Git basics

Jun
01
2016
By abernal

Install git in ubuntu

sudo apt-get install git

Check git installation

git --version

Configure preferences

git config --global user.name "alejandrobernalcollazos"
git config --global user.email alejandro@alejandrobernalcollazos.com
git config --global core.editor vim
git config --global merge.tool kdiff3

In these configurations

  • Editor : vim
  • Merge tool : kdiff3
    • must be installed with this command
      • sudo apt-get install kdiff3

To check the preferences

git config --list​

Disable push to multiple branches

git config --global push.default simple
git config --global rerere.enabled true

Initialize a repository

git init

Add new files to the staging area

git add .

Check status

git status

Short version of git status

git status -s

Commit changes to the staging area

git commit -m "First commit"

Change last commit message

git commit --amend

​Ignore files

There are several ways to ignore files, one of them is with the .gitignore file, but there are others and there is also a level of precedence, so for more information please check this reference

Creating a .gitignore file

This method is used to share the "patterns" which should be version-controlled and distributed to other repositories via clone

1. Create a file within the repository's folder called .gitignore (it could be one or more files, however a single file at the root of the repository is good enough)

user@repositoryRoot $ touch .gitignore

2. Add the lines (could be patterns) that specify which sort of files you want to ignore, as a sample lets ignore all the files with .bin extension

*.bin

Define Patterns at $GIT_DIR/info/exclude​ file

This method is used to exclude auxiliary files that live inside the repository but are specific to one user’s workflow

1. Edit the file $GIT_DIR/info/exclude, where $GIT_DIR is the path to the git repository

vim $GIT_DIR/info/exclude

2. Add the lines (could be patterns) that specify which sort of files you want to ignore, as a sample lets ignore all the files with .bin extension

# no .a files
*.a

# but do track lib.a, even though you're ignoring .a files above
!lib.a

# only ignore the TODO file in the current directory, not subdir/TODO
/TODO

# ignore all files in the build/ directory
build/

# ignore doc/notes.txt, but not doc/server/arch.txt
doc/*.txt

# ignore all .pdf files in the doc/ directory
doc/**/*.pdf

Commit with -a

The -a option will allow us to commit all staged and unstaged changes in our local repository

git commit -a -m "Message"

Checkout

This command will pull a given resource (file or files) from the HEAD of the repository

Differences

To see the difference of the changes at the working directory compared to the local repository

git diff

To see the difference of the changes at the staging aread compared to the local repository (staged or cached)

git diff --staged

also

​git diff --cached

To see the difference between remote repository branch and local branch

Suppose we have

  • Remote repo name in localhost : origin
  • Remote repo branch : branch1
  • Local branch : branch1
git diff origin/branch1 ^branch1

Check status of your local git repository

git status

Skipping the staging area

The -a parameter allow us to skip the staging area, making a commit from the working area to the local repository directly

git commit -a -m "Some commit"

Note : Only already tracked files will be commited, if there are file untracket those need to be added first to the staging area and commited to earn the tracked status

Removing Files

Once the next command is executed the "file to be removed" will be gone and no longer tracked

git rm <file to be remoted>

If there are changes in the staging area, in order to remove a file we must

git rm -f <file to be removed>

To remove a file (someFile.txt) but keep it in the working area

git rm --cached someFile.txt

To remove a set of things (This will remove all .log files under log folder)

​git rm log/\*.log

​Rename a file

git mv file_current_name file_new_name

Logs

git log

Show difference at each commit, this will print all commit

​git log -p

Show difference at the last two commits

git log -p -2

Show difference summarizing the changes

git log --stat

Show the logs in one line

git log --pretty=oneline

Configure an upstream reference to a remote repository

HTTP method

git remote add upstream https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY.git

​SSH method

git remote add upstream github@github.com:ORIGINAL_OWNER/ORIGINAL_REPOSITORY.git

Remove remote repo

git remote rm upstream

Patch

Make a patch file from a commit

git format-patch -1 <sha>

​Apply a patch file

git apply file.patch

Disallow push to a remote repository

Suppose we have a remote repository reference called upstream

git remote set-url --push upstream disallowed

Stash

Save the currently unstaged and uncommited changes to a temporary directory

git stash

Pop the last stashed change into the currenty directory

git stash pop

Clear the stash queue

git stash clear

Checkout remote branches

Sample

git checkout -b test origin/test

Clean the working directory

Revert changes

git checkout .

Revert a change already commited

git revert ...

Remove untracked files

git clean -f

Remove untracked files and directories

git clean -fd

​Private Repository

Clone a private repository through https

  • username : abernalc
  • path          : /accout/repoName
​git clone https://abernalc@github.com/accout/repoName

​Extract a subfolder from a Repository into an independent Repository

Reference

1. Clone the original repository
2. Using filter-branch to just have the files of the subfolder

  • folder path : FOLDER-PATH
  • branch       : BRANCH-NAME
git filter-branch --prune-empty --subdirectory-filter FOLDER-PATH  BRANCH-NAME

3. Add the upstream repository

  • username : ABERNALC
  • repository : REPOSITORY
git remote add upstream https://github.com/ABERNALC/REPOSITORY.git

4. Push the code to the new upstream repository

git push -u upstream BRANCH-NAME

5. If you want to return to the current state of the original branch

git checkout <BRANCH>
git reset --hard <COMMIT NUMBER>

​Create a new repository on the command line

echo "# alejandrobernalcollazos" >> README.md
git init
git add README.md
git commit -m "first commit"
git remote add origin https://github.com/abernalc/alejandrobernalcollazos.git
git push -u origin master

​Push an existing repository from the command line

git remote add origin https://github.com/abernalc/alejandrobernalcollazos.git
git push -u origin master
git

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