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Workflow
For information about how your workflow should go using git to keep track of changes to the main repository, see Git Workflow
Understanding Git
For developers transitioning from a Centralized Version Control System (CVCS) such as SVN to a Distributed Version Control System (DVCS) such as Git, the Pro Git book can be useful. A free version of the book can be read on-line or downloaded.
Another good resource is Think Like A Git, a site who's main page states "Git shouldn't be so hard to learn."
Finally, Git Best Practices is an excellent page with tons of information, overview and links to other good resources about best-practice usage of git.
Git Merge Strategies
Git has many "strategies" you can use while merging. Read the following carefully:
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MERGE STRATEGIES ---------------- The merge mechanism ('git-merge' and 'git-pull' commands) allows the backend 'merge strategies' to be chosen with `-s` option. Some strategies can also take their own options, which can be passed by giving `-X<option>` arguments to 'git-merge' and/or 'git-pull'. resolve:: This can only resolve two heads (i.e. the current branch and another branch you pulled from) using a 3-way merge algorithm. It tries to carefully detect criss-cross merge ambiguities and is considered generally safe and fast. recursive:: This can only resolve two heads using a 3-way merge algorithm. When there is more than one common ancestor that can be used for 3-way merge, it creates a merged tree of the common ancestors and uses that as the reference tree for the 3-way merge. This has been reported to result in fewer merge conflicts without causing mis-merges by tests done on actual merge commits taken from Linux 2.6 kernel development history. Additionally this can detect and handle merges involving renames. This is the default merge strategy when pulling or merging one branch. + The 'recursive' strategy can take the following options: ours;; This option forces conflicting hunks to be auto-resolved cleanly by favoring 'our' version. Changes from the other tree that do not conflict with our side are reflected to the merge result. + This should not be confused with the 'ours' merge strategy, which does not even look at what the other tree contains at all. It discards everything the other tree did, declaring 'our' history contains all that happened in it. theirs;; This is opposite of 'ours'. patience;; With this option, 'merge-recursive' spends a little extra time to avoid mismerges that sometimes occur due to unimportant matching lines (e.g., braces from distinct functions). Use this when the branches to be merged have diverged wildly. See also linkgit:git-diff[1] `--patience`. ignore-space-change;; ignore-all-space;; ignore-space-at-eol;; Treats lines with the indicated type of whitespace change as unchanged for the sake of a three-way merge. Whitespace changes mixed with other changes to a line are not ignored. See also linkgit:git-diff[1] `-b`, `-w`, and `--ignore-space-at-eol`. + * If 'their' version only introduces whitespace changes to a line, 'our' version is used; * If 'our' version introduces whitespace changes but 'their' version includes a substantial change, 'their' version is used; * Otherwise, the merge proceeds in the usual way. renormalize;; This runs a virtual check-out and check-in of all three stages of a file when resolving a three-way merge. This option is meant to be used when merging branches with different clean filters or end-of-line normalization rules. See "Merging branches with differing checkin/checkout attributes" in linkgit:gitattributes[5] for details. no-renormalize;; Disables the `renormalize` option. This overrides the `merge.renormalize` configuration variable. rename-threshold=<n>;; Controls the similarity threshold used for rename detection. See also linkgit:git-diff[1] `-M`. subtree[=<path>];; This option is a more advanced form of 'subtree' strategy, where the strategy makes a guess on how two trees must be shifted to match with each other when merging. Instead, the specified path is prefixed (or stripped from the beginning) to make the shape of two trees to match. octopus:: This resolves cases with more than two heads, but refuses to do a complex merge that needs manual resolution. It is primarily meant to be used for bundling topic branch heads together. This is the default merge strategy when pulling or merging more than one branch. ours:: This resolves any number of heads, but the resulting tree of the merge is always that of the current branch head, effectively ignoring all changes from all other branches. It is meant to be used to supersede old development history of side branches. Note that this is different from the -Xours option to the 'recursive' merge strategy. subtree:: This is a modified recursive strategy. When merging trees A and B, if B corresponds to a subtree of A, B is first adjusted to match the tree structure of A, instead of reading the trees at the same level. This adjustment is also done to the common ancestor tree. |
Git and Eclipse
The latest version of Eclipse (indigo) comes with a URL for installing EGit. The EGit eclipse plugin provides eclipse with git support. A good place to start is the User's guild: http://wiki.eclipse.org/EGit/User_Guide.
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This is a compilation of some potentially useful git commands and/or aliases
1) Command Line commit graph
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PITFALL - must be run against every new checkout of the repository. I'm not sure if this means when you swap branches, but I suspect it may.
3) Ignoring whitespace changes when a rebase fails
Sometimes when you go to do a rebase that should be simple, git fails and tells you that the entire file has changed. It may output something like this.
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M pom.xml
<stdin>:15: trailing whitespace.
<groupId>log4j</groupId>
<stdin>:16: trailing whitespace.
<artifactId>apache-log4j-extras</artifactId>
<stdin>:17: trailing whitespace.
<version>1.1</version>
<stdin>:18: trailing whitespace.
</dependency>
<stdin>:19: trailing whitespace.
warning: squelched 1 whitespace error
warning: 6 lines add whitespace errors. |
This indicates that there have been whitespace changes. Unless you're using python however, these probably aren't relevant and letting git sort them out will work fine. To do this, pass the --ignore-whitespace option to rebase.
Alternatively, you could run this command to make it so whitespace is automatically ignored unless you want it to be relevant:
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git config --global apply.ignorewhitespace change |
This is documented under the git-apply man page.
4) Recovering from terrible things happening to your git repository
Check out this blog post: http://www.programblings.com/2008/06/07/the-illustrated-guide-to-recovering-lost-commits-with-git/
Not really a git trick, but a github convenience. Repositories on github can have their default branch specified. This is useful to reduce drag and prevent worry, by making github automatically select the correct branch for a pull request to go into.
Simply go to your github repository's page and click the admin link (hint: you need admin privileges), right near the top of the page there's a setting called "Default Branch".