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Git Out of Trouble

What is Git?

open source
distributed
fast

1.7.10.4

Lion 10.7

iTerm2 command line

git-scm.com/downloads

Other Tools

Trouble

Mistakes

Who gets into trouble?

Uncle Sam

GitHub

Linus Torvalds

Everyone

An Ounce of Prevention

"...an Ounce of Prevention is worth a Pound of Cure...."

Benjamin Franklin

RTFM

$ git help <command>

$ man git-<command>

$ git
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> [<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
...

See 'git help <command>' for more information on a specific command.

Experiment

$ git add --dry-run .
add '.gitignore'
add '.rvmrc'
add 'Gemfile'
...

$ git status
  # On branch master
  #
  # Untracked files:
  #   (use "git add <file>..." to include in what will be committed)
  #
  # .gitignore
  # .rvmrc
  # Gemfile
  ...

But, do wear safety goggles

-n, usually short-hand for --dry-run

$ git help commit
...
-n, --no-verify
           This option bypasses the pre-commit and
           commit-msg hooks. See also githooks(5).
...
--dry-run
           Do not create a commit, but show a list of paths
           that are to be committed, paths with local
           changes that will be left uncommitted and paths
           that are untracked.

A Pound of Cure

Problem

You added a file by mistake

$ git add showoff.json

$ git status
  # On branch master
  # Changes to be committed:
  #   (use "git reset HEAD <file>..." to unstage)
  #
  #        new file:     showoff.json

Solution

RTFC

$ git status
  # On branch master
  # Changes to be committed:
  #   (use "git reset HEAD <file>..." to unstage)
  #
  #        new file:     showoff.json

$ git reset HEAD showoff.json

$ git status
  # On branch master
  # Untracked files:
  #   (use "git add <file>..." to include in what will be committed)
  #
  #        showoff.json

Problem

You removed a file by mistake

$ git rm references/02_slide.md
rm 'references/02_slide.md'

$ ls references/02_slide.md
ls: references/02_slide.md: No such file or directory

$ git status
 # On branch master
 # Changes to be committed:
 #   (use "git reset HEAD <file>..." to unstage)
 #
 #  deleted:    references/02_slide.md
 #

Solution

RTFC

$ git status
 # On branch master
 # Changes to be committed:
 #   (use "git reset HEAD <file>..." to unstage)
 #
 #  deleted:    references/02_slide.md
 #

$ git reset HEAD references/02_slide.md
Unstaged changes after reset:
D   references/02_slide.md

$ git status
 # On branch master
 # Changes not staged for commit:
 #   (use "git add/rm <file>..." to update what will be committed)
 #   (use "git checkout -- <file>..." to discard changes in working directory)
 #
 #  deleted:    references/02_slide.md
 #
 no changes added to commit (use "git add" and/or "git commit -a")

$ git checkout -- references/02_slide.md

$ git status
 # On branch master
 nothing to commit (working directory clean)

$ ls references/02_slide.md
references/02_slide.md

Problem

Some file is cluttering up your status

$ git status
  # On branch master
  # Untracked files:
  #   (use "git add <file>..." to include in what will be committed)
  #
  # .DS_Store
  nothing added to commit but untracked files present (use "git add" to track)

Ignore it!

$ echo .DS_Store >> .gitignore

$ cat .gitignore
.DS_Store

$ git status
  # On branch master
  # Untracked files:
  #   (use "git add <file>..." to include in what will be committed)
  #
  # .gitignore
  nothing added to commit but untracked files present (use "git add" to track)

Problem

You want to ignore a file without updating all repositories

$ git status
  # On branch master
  # Untracked files:
  #   (use "git add <file>..." to include in what will be committed)
  #
  # .DS_Store
  nothing added to commit but untracked files present (use "git add" to track)

Use a global ignore file

$ git config --global core.excludesfile ~/.gitignore

$ cat ~/.gitconfig
...
[core]
        excludesfile = ~/.gitignore

$ echo .DS_Store >> ~/.gitignore

$ cat ~/.gitignore
.DS_Store

$ cat .gitignore

$ git status
  # On branch master
  nothing to commit (working directory clean)

For more on ignore patterns and precendence of ignore files

$ git help gitignore

$ man gitignore

But `.DS_Store` is still everywhere!

You could...

$ find . -type f -name ".DS_Store" -print | xargs rm -rf

$ find . -type d -name ".svn" -print | xargs rm -rf

Mr. Clean

$ git clean

$ git clean -d

Problem

You wrote a bad commit message for the last commit

$ git commit -m "Whatever"
[master 1eaaace] Whatever
 1 file changed, 11 insertions(+)

Solution

Amend it

$ git commit --amend

Whatever

# 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^1 <file>..." to unstage)
#
#   modified:   one/01_slide.md
#

Describe amending commit to fix bad message

# 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^1 <file>..." to unstage)
#
#   modified:   one/01_slide.md
#

Much better

$ git commit --amend
...
[master a4f0c81] Describe amending commit to fix bad message
 1 file changed, 11 insertions(+)

Not just for commit messages

$ git status
  # On branch master
  # Your branch is ahead of 'origin/master' by 4 commits.
  #
  # Changes not staged for commit:
  #   (use "git add <file>..." to update what will be committed)
  #   (use "git checkout -- <file>..." to discard changes in working directory)
  #
  # modified:   one/01_slide.md

$ git commit --amend

Describe amending commit to fix bad message

# 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^1 <file>..." to unstage)
#
#   modified:   one/01_slide.md
#

All changes in one commit

$ git commit --amend
...
[master 57f0ba9] Describe amending commit to fix bad message
 1 file changed, 4 insertions(+)

Caution

$ git commit -m "Whatever"
[master 1eaaace] Whatever
 1 file changed, 11 insertions(+)

$ git commit --amend
[master a4f0c81] Describe amending commit to fix bad message
 1 file changed, 11 insertions(+)

$ git commit --amend
[master 57f0ba9] Describe amending commit to fix bad message
 1 file changed, 4 insertions(+)

When using `--amend`, think locally

Problem

You want to clean up your local branches

$ git branch
  546826_react_to_pgs_callback
  faster_specs
* master
  pgs
  refactor_noaa_decline_reasons

Which branches can I delete?

$ git branch
  546826_react_to_pgs_callback
  faster_specs
* master
  pgs
  refactor_noaa_decline_reasons

$ git branch --merged
  546826_react_to_pgs_callback
* master
  pgs

Which branches should I keep?

$ git branch
  546826_react_to_pgs_callback
  faster_specs
* master
  pgs
  refactor_noaa_decline_reasons

$ git branch --no-merged
  faster_specs
  refactor_noaa_decline_reasons

Bonus: Which branches contain `<commit>`?

$ git branch
  546826_react_to_pgs_callback
  faster_specs
* master
  pgs
  refactor_noaa_decline_reasons

$ git branch --contains
  faster_specs
* master
  refactor_noaa_decline_reasons

Use `git branch`

--merged to find all branches which can be safely deleted
--no-merged to find branches which are candidates for merging into HEAD
--contains <commit> find all branches which will need special attention if <commit> were to be rebased or amended

You want to know what changed in a commit

$ git log -p

commit 8fdd6b1a31ae4eb07ddafa7027c3e54cc4fdc9cc
Author: Craig Demyanovich <cdemyanovich@gmail.com>
Date:   Thu Jun 14 21:21:57 2012 -0500

    Bigger text on using an ignore file

diff --git a/one/01_slide.md b/one/01_slide.md
index a4a3fa7..b2cff87 100644
--- a/one/01_slide.md
+++ b/one/01_slide.md
@@ -235,7 +235,7 @@ command line
       #        .DS_Store
       nothing added to commit but untracked files present (use "git add" to track)

-!SLIDE commandline incremental smaller
+!SLIDE commandline incremental small
 ## Use a global ignore file

     $ git config --global core.excludesfile ~/.gitignore

commit 175c8c3bce2f2901f42ddc8c332b3d101ee2069a
Author: Craig Demyanovich <cdemyanovich@gmail.com>
Date:   Thu Jun 14 21:18:10 2012 -0500

    Better warning about changing SHAs
...

$ git show 175c8c3
commit 175c8c3bce2f2901f42ddc8c332b3d101ee2069a
Author: Craig Demyanovich <cdemyanovich@gmail.com>
Date:   Thu Jun 14 21:18:10 2012 -0500

    Better warning about changing SHAs

diff --git a/one/01_slide.md b/one/01_slide.md
index 3a90275..a4a3fa7 100644
--- a/one/01_slide.md
+++ b/one/01_slide.md
@@ -325,8 +325,10 @@ command line
     [master a4f0c81] Describe amending commit to fix bad message
      1 file changed, 11 insertions(+)

+!SLIDE center
+![Caution](../images/500px-Stop_hand_caution.svg.png)
+
 !SLIDE commandline
-## WARNING: the SHA changed

     $ git commit -m "Whatever"
     [master 1eaaace] Whatever

You pushed a bad commit

$ git commit -am "Killed Mr. Clean"
[master ece75be] Killed Mr. Clean
 1 file changed, 9 deletions(-)

$ git revert ece75be

Revert "Killed Mr. Clean"

This reverts commit ece75be6fa91e135cfc349341aa523d323d92e5b.

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
# On branch master
# Your branch is ahead of 'origin/master' by 2 commits.
#
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#   modified:   one/01_slide.md
#
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#   images/

$ git revert ece75be
...
[master 9791a68] Revert "Killed Mr. Clean"
 1 file changed, 9 insertions(+)

$ git log
commit 9791a68ebe0f454766e0d0a43c1d1e59ea943d01
Author: Craig Demyanovich <cdemyanovich@gmail.com>
Date:   Thu Jun 14 23:37:19 2012 -0500

    Revert "Killed Mr. Clean"

    This reverts commit ece75be6fa91e135cfc349341aa523d323d92e5b.

commit ece75be6fa91e135cfc349341aa523d323d92e5b
Author: Craig Demyanovich <cdemyanovich@gmail.com>
Date:   Thu Jun 14 23:36:59 2012 -0500

    Killed Mr. Clean
...

$ git revert -n ece75be
$ git revert -n c9099b3
...
$ git revert -n 8fdd6b1

$ git commit -am "Reverted a few bad commits"

References

git-scm.com

pragprog.com/book/pg_git/pragmatic-guide-to-git

Pragmatic Guide to Git

git-scm.com/book

(free)

Pro Git

pragprog.com/book/tsgit/pragmatic-version-control-using-git

Pragmatic Version Control Using Git

help.github.com

GitHub Help

`cheat` gem

cheat.errtheblog.com/

$ gem install cheat
Fetching: cheat-1.3.0.gem (100%)
Successfully installed cheat-1.3.0
1 gem installed

$ cheat git

git:
  Setup
  -----

  git clone <repo>
    clone the repository specified by <repo>; this is similar to "checkout" in
    some other version control systems such as Subversion and CVS

  Add colors to your ~/.gitconfig file:

    [color]
      ui = auto
  ...

https://github.com/icefox/git-achievements

Git Achievements

gitimmersion.com/

Git Immersion

Git Out of Trouble

What is Git?

git-scm.com/downloads

Trouble

Who gets into trouble?

An Ounce of Prevention

RTFM

Experiment

But, do wear safety goggles

A Pound of Cure

Problem

You added a file by mistake

Solution

RTFC

Problem

You removed a file by mistake

Solution

RTFC

Problem

Some file is cluttering up your status

Ignore it!

Problem

You want to ignore a file without updating all repositories

Use a global ignore file

But .DS_Store is still everywhere!

You could...

Problem

You wrote a bad commit message for the last commit

Solution

Amend it

Much better

Not just for commit messages

All changes in one commit

When using --amend, think locally

Problem

You want to clean up your local branches

Which branches can I delete?

Which branches should I keep?

Bonus: Which branches contain <commit>?

Use git branch

You want to know what changed in a commit

You pushed a bad commit

References

git-scm.com

pragprog.com/book/pg_git/pragmatic-guide-to-git

git-scm.com/book

(free)

pragprog.com/book/tsgit/pragmatic-version-control-using-git

help.github.com

cheat gem

cheat.errtheblog.com/

https://github.com/icefox/git-achievements

gitimmersion.com/

Q & A

Here on Friday afternoons

craig@8thlight.com

@demmer12

But `.DS_Store` is still everywhere!

When using `--amend`, think locally

Bonus: Which branches contain `<commit>`?

Use `git branch`

`cheat` gem