Gitting things done. Hands-on introduction to git niceties. Jan Urbański Ducksboard

Transcription

1 Gitting things done Hands-on introduction to git niceties Jan Urbański Ducksboard Atlassian Git Party, Madrid, September 25, 2012 Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

2 For those following at home Getting the slides Git version used $ git --version git version Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

3 1 What makes a distributed VCS 2 Common operations 3 Workflows 4 Fun with git Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

4 Outline What makes a distributed VCS 1 What makes a distributed VCS 2 Common operations 3 Workflows 4 Fun with git Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

5 What makes a distributed VCS Indepentent instances every copy of the repository is standalone no central server, no one true version democracy at its best! Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

6 What makes a distributed VCS No revision numbers each repository is independent no central authority to assign revision numbers everything is identified by hashes (commits, files, everything) each hash is built from the object s data and its parent s hash both a consistency and a security measure Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

7 What makes a distributed VCS Full control over the repository you have access to everything you can change past versions of files you can change the ownership of commits it s free for all, until you start sharing the repo Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

8 Initial setup What makes a distributed VCS Configuring Git $ git config --global user.name "Joe H. Hacker" $ git config --global user. "joehacker@example.org" $ git config --global color.diff true $ git config --global color.status true $ git config --global color.branch true $ git config --global color.ui true Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

9 Outline Common operations 1 What makes a distributed VCS 2 Common operations 3 Workflows 4 Fun with git Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

10 Checking in changes Common operations Modify files, register changes $ sed -i s/advanced/awesome/ README $ git status... # modified: README... $ git diff --word-diff $ git add README $ git commit -m "fix the README" Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

11 Common operations Working area, index, repository working area is what s on your filesystem index is what you are indenting to commit repository is what s committed sounds complicated, but is quite useful Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

12 Using the index Common operations Moving changes between the index and the working area $ git add -p $ git status $ git reset $ git status $ git checkout README $ git status Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

13 Using the stash Common operations Stashing and unstashing changes $ sed -i s/awesome/superb/ README $ git stash $ git stash list $ git stash pop $ git diff $ git stash $ git stash apply $ git stash list $ git checkout. $ git stash drop Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

14 Common operations Branches and tags a branch is a chain of commits a tag is a pointer to a single commit branches are quick and cheap to create Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

15 Using branches Common operations Creating and switching branches $ git branch $ git checkout -b my-tests $ git branch $ sed -i s/awesome/great/ README $ git add. $ git commit -m refix the README $ git checkout master $ cat README $ git checkout -b my-other-tests $ sed -i s/awesome/cool/ README $ git commit -a -m different way to fix the README Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

16 A visual example Common operations e a (...) c d e' Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

17 Common operations Forensics all history is stored locally, of course makes consulting it very quick powerful ways of consulting the history Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

18 Using git log Common operations Trolling in repo history $ git log $ git show $ git log -p $ git log --stat $ git log -- src/pl/plpython $ time git log --oneline wc -l $ git log --grep= Urba[nń]ski $ git log -p -S int64 Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

19 Viewing differences Common operations Less and more fancy ways of creating diffs $ git diff $ git diff master..my-tests $ HASH=$(git log --until master@{1 year ago}.. \ -n 1 --pretty=%h) $ echo $HASH $ git diff --stat $HASH.. $ git log master~ src/backend/replication $ git diff master~ src/backend/replication Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

20 Bisecting Common operations Tracking down a behaviour change $ cat src/backend/catalog/sql_features.txt $ cat cat ~/bisect.sh [ -f src/backend/catalog/sql_features.txt ] exit 125! grep -q ^T131.*YES src/backend/catalog/sql_features.txt $ git bisect start master 1b3d400cac1 $ git bisect run ~/bisect.sh $ git show 294e7945 $ git blame src/backend/catalog/sql_features.txt $ g show 294e7945^:src/backend/catalog/sql_features.txt $ g show 294e7945:src/backend/catalog/sql_features.txt Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

21 Outline Workflows 1 What makes a distributed VCS 2 Common operations 3 Workflows 4 Fun with git Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

22 Workflows Remote repositories a remote is a pointer to a different repository you can push your commits to a remote or you can pull commits from a remote to your local repository otherwise, it s just like a branch Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

23 Cloning a repository Workflows Ways of cloning an existing repository $ cd /tmp $ git clone pg-clone1 ~/src/pg $ git clone pg-clone2 ~/src/pg $ git clone $ # git clone username@example.org:pg.git $ cd pg-clone1 $ git remote $ git branch -r Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

24 Adding commits Workflows Pushing commits upstream $ cd /tmp/pg-clone1 $ git checkout --track origin/my-tests $ git branch $ git wtf $ sed -i s/postgresql/postgres/g README $ git add. $ git commit -m change project name $ git wtf $ git push Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

25 Workflows Fetching upstream changes Pulling changes from upstream $ cd /tmp/pg-clone2 $ git checkout --track origin/my-tests $ git wtf $ git fetch $ git wtf $ git log origin/my-tests $ git merge origin/my-tests Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

26 Workflows Merging vs rebasing if only upstream has new commits, straightforward if both upstream and you have commits, needs a decision either perform a merge or rebase your commits Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

27 Workflows Merging vs rebasing - before merging a b c d d' e e' Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

28 Workflows Merging vs rebasing - after merging a b c d d' e e' f Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

29 Workflows Merging vs rebasing - after rebasing a b c d e d' e' Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

30 Merging and conflicts Workflows Creating a conflict $ cd /tmp/pg-clone1 $ sed -i s/http/https/g README $ git add. $ git commit -m improving security $ git push $ cd /tmp/pg-clone2 $ sed -i s/information/info/g README $ git add. $ git commit -m be more concise Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

31 Merging changes Workflows Resolving a conflict when merging $ git push! [rejected] HEAD -> my-tests (non-fast-forward) $ git log origin/my-tests $ git fetch $ git log origin/my-tests $ git wtf $ git pull CONFLICT (content): Merge conflict in README $ $EDITOR README $ git add README $ git commit $ git log --graph Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

32 Merging changes cont. Workflows Resolving a conflict when rebasing $ git reset ORIG_HEAD $ git checkout README $ git rebase origin/my-tests CONFLICT (content): Merge conflict in README $ $EDITOR README $ git add README $ git rebase --continue $ git log --graph Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

33 Merging changes cont. Workflows Autoresolved conflicts $ git reset --hard origin/my-tests^ $ sed -i s/postgres/pg/g README $ git add. $ git commit -m be more concise $ git pull --rebase $ git push Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

34 Outline Fun with git 1 What makes a distributed VCS 2 Common operations 3 Workflows 4 Fun with git Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

35 Custom commands Fun with git Aliases, manual config editing $ git config --global alias.st status $ git config --global alias.ci commit $ git config --global alias.cdiff diff --cached $ git wtf $ cat ~/.gitconfig $ cat ~/src/pg/.git/config Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

36 Rewriting history Fun with git Fixing old commits before pushing $ git ci --amend $ sed -i s/supported/usefull/ README $ git add README $ git ci -m change README $ sed -i s/post/post README $ git add README $ git ci -m change case in product name $ sed -i s/usefull/useful/ README $ git add README $ git ci -m fix ortography, oh the shame! $ git rebase -i origin/master $ cat ~/bin/git-fixup Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37

37 Fun with git Thanks! Questions? Let s grab a beer. Jan Urbański (Ducksboard) Gitting things done Atlassian Git Party / 37