Chapter_2

Chapter 2

1 - Getting a Git Repository

• git init will turn a project into a git repository
• creates the .git subdirectory
• git add adds files to be tracked by git
• git clone pulls down all the repo data from the server
  • can be used to restore a server in the worst case
• Git can use http(s) or git protocols
  • git protocol uses SSH

2 - Recording Changes

• Tracked files are all that git knows about
• UnTracked files are everything else in the staging area
• git status checks the status of each file in the repo
• git add begins tracking the new file(s)
  • new files are staged
• Once files are modified they will be in the changed but not staged section of the status
• A specific version of a file is staged, so it can be both staged and un-staged at different versions if you make changes to a file after staging it but before commiting the stage
• git status --short is a shortform status
  • Two columns, staging and working directory
  • A means added, M modified, ?? Means untracked file
• .gitignore tells git what files to ignore. Won't show up as untracked
  • Blank lines or # lines are ignored
  • Glob's work
  • start a line with / to avoid recursing
  • end line with / to specify directories
  • Negate a pattern with !
  • file follows a heirarchy like the .gitconfig file
• git diff shows the current diff of the modified changes against the stage (or last commit if the stage is empty)
• git diff --staged shows the diff of the staged changes against the last commit
• git commit commits your stage and lets you view the changes and create a commit message
• git commit -m allows you to specify the commit message on the CLI
• git commit -a automatically stages all tracked files with changes before commiting
  • Allows you to skip the git add step if desired
• git rm removes a files from filesystem and git tracking
• 'git rm --cachedremoves file from staging area but not working tree (so we can keep it locally but likely add it to.gitignore`)
• git mv moves and renames files

3 - Viewing History

• git log shows commits in reverse chronological order
• git log --patch shows the changes in the commit
• git log -<n> limits the output to the last N commits
• git log --stat shows abbreviated stats for each commit
• git log --pretty=<format> allows you to specify commit format for parsing in scripts
• git log --graph shows a graph of merge history, useful with --pretty
• git log --since=<time period> limits to commits since time period
  • Can be a real date or a relative date like "2 years ago"
• git log --until=<time period> as above only commits until the time period
• git log --author=<author> limits commits to certain authors
• git log --grep=<grep string> lets you search commit messages
• git log -S <string> lets you search for commits that changed the number of occurences of that string (usually a function)
• git log <options> -- <path> lets you limit your search for commits to a subdirectory

4 - Undoing

• Undoing is dangerous, sometimes irreversable
• git commit --ammend lets you change a commit
• git reset HEAD <file> unstages a staged file
• git checkout -- <file> throws away working directory changes
• Most things can be recovered, but nothing can be recovered if it never made it into a commit

5 - Remotes

• git remote -v shows remotes with url's
• lets you pull (and sometimes push) with many different collaborators
• git remote add <name> <url> lets you add a remote for fetch and push
• git fetch <remote> gets the data from a remote
• git fetch only downloads the remote data into your local repo, it doesn't merge it
• git pull does a fetch and a merge
• git push <remote> branch pushes your changes up to remote
• git remote show <remote> shows you info about the remote
• git remote rename <remote> <new name> renames a remote
• git remote rm <remote> removes a remote

6 - Tagging

• git tag lists tags
• git tag -l <string> searchs for tags
• tag types
  • lightweight, basically just a branch pointing at a specific commit that can't change
  • annotated ** full objects in database ** contain tagger name, email, date, and message ** recommended way to tag things
• git tag -a <tag name> -m <tag message> tags the current commit as an annotated tag
• git show <tag name> shows the tag info
• git tag <tag name> creates a lightweight tag
  • git show will only show the commit that is referenced the LW tag
• git tag -a <tag name> <commit sha1> tags the specified commit
• tags are not pushed to master automatically
• git push <remote> <tag name> pushes the specified tag to the specified remote
• git push <remote> --tags push all tags to remote
• git tag -d <tag name> delete the specifed tag
• git push <remote> :refs/tags/<tag name> push null (before the colon) to the remote tag name, deleting it
• git push <remote> --delete <tag name> delete the tag on the remote
• git checkout <tag name> checkout the tag in a detached HEAD state
  • A state that is not on a branch
  • If you make a commit it lives nowhere but your local repo and can't be pushed
• git checkout -b <branch> <tag name> checkout the tag to a new branch so you can make and push changes if desired

7 - Aliases

• git config --global alias.<alias name> <command> creates the alias for the specified command
• Run non git commands with a preceding ! IE: git config --global alias.visual '!gitk'

8 - Summary

• Useful commands
  • git add <file|directory>
  • git clone <remote URL>
  • git status
  • git status --short
  • git diff
  • git diff --staged
  • git commit -m <message>
  • git commit -am <message>
  • git rm
  • git rm --cached
  • git log
  • git log --patch
  • git log -<n>
  • git log --stat
  • git log --pretty=<format>
  • git log --graph
  • git log --since=<time period>
  • git log --author=<author>
  • git log --grep=<grep string>
  • git log -S <string>
  • git log <options> -- <path>
  • git commit --ammend
  • git reset HEAD <file>
  • git checkout -- <file>
  • git remote -v
  • git fetch <remote>
  • git pull
  • git push <remote>
  • git remote show <remote>
  • git tag
  • git tag -l <string>
  • git tag -a <tag name> -m <message>
  • git push <remote> <tag name>
  • git push --tags <remote>
  • git tag -d <tag name>
  • git push <remote> --delete <tag name>
  • git config --global alias.<alias name> <command>