GIT Overview – Reviewing history – git log
GIT Overview – Reviewing history – git log
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jcruzmartini.github.io
Slides for Git webcast based on http://patok.github.io/git-introOn Github jcruzmartini / jcruzmartini.github.io
GIT Overview
CONTENT
- Introduction
- Basic Operations
- Branching & merging
- Remote Repositories
- References
- Examples
What is git?
- it's an open source version control system
- goals: speed, simple design, strong support for non-linear development (thousands of parallel branches), fully distributed, able to handle large projects like the Linux kernel efficiently (speed and data size)
- developed as a version control system for Linux in 2005
- created by Linus Torvalds (who also created the Linux kernel)
! another definition: stupid content tracker
SCM Taxonomies
Storage:
- diffs/deltas
- DAG/snapshots
SCM Taxonomies
Deltas vs Snapshots
SCM Taxonomies
By architecture
local: restricted to a local machine centralized: client-server distributed: pair networks, there are multiple in-sync copiesSCM Taxonomies
Taxonomy matrix
Features
local operations (local repository copy, no need to be online): checkouts, commits, branching, history analysis integrity: each object in the database has a hash (SHA1 - 40 hexadecimal digits - criptographycally safe) simple storage structure: always writes data, no updates 3-status files: committed, modified and staged (ready to be committed)File Statuses
Basic Commands
Initializing a repository
-
local initialization
$ git init
-
clone a remote repository
$ git clone git://github.com/schacon/grit.git
.git directory
$ tree .git
.git
|-- config
|-- description
|-- HEAD
|-- hooks
| |-- commit-msg.sample
|-- index
|-- info
| `-- exclude
|-- objects
| |-- info
| `-- pack
`-- refs
|-- heads
`-- tags
Checking the status
nothing to commit
$ git status
# On branch master
nothing to commit (working directory clean)
Checking the status
There are modifications
$ vim README
$ git status
# On branch master
# Untracked files:
# (use "git add <file>..." to include in what will be committed)
#
# README
nothing added to commit but untracked files present (use "git add" to track)
Adding new files
$ git add README
$ git status
# On branch master
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# new file: README
#
Staging modifications
$ git status
# On branch master
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# new file: README
#
# Changed but not updated:
# (use "git add <file>..." to update what will be committed)
#
# modified: benchmarks.rb
#
$ git add benchmarks.rb
$ git status
# On branch master
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# new file: README
# modified: benchmarks.rb
#
Ignoring changes (.gitignore)
$ cat .gitignore
*target/
*.settings/
*.classpath
*.project
*bin/
# a comment - this is ignored
*.a # no .a files
!lib.a # but do track lib.a, even though you're ignoring .a files above
/TODO # only ignore the root TODO file, not subdir/TODO
build/ # ignore all files in the build/ directory
doc/*.txt # ignore doc/notes.txt, but not doc/server/arch.txt
Looking at changes in detail
$ git status
# On branch master
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# new file: README
#
# Changed but not updated:
# (use "git add <file>..." to update what will be committed)
#
# modified: benchmarks.rb
#
$ git diff
diff --git a/benchmarks.rb b/benchmarks.rb
index 3cb747f..da65585 100644
--- a/benchmarks.rb
+++ b/benchmarks.rb
@@ -36,6 +36,10 @@ def main
@commit.parents[0].parents[0].parents[0]
end
+ run_code(x, 'commits 1') do
+ git.commits.size
+ end
+
run_code(x, 'commits 2') do
log = git.commits('master', 15)
log.size
Looking at changes (staged or cached)
$ git diff --cached
diff --git a/README b/README
new file mode 100644
index 0000000..03902a1
--- /dev/null
+++ b/README2
@@ -0,0 +1,5 @@
+grit
+ by Tom Preston-Werner, Chris Wanstrath
+ http://github.com/mojombo/grit
+
+Grit is a Ruby library for extracting information from a Git repository
Committing changes
$ git commit
# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
# On branch master
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# new file: README
# modified: benchmarks.rb
~
~
~
".git/COMMIT_EDITMSG" 10L, 283C
Deleting
$ git rm grit.gemspec
rm 'grit.gemspec'
$ git status
# On branch master
#
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# deleted: grit.gemspec
#
Renaming or moving
$ git mv README.txt README
$ git status
# On branch master
# Your branch is ahead of 'origin/master' by 1 commit.
#
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# renamed: README.txt -> README
#
git is smart enough to detect it when it was not informed
$ mv README.txt README
$ git rm README.txt
$ git add README
Undoing the last commit: commit --amend
$ git commit -m 'initial commit'
$ git add forgotten_file
$ git commit --amend
Undoing changes: reset
Let's suppose...
$ git add .
$ git status
# On branch master
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# modified: README.txt
# modified: benchmarks.rb
#
... and then we want to go back and not to commit benchmarks.rb
$ git reset HEAD benchmarks.rb
benchmarks.rb: locally modified
$ git status
# On branch master
# Changes to be committed:
# (use "git reset HEAD <file>..." to unstage)
#
# modified: README.txt
#
# Changed but not updated:
# (use "git add <file>..." to update what will be committed)
# (use "git checkout -- <file>..." to discard changes in working directory)
#
# modified: benchmarks.rb
#
Reviewing history
git log
$ git log
commit ca82a6dff817ec66f44342007202690a93763949
Author: Scott Chacon <schacon@gee-mail.com>
Date: Mon Mar 17 21:52:11 2008 -0700
changed the version number
commit 085bb3bcb608e1e8451d4b2432f8ecbe6306e7e7
Author: Scott Chacon <schacon@gee-mail.com>
Date: Sat Mar 15 16:40:33 2008 -0700
removed unnecessary test code
commit a11bef06a3f659402fe7563abf99ad00de2209e6
Author: Scott Chacon <schacon@gee-mail.com>
Date: Sat Mar 15 10:31:28 2008 -0700
first commit
</schacon@gee-mail.com></schacon@gee-mail.com></schacon@gee-mail.com>
other alternatives to format the ouput:
$ git log --stat
commit ca82a6dff817ec66f44342007202690a93763949
Author: Scott Chacon <schacon@gee-mail.com>
Date: Mon Mar 17 21:52:11 2008 -0700
changed the version number
Rakefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
commit 085bb3bcb608e1e8451d4b2432f8ecbe6306e7e7
Author: Scott Chacon <schacon@gee-mail.com>
Date: Sat Mar 15 16:40:33 2008 -0700
removed unnecessary test code
lib/simplegit.rb | 5 -----
1 file changed, 5 deletions(-)
commit a11bef06a3f659402fe7563abf99ad00de2209e6
Author: Scott Chacon <schacon@gee-mail.com>
Date: Sat Mar 15 10:31:28 2008 -0700
first commit
README | 6 ++++++
Rakefile | 23 +++++++++++++++++++++++
lib/simplegit.rb | 25 +++++++++++++++++++++++++
3 files changed, 54 insertions(+)
</schacon@gee-mail.com></schacon@gee-mail.com></schacon@gee-mail.com>
shows files and changes statictics
other alternatives to format the ouput:
$ git log -p -2
commit ca82a6dff817ec66f44342007202690a93763949
Author: Scott Chacon <schacon@gee-mail.com>
Date: Mon Mar 17 21:52:11 2008 -0700
changed the version number
diff --git a/Rakefile b/Rakefile
index a874b73..8f94139 100644
--- a/Rakefile
+++ b/Rakefile
@@ -5,5 +5,5 @@ require 'rake/gempackagetask'
spec = Gem::Specification.new do |s|
s.name = "simplegit"
- s.version = "0.1.0"
+ s.version = "0.1.1"
s.author = "Scott Chacon"
s.email = "schacon@gee-mail.com
commit 085bb3bcb608e1e8451d4b2432f8ecbe6306e7e7
Author: Scott Chacon <schacon@gee-mail.com>
Date: Sat Mar 15 16:40:33 2008 -0700
removed unnecessary test code
diff --git a/lib/simplegit.rb b/lib/simplegit.rb
index a0a60ae..47c6340 100644
--- a/lib/simplegit.rb
+++ b/lib/simplegit.rb
@@ -18,8 +18,3 @@ class SimpleGit
end
end
-
-if $0 == __FILE__
- git = SimpleGit.new
- puts git.show
-end
\ No newline at end of file
</schacon@gee-mail.com></schacon@gee-mail.com>
shows diffs between commits, for the last two commits!
Reviewing history
... visual ;-)
Saving the work in progress
Using the stash
$ git status # On branch master # Changes to be committed: # (use "git reset HEAD <file>..." to unstage) # # modified: index.html # # Changes not staged for commit: # (use "git add <file>..." to update what will be committed) # # modified: lib/simplegit.rb # $ git stash save Saved working directory and index state \ "WIP on master: 049d078 added the index file" HEAD is now at 049d078 added the index file (To restore them type "git stash apply")
Using the stash
$ git stash list
stash@{0}: WIP on master: 049d078 added the index file
stash@{1}: WIP on master: c264051 Revert "added file_size"
stash@{2}: WIP on master: 21d80a5 added number to log
$ git stash apply # On branch master # Changes not staged for commit: # (use "git add <file>..." to update what will be committed) # # modified: index.html # modified: lib/simplegit.rb #
Getting help
Help!
$ git help
usage: git [--version] [--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]
[-p|--paginate|--no-pager] [--no-replace-objects] [--bare]
[--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>]
[-c name=value] [--help]
<command></command> [<args>]
The most commonly used git commands are:
add Add file contents to the index
bisect Find by binary search the change that introduced a bug
branch List, create, or delete branches
checkout Checkout a branch or paths to the working tree
clone Clone a repository into a new directory
commit Record changes to the repository
diff Show changes between commits, commit and working tree, etc
fetch Download objects and refs from another repository
grep Print lines matching a pattern
init Create an empty git repository or reinitialize an existing one
log Show commit logs
merge Join two or more development histories together
mv Move or rename a file, a directory, or a symlink
pull Fetch from and merge with another repository or a local branch
push Update remote refs along with associated objects
rebase Forward-port local commits to the updated upstream head
reset Reset current HEAD to the specified state
rm Remove files from the working tree and from the index
show Show various types of objects
status Show the working tree status
tag Create, list, delete or verify a tag object signed with GPG
See 'git help <command></command>' for more information on a specific command.
</args></name></path></path></path>
$ git help status $ git help commit
Branching
What is a branch in Git?
A branch in Git is an agile and movable pointer to a commit. When you create a repository, Git makes a branch that "points" to the last commit. By default has the name of "master". You can create your own branches, from any commit. As you make new commits, that pointer is going to move forward automatically.Simple Branching
A scenario example:
we are working in a project that we have somes commits already we begin to work in a new story and we create a new branch call "iss53" it comes a requirement to solve a high priority bug need to momentarily leave the story to provide a hotfix we create a branch "hotfix", and once we test our fix, must be merge and needs to be deployed in production back to work in the storyHistory of the current project
New branch iss53
$ git checkout -b iss53
Switched to a new branch "iss53"
Commits of the iss53 branch
$ vim index.html
$ git commit -a -m 'added a new footer [issue 53]'
watch how the reference is move forward
Back to master to work in the fix
$ git checkout master
Switched to branch "master"
Git resets your working directory to be the same that the last commit on master.
Create the hotfix branch, and we build the fix
$ git checkout -b 'hotfix'
Switched to a new branch "hotfix"
$ vim index.html
$ git commit -a -m 'fixed the broken email address'
[hotfix]: created 3a0874c: "fixed the broken email address"
1 files changed, 0 insertions(+), 1 deletions(-)
Ready to merge the hotfix into master
$ git checkout master $ git merge hotfix Updating f42c576..3a0874c Fast forward README | 1 - 1 files changed, 0 insertions(+), 1 deletions(-)
Ready to deploy in production and get back to the story!
Fast forwarding branches
A branch that was updated recently by commits, is likely to make fast-forwarding when your commits are ancestors of the new ones.
Back to the story
removing the hotfix branch
$ git branch -d hotfix Deleted branch hotfix (3a0874c).
switch to iss53 branch
$ git checkout iss53 Switched to branch "iss53" $ vim index.html $ git commit -a -m 'finished the new footer [issue 53]' [iss53]: created ad82d7a: "finished the new footer [issue 53]" 1 files changed, 1 insertions(+), 0 deletions(-)
Merging
How can I update master with the new functionality?
$ git checkout master $ git merge iss53 Merge made by recursive. README | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
Merging: trouble case
Git will let you know when cannot merge automatically
$ git merge iss53 Auto-merging index.html CONFLICT (content): Merge conflict in index.html Automatic merge failed; fix conflicts and then commit the result. $ git status index.html: needs merge # On branch master # Changed but not updated: # (use "git add <file>..." to update what will be committed) # (use "git checkout -- <file>..." to discard changes in working directory) # # unmerged: index.html # <<<<<<< HEAD <div id="footer">contact : email.support@github.com</div> ======= <div id="footer"> please contact us at support@github.com </div> >>>>>>> iss53
Merging: trouble case
Must be resolved manually or using some merge tool (mergetool)
$ vim index.html $ git add index.html $ git status # On branch master # Changes to be committed: # (use "git reset HEAD <file>..." to unstage) # # modified: index.html #
Getting branch information
Some useful commands
$ git branch -v iss53 93b412c fix javascript issue * master 7a98805 Merge branch 'iss53' testing 782fd34 add scott to the author list in the readmes
to get local branches
$ git branch --merged iss53 * master
Informs the branches that are merge in the current branch
$ git branch --contains e5c2d6ec * master
prints the branches that has e5c2d6ec commit on...
Branches: common strategies
Branches long stay
Very long life
Branches: common strategies
Branches by topic
Topic branches on the other hand has very short life
Rebasing vs Merge
$ git checkout experiment $ git rebase master First, rewinding head to replay your work on top of it... Applying: added staged command
gets the C3 commit and replicates in the branch generated by the new C3 commit
Remotes repositories
The remotes repositories allows you shared the code, are copies of our objects, to_synchronize_uses:
push, fetch (pull)
Showing remote repos (remote -v)
$ git remote -v origin git://github.com/schacon/ticgit.git
Adding remote repo (remote add)
$ git remote origin $ git remote add pb git://github.com/paulboone/ticgit.git $ git remote -v origin git://github.com/schacon/ticgit.git pb git://github.com/paulboone/ticgit.git
Synchronizing local copy of remote repo (fetch)
$ git fetch pb remote: Counting objects: 58, done. remote: Compressing objects: 100% (41/41), done. remote: Total 44 (delta 24), reused 1 (delta 0) Unpacking objects: 100% (44/44), done. From git://github.com/paulboone/ticgit * [new branch] master -> pb/master * [new branch] ticgit -> pb/ticgit
Pushing/uploading changes in remote repo (push)
$ git push origin master
Remote repo information (remote show)
$ git remote show origin
* remote origin
URL: git://github.com/schacon/ticgit.git
Remote branch merged with 'git pull' while on branch master
master
Tracked remote branches
master
ticgit
Remote Repositories
Examples
Examples
To sum up
Conclusion
- fast and efficient (most used operations are local)
- everyone has a copy, hence there are many backups ;)
- not need to be connected to:
- see file history
- create a new branch or switching branches
- merge code between branches
- code commits
- see differences between versions
- get any version of a file