several commits which should be combined at a later point in time.

# Create a new file
touch rebase.txt

# Add it to git
git add . && git commit -m "rebase.txt added to index"

# Do some silly changes and commit
echo "content" >> rebase.txt
git add . && git commit -m "added content"
echo " more content" >> rebase.txt
git add . && git commit -m "added more content"
echo " more content" >> rebase.txt
git add . && git commit -m "added more content"
echo " more content" >> rebase.txt
git add . && git commit -m "added more content"
echo " more content" >> rebase.txt
git add . && git commit -m "added more content"
echo " more content" >> rebase.txt
git add . && git commit -m "added more content"

# Check the git log message
git log

We will combine the last seven commits. You can do this interactively via the following command.

git rebase -i HEAD~7

This will open your editor of choice and let you edit the commit message or squash/ fixup the commit with the last one.

Squash will combine the commit messages while fixup will disregard the commit message.

18.2. Rebasing branches

You can also use Git to rebase two branches. As described; the merge command combines the changes of two branches. Rebase takes the changes of a branch, creates a patch and applies it to another branch.

The final result for the source code is the same as with merge but the commit history is cleaner; the history appears to be linear.

# Create new branch
git branch testing
# Checkout the branch
git checkout testing
# Make some changes
echo "This will be rebased to master" > test01
# Commit into testing branch
git commit -a -m "New feature in branch"
# Rebase the master
git rebase master

18.3. Best practice for rebase

You should always check your local branch history before pushing changes to another Git repository or review system.

Git allows you to do local commits. This feature is frequently used to have points to which you can go back, if something should go wrong later during a feature development. If you do so you, before pushing, should look at your local branch history and validate, whether or not these commits are relevant for others.

If they all belong to the implementation of the same feature you, most likely, want to summarize them in one single commit before pushing.

The interactive rebase is basically rewriting the history. It is safe to do this as long as the commits have not been pushed to another repository. This means commits should only be rewritten as long as they have not been pushed.

If you rewrite and push a commit that is already present in other Git repositories, it will look as if you implemented something that somebody already implemented in the past.

18.4. Create and apply patches

A patch is a text file that contains changes to the source code. This file can be sent to someone else and this person can use this file to apply the changes to his/her local repository.

The following creates a branch, makes some changes in this branch, creates a patch and applies the patch to the master.

# Create a new branch
git branch mybranch
# Use this new branch
git checkout mybranch
# Make some changes
touch test05
# Change some content in an existing file
echo "New content for test01" >test01
# Commit this to the branch
git add .
git commit -a -m "First commit in the branch"

# Create a patch --> git format-patch master
git format-patch origin/master
# This created patch 0001-First-commit-in-the-branch.patch

# Switch to the master
git checkout master

# Apply the patch
git apply 0001-First-commit-in-the-branch.patch
# Do your normal commit in the master
git add .
git commit -a -m "Applied patch"

# Delete the patch
rm 0001-First-commit-in-the-branch.patch

19. Define alias

An alias in Git allows you to setup your own Git command. For example, you can define an alias which is a short form of your own favorite commands or you can combine several commands with an alias.

For example, the following defines the git add-commit command which combines git add . -A and git commit -m. After defining this command, you can use it via the git add-commit -m "message" command.

git config --global alias.add-commit !git add . -A && git commit

Unfortunately, defining an alias is at the time of writing this not completely supported in msysGit. You can do single aliases, e.g. ca for ca = commit -a) but you can’t do ones beginning with !.

20. Untrack a file / directory

Sometimes you want to have files or directories not being included in your Git repository. If you add it to your .gitignore file, Git will stop tracking it from this moment. It will not remove it from the repository. Thus, the last version will still be in git. To untrack a file or directory in Git you can use.

# Remove directory .metadata from git repo
git rm -r --cached .metadata
# Remove file test.txt from repo
git rm --cached test.txt

This will not remove the file from the commit history. If the file should also be removed from the history, have a look at git filter-branch which allows you to rewrite the commit history.

21. Other useful commands

The following lists a few Git commands that are useful in the daily work with Git.

Table 2. Useful Git Commands

Command Description git blame filename Who created / modified the file git checkout -b mybranch master~1 Creates a new branch based on the master branch without the last commit

22. Installing a Git server

As described before, you don’t need a server. You can just use a file system or a public Git provider, such as Github or Bitbucket. Sometimes, however, it is convenient to have your own server, and installing it under Ubuntu is relatively easy.

First make sure you have installed ssh.

apt-get install ssh

If you have not yet installed Git on your server, you need to do this too.

sudo apt-get install git-core

Create a new user for git.

sudo adduser git

Now log on with your Git user and create a bare repository.

# Login to server
# to test use localhost
ssh git@IP_ADDRESS_OF_SERVER

# Create repository
git init --bare example.git


Now you can commit to the remote repository.


mkdir gitexample
cd gitexample
git init
touch README
git add README
git commit -m 'first commit'
git remote add origin git@IP_ADDRESS_OF_SERVER:example.git
git push origin master

23. Online remote repositories

23.1. Cloning remote repositories

Git also support remote operations. Git supports several transport types; the native protocol for Git is also called git.

The following will clone an existing repository via the Git protocol.

git clone git@github.com:vogella/gitbook.git

Alternatively you could clone the same repository via the http protocol.

# The following will clone via HTTP git clone http://vogella@github.com/vogella/gitbook.git

23.2. Add more remote repositories

If you clone a remote repository, the original repository will automatically be called origin.

You can push changes to this origin repository via git push origin . Of course, pushing to a remote repository requires write access to this repository.

You can add more remote repositories to your repository via the git remote add name gitrepo command. For example if you cloned the repository from above via the Git protocol, you could add the http protocol via:

Add the https protocol

git remote add githttp https://vogella@github.com/vogella/gitbook.git

23.3. Remote operations via http and a proxy

It is possible to use the HTTP protocol to clone Git repositories. This is especially helpful, if your firewall blocks everything except http.

Git also provides support for http access via a proxy server. The following Git command could, for example, clone a repository via http and a proxy. You can either set the proxy variable in general for all applications or set it only for Git.

This example uses environment variables.

# Linux
export http_proxy=http://proxy:8080
# On Windows
# Set http_proxy=http://proxy:8080
git clone http://dev.eclipse.org/git/org.eclipse.jface/org.eclipse.jface.snippets.git
# Push back to the origin using http
git push origin

This example uses the Git config settings.


// Set proxy for git globally
git config --global http.proxy http://proxy:8080
// To check the proxy settings
git config --get http.proxy
// Just in case you need to you can also revoke the proxy settings
git config --global --unset http.proxy

24. Git Hosting Provider

Instead of setting up your own server, you can also use a hosting service. The most popular Git hosting sites are GitHub and Bitbucket. Both offer free hosting with certain limitations.

24.1. GitHub

GitHub can be found under the URL https://github.com/. GitHub is free for all public repositories, i.e. if you want to have private repositories which are only visible to people you select, you have to pay GitHub a monthly fee.

GitHub requires you to create an ssh key. A description for creating an ssh key in Ubuntu can be found in the ssh key creation in Ubuntu webpage. For Windows please see msysgit ssh key generation .

Create an account at GitHub and create a repository. After creating a repository at GitHub you will get a description of all the commands you need to execute to upload your project to GitHub. Follow the instructions.

These instructions will be similar to the following:

Global setup:
Set up git
git config --global user.name "Your Name"
git config --global user.email your.email@gmail.com
Next steps:
mkdir gitbook
cd gitbook
git init
touch README
git add README
git commit -m 'first commit'
git remote add origin git@github.com:vogella/gitbook.git
git push -u origin master

Existing Git Repo?
cd existing_git_repo
git remote add origin git@github.com:vogella/gitbook.git
git push -u origin master
my test&notes

cd bin git init git add . git commit -m my commit #now go to github website and create a repo manually, say mybin git remote set-url origin https://github.com/pinggit/mybin.git #list the current remote git remove -v git push -f origin master

Username for 'https://github.com': pinggit
Password for 'https://pinggit@github.com':
To https://github.com/pinggit/mybin.git
 + ca88f88...9fc59a7 master -> master (forced update)

#to delete, for now only from website

24.2. Bitbucket

Bitbucket can be found under the URL https://bitbucket.org/. Bitbucket allows unlimited public and private repositories, while the number of participants for one private repository is currently limited to 5 collaborators. I.e. if you have more then 5 developers which need access to a private repository you have to pay money to Bitbucket.

25. Graphical UI’s for Git

This tutorial focused on the usage of the command line for Git. After finishing this tutorial, you may want to look at graphical tools for working with Git.

Git provides two graphical tools. gitk shows the history and git gui shows an editor that allows you to perform Git operations.

The Eclipse EGit project provides Git integration into Eclipse, which is included in the latest Eclipse release.

25.1. gitk

gitk --all

26. Get the Kindle edition

This tutorial is available for your Kindle.

27. git cmds,options sums

.cmds          options                 examples
git-config     --global                git config --global user.name "ping"
                                       git config --global user.name "ping"
                                       git config --global user.email "a@b.us"
                                       git config --global color.status auto
                                       git config --global color.branch auto
--list                  git config --list
git-init                               git init
git-add                                git add .
               std commit,
               not RMed file
               -A
git-logs                               git log
git-status
git-commit     -a                      git commit -a -m "new changes"
                   commit chg/RMed f
                   ,but no new file
               -m
               --amend                 git commit --amend -m "chg corrected"
 git-diff                               git diff
 git-clone      --bare                  git clone --bare rep1 ../remote-rep
                    remote rep
 git-push                               git push origin
 git-pull                               git pull ../temp-git11.r/
 git-clean
                RM untracked Fs
                from working tree
                -n
                    test drive
                -f
                    execute
git-reset                               git reset HEAD file1.txt
git-checkout                            git checkout file1.txt
git-revert
git-branch                              git branch mybranch1
                                        git branch master
                                        git branch -d testing

28. fugitive

29. Questions and Discussion

Before posting questions, please see the vogella FAQ. If you have questions or find an error in this article please use the www.vogella.de Google Group. I have created a short list how to create good questions which might also help you.

30. Links and Literature

Git homepage

EGit - Teamprovider for Eclipse

Video with Linus Torwalds on Git

Progit book - Free Git book

Video casts about Git

http://code.google.com/p/msysgit/ Git on Windows

http://github.com/guides/git-cheat-sheet Git Cheat Sheets

31. real usage cases

to recover the delete file

git reset --hard HEAD

go back to historical version(git essential usev)

¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?commit¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?push¿?¿?¿?¿?¿?¿? ¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿? ¿?¿?¿?¿?¿?git reset¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?reset¿?¿? ¿?¿?¿?¿?git pull¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?¿?merge ¿?¿?¿? ¿?¿?¿?¿?¿?¿?¿?¿? 

git reset --hard 393d3aefc673b01fc26b887c68b57450f1b34178
git push origin master -f
git log:before
ping@640g-laptop:~/mytest-project/jekyll-site/pinggit.github.com$ git log
commit c7ebffb59a0f61281c545743e589b9ce7f0469af
commit c7ebffb59a0f61281c545743e589b9ce7f0469af
Author: ping <songpingemail@gmail.com>
Date:   Sun Feb 24 12:37:54 2013 -0500

    some change

commit b715e0e371ee175c693c55ceb6e9df4111098f65
Author: ping <songpingemail@gmail.com>
Date:   Sun Feb 24 12:26:25 2013 -0500

    change yaml

...<a million more changes here>...

commit 7622dc6f03484be25a4bdc07562a44691bf3bf3c
Author: ping <songpingemail@gmail.com>
Date:   Sun Feb 24 11:57:33 2013 -0500

    change config.yaml

commit 393d3aefc673b01fc26b887c68b57450f1b34178         1
Author: ping <songpingemail@gmail.com>
Date:   Thu Feb 21 16:19:34 2013 -0500

    new post: jekyll - current work flow in vim

  1. target release that we want to go back to

git log:now, looks we lost/trashed all commit info after the target release
commit 393d3aefc673b01fc26b887c68b57450f1b34178
Author: ping <songpingemail@gmail.com>
Date:   Thu Feb 21 16:19:34 2013 -0500

    new post: jekyll - current work flow in vim

commit 64ac9a0becbf4707a6454460601dbf90aa39f056
Author: ping <songpingemail@gmail.com>
Date:   Thu Feb 21 16:18:03 2013 -0500

    new post: usb3.0
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Published

09 April 2013

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