Git

What is Git ?

A distributed version control system.

Why Git over SVN ?

1. Github uses git. Most modern IT companies use git.
2. Git is distributed, SVN is centralized. Git enables you to work and source control offline with your own repo.
3. Most operations are done locally, so it’s fast.

How Git works

Git consists of 4 areas:

1. Working Directory: Current working directory.
2. Staging Area: Tracks and saves changes ready to commit.
3. Local Repo: Repository on the disk.
4. Remote Repo: Repository on the server.

Concepts

• HEAD: Current branch.

.gitignore file

Refs:

1. Git ignore patterns
2. gitignore

Patterns

Pattern	Example matches	Explanation
logs	logs logs/debug.log logs/latest/foo.bar build/logs build/logs/debug.log	If you don’t append a slash, the pattern will match both files and the contents of directories with that name. In the example matches on the left, both directories and files named logs are ignored
logs/	logs/debug.log logs/latest/foo.bar build/logs/foo.bar build/logs/latest/debug.log	Appending a slash indicates the pattern is a directory. The entire contents of any directory in the repository matching that name – including all of its files and subdirectories – will be ignored
logs/*	logs/test.log(a file) logs/test(a directory) but not logs/bar/hello.c(a file)	the asterisk in the pattern does not match “bar/hello.c” which has a slash in it.
logs/ !logs/important.log	logs/debug.log logs/important.log	Wait a minute! Shouldn’t logs/important.log be negated in the example on the left? Nope! Due to a performance-related quirk in Git, you can not negate a file that is ignored due to a pattern matching a directory
logs/**/debug.log	logs/debug.log logs/monday/debug.log logs/monday/pm/debug.log	A double asterisk matches zero or more directories.
logs/*day/debug.log	logs/monday/debug.log logs/tuesday/debug.log but not logs/latest/debug.log	Wildcards can be used in directory names as well.
logs/debug.log	logs/debug.log but notdebug.log build/logs/debug.log	Patterns specifying a file in a particular directory are relative to the repository root. (You can prepend a slash if you like, but it doesn’t do anything special.)

FAQ

What is HEAD in git ?

The HEAD in Git is the pointer to the current branch reference, which is in turn a pointer to the last commit you made or the last commit that was checked out into your working directory.

Git reset

Ref

Suppose we have a branch master with A/B/C commits:
- A - B - C (master)

• reset --soft B: Moves pointer to B; changes staged; run commit and will get a new commit as C
• reset --mixed B: Default. moves pointer to B; changes remain but unstaged; run add and commit and will get a new commit as C
• reset --hard B: Moves pointer to B; changes permanently reset; always run status to make sure changes can be discarded

Undo a commit

undo add: git reset
undo commit: git reset --hard HEAD~1 (moves to one commit before and --hard resets staging and working changes)

Links existing directory with remote repo

• In existing directory, git init .
• git remote add origin <remote repo url>(origin is a conventional name for remote repo)
• git push origin <local branch name>

What is a leading slash in .gitignore ?

The leading slash anchors the match to the root.

How can I ignore everything but one file in a directory ?

Original Answer

git add -f Website\bin\Settings.json

What is fast-forward ?

Git pull and git fetch

• Ref: Fetch vs pull
• Git pull: Incorporates changes from a remote repository into current branch and then fast-forward/merge current branch.
• Git fetch: If don’t want to fast-forward/merge, use this.
• pull = fetch + merge

Branches

• git branch
  Show all local branches, with current branch marked with an asterisk.

  * master
  Pages

• git branch -r
  Show all remote branches.

  origin/HEAD -> origin/master  // Currently checked out branch, which is origin/master
  origin/master

• git branch -a
  List all branches.

• git branch newb
  Create new branch named newb.

• git checkout newb
  Switch to branch newb.

• git checkout -b newb
  Shorthand for git branch newb and git checkout newb.

• git branch -d newb
  Delete local branch newb.