Tutorials/Git/git-book.md

Git Book

Git Book

Chapter 1

• Git tracks snapshots, not differences (virtual filesystem)
• Nearly every operation is local
• Has integrity included
• Generally only adds data

Three states

Working Directory	Staging area	.git repository
<=	= checkout=	=<
stage >=	=>
	commit >=	=>

First time setup

• Global: /etc/gitconfig
• Per-user: .gitconfig

• Per-project: .git/config

  $ git config --global user.name "John Doe"
  $ git config --global user.email johndoe@example.com
  $ git config --global core.editor vim
  $ git config --list
  

Get help

• git help 'verb'
• git 'verb' --help
• man git-'verb'

Chapter 2

Getting a Repository

• New repositor: $ git init
• Clone existing: $ git clone https://github.com/libgit2/libgit2 [mygitlib]

Reordering Changes

Untracked	Unmodified	Modified	Staged
add the file >=	==	==	=>
	edit the file >=	=>
		stage the file >=	=>
<=	=< remove the file
	<=	==	=< commit the file

• Checking the status: $ git status
• Adding file(s) $ git add . $ git add README.md $ git add *.c
• Staging modified files $ git add modified.file
• The same file can be staged and unstaged, if it was edited after staging!
• Short status git status -s
  • Left letter: status of the staging area
  • Right letter: status of the working tree
  • ??: untracked
  • A : added to the staging area
  • MM: modified, staged, modified again
  • M: modified, not yet staged
  • M : modified and staged
• ignore files over .gitignore Examples:
  • *.a: no a-files...
  • !lib.a: ...except for lib.a
  • /TODO: ignore TODO in the current directory, but not in other directories
  • build/: ignore all files in the build directory
  • doc/*.txt: ignore txt files in the doc directory
  • doc/**/*.pdf: ignore txt files in doc and all its subdirs

View staged and unstaged changes

• See unstaged changes: $ git diff
• See staged changed: $ git diff --staged or $ git diff --cached

Committing your changes

• Commit staged files: $ git commit or $ got commit -m "my message"
• Skip the staging area: $ git commit -a -m "my message"
  • it's equivalent to git add . followed by $ git commit -m "my message"

Removing files

• $ git rm removes files from the staging area and removes it from the drive.
• if you first remove a file with $ rm the change will be recorded. You must still type $ git rm to remove it from the stage area before committing.
• if you modified a file and already added it to the staging area, you must use -f to force the removal. This is a security feature, because the data couldn't be recovered by git.
• You can remove files from the staging area but keep it on the drive (e.g. if you forgot to put them in .gitignore). $ git rm --cached

Moving files

• Git is smart about file moves. therefore the two options are equivalent:
  • $ git mv a b
  • $ mv a b followed by $ git rm a && git add b

Viewing the history

• Generally with $ git log
• show diffs of changes and limit to last N entries: $ git log -p -N
• show abbreviated stats: $ git log --stat

• use --pretty=keyword option. Keywords are

  • oneline
  • short
  • full
  • fuller

  • format

    $ git log --pretty=format:"%h - %an, %ar : %s"
    %H, %h:   Commit hash, abbrev. commit hash
    %T, %t:   Tree hash, abbrev. tree hash
    %P, %p:   Parent hash, abbrev. parent hash
    %an, %ae: Author name, author email
    %ad, %ar: Author date, author date, relative
    %cn, %ce: Committer name, committer email
    %cd, %cr: Committer date, committer date, relative
    %s:       Subject
    

• Show graph: git log --pretty=format:"%h %s" --graph

• other options:

  • -(n) show only the last n commits
  • --since, --after Limit to commits after a date
  • --until, --before Limit to commits before a date
  • --author Filter by author
  • --committer Filter by committer
  • --grep Filter by content of the commit string
  • -S Only show commits adding or removing code matching the string