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Learning more about git

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If you are not familiar with git we suggest at least you learn the basics. The official and comprehensive man pages are included in the Git package itself. You can access to them with:

  git --help
  git <command> --help

Contents

Quick Git Setup

Setup SSH Keys

You can use git with https, but this requires to insert the username and password every time you need to push on the server (and to fetch or pull if the repository is private). Using ssh will save you some precious time. In order to use ssh you have to create an ssh key and add it to your profile on GitHub.

Your Identity

The first thing you should do is to set your user name and e-mail address.

 git config --global user.name "John Doe"
 git config --global user.email "john.doe@example.com"

Some Color

If you use git mostly from the command line, colors are very useful, you can enable them by running:

 git config --global color.pager true
 git config --global color.ui auto

Push behavior

We suggest you set upstream as the default push behavior:

 git config --global push.default upstream

Bash Prompt

Bash prompt can be tweaked to show you in which branch you are by using __git_ps1. For example you can replace your default prompt in your ~/.bashrc file with:

 if [ "$color_prompt" == "yes" ]; then
     PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\[\033[00;32m\]$(__git_ps1 " (%s)")\[\033[00m\]\$ '
 else
     PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w$(__git_ps1 " (%s)")\$ '
 fi

Migrating from SVN to Git preserving history

Simple projects

If the history of the project you want to migrate is simple (i.e. the project or its files were never moved around the repository), you can use git-svn to perform the migration.

The first step is to create a text file (e.g. authors.txt) that lists all of the users that would appear in your SVN repository and shows what their names would be for Git. The format is 'svn-username = Real Name <email address>', like so:

 mario-rossi = Mario Rossi <mario.rossi@iit.it>
 john-doe = John Doe <john@example.com>

Then, run the following commands:

 mkdir my_project_svn
 cd my_project_svn
 git svn init http://svn.blah.com/blah/trunk/ --no-metadata
 git config svn.authorsfile ../authors.txt
 git svn fetch

If you missed to list a user, the process gets stopped, but you can recover it by filling in the missing information and call "git svn fetch" iteratively.

Once the migration is completed, my_project_svn will still contain references to the original SVN repository; to get rid of them do:

 cd ..
 git clone my_project_svn my_project_git
 git remote remove origin

Finally, to publish my_project_git, create a brand new empty repository on your GitHub account and do:

 git remote add origin https://github.com/my-git-account/my_project_git
 git push origin master

Complicated projects

For projects that are more complicated you should use svn2git.

This includes the following cases:

  • The project folder was moved around.
  • Some files that are in your project were moved from outside your project folder.
  • You want to preserve svn branches or tags and convert them to git branches/tags.

svn2git is harder to use than git2svn, and it will require to download the whole robotcub repository revision database locally, and this will take time and disk space.

On the other side, once the database is downloaded the real migration is very fast because everything happens locally.

You can find some instructions and all the files used for the migration of some of the robotcub repositories: https://github.com/robotology-legacy/robotcub-ruleset

Recommended Tutorials

Try git in your browser:

  http://try.github.com/

LearnGitBranching - Web application designed to help beginners grasp the powerful concepts behind branching

  http://pcottle.github.io/learnGitBranching/

Git-it - Desktop application that teaches you how to use Git and GitHub on the command line

  https://github.com/jlord/git-it-electron

More

Git homepage

  http://git-scm.com/

A few more setup tricks can be found here:

  http://git-scm.com/book/en/Getting-Started-First-Time-Git-Setup

A very comprehensive source of documentation is this:

  http://git-scm.com/documentation

Git reference:

  http://gitref.org/

A Visual Git Reference:

  http://marklodato.github.io/visual-git-guide/index-en.html

If you are a subversion user, you might find useful this crash course for svn users. Please note that git and svn workflows are slightly different, this is only supposed to be used as reference.

  http://git.or.cz/course/svn.html

Git documentation wiki (contains several links):

  https://git.wiki.kernel.org/index.php/GitDocumentation

CMake Git resources (more links):

  http://www.cmake.org/Wiki/Git/Resources

A completely self-maintained and independent list of git tips and tricks made by Alessandro Roncone for his personal use (but useful nonetheless):

  http://alecive.github.io/blog/2015/07/08/GitHubTricks/

More links:

 http://git-scm.com/documentation/external-links

More tutorials can be found here:

  http://sixrevisions.com/resources/git-tutorials-beginners/

Interesting Readings

7 Git personalities, which one are you? (Suggestions to avoid common mistakes)

  https://about.gitlab.com/2015/01/27/7-git-personalities/
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