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diff --git a/third_party/git/Documentation/gitcore-tutorial.txt b/third_party/git/Documentation/gitcore-tutorial.txt deleted file mode 100644 index f880d21dfb..0000000000 --- a/third_party/git/Documentation/gitcore-tutorial.txt +++ /dev/null @@ -1,1660 +0,0 @@ -gitcore-tutorial(7) -=================== - -NAME ----- -gitcore-tutorial - A Git core tutorial for developers - -SYNOPSIS --------- -git * - -DESCRIPTION ------------ - -This tutorial explains how to use the "core" Git commands to set up and -work with a Git repository. - -If you just need to use Git as a revision control system you may prefer -to start with "A Tutorial Introduction to Git" (linkgit:gittutorial[7]) or -link:user-manual.html[the Git User Manual]. - -However, an understanding of these low-level tools can be helpful if -you want to understand Git's internals. - -The core Git is often called "plumbing", with the prettier user -interfaces on top of it called "porcelain". You may not want to use the -plumbing directly very often, but it can be good to know what the -plumbing does when the porcelain isn't flushing. - -Back when this document was originally written, many porcelain -commands were shell scripts. For simplicity, it still uses them as -examples to illustrate how plumbing is fit together to form the -porcelain commands. The source tree includes some of these scripts in -contrib/examples/ for reference. Although these are not implemented as -shell scripts anymore, the description of what the plumbing layer -commands do is still valid. - -[NOTE] -Deeper technical details are often marked as Notes, which you can -skip on your first reading. - - -Creating a Git repository -------------------------- - -Creating a new Git repository couldn't be easier: all Git repositories start -out empty, and the only thing you need to do is find yourself a -subdirectory that you want to use as a working tree - either an empty -one for a totally new project, or an existing working tree that you want -to import into Git. - -For our first example, we're going to start a totally new repository from -scratch, with no pre-existing files, and we'll call it 'git-tutorial'. -To start up, create a subdirectory for it, change into that -subdirectory, and initialize the Git infrastructure with 'git init': - ------------------------------------------------- -$ mkdir git-tutorial -$ cd git-tutorial -$ git init ------------------------------------------------- - -to which Git will reply - ----------------- -Initialized empty Git repository in .git/ ----------------- - -which is just Git's way of saying that you haven't been doing anything -strange, and that it will have created a local `.git` directory setup for -your new project. You will now have a `.git` directory, and you can -inspect that with 'ls'. For your new empty project, it should show you -three entries, among other things: - - - a file called `HEAD`, that has `ref: refs/heads/master` in it. - This is similar to a symbolic link and points at - `refs/heads/master` relative to the `HEAD` file. -+ -Don't worry about the fact that the file that the `HEAD` link points to -doesn't even exist yet -- you haven't created the commit that will -start your `HEAD` development branch yet. - - - a subdirectory called `objects`, which will contain all the - objects of your project. You should never have any real reason to - look at the objects directly, but you might want to know that these - objects are what contains all the real 'data' in your repository. - - - a subdirectory called `refs`, which contains references to objects. - -In particular, the `refs` subdirectory will contain two other -subdirectories, named `heads` and `tags` respectively. They do -exactly what their names imply: they contain references to any number -of different 'heads' of development (aka 'branches'), and to any -'tags' that you have created to name specific versions in your -repository. - -One note: the special `master` head is the default branch, which is -why the `.git/HEAD` file was created points to it even if it -doesn't yet exist. Basically, the `HEAD` link is supposed to always -point to the branch you are working on right now, and you always -start out expecting to work on the `master` branch. - -However, this is only a convention, and you can name your branches -anything you want, and don't have to ever even 'have' a `master` -branch. A number of the Git tools will assume that `.git/HEAD` is -valid, though. - -[NOTE] -An 'object' is identified by its 160-bit SHA-1 hash, aka 'object name', -and a reference to an object is always the 40-byte hex -representation of that SHA-1 name. The files in the `refs` -subdirectory are expected to contain these hex references -(usually with a final `\n` at the end), and you should thus -expect to see a number of 41-byte files containing these -references in these `refs` subdirectories when you actually start -populating your tree. - -[NOTE] -An advanced user may want to take a look at linkgit:gitrepository-layout[5] -after finishing this tutorial. - -You have now created your first Git repository. Of course, since it's -empty, that's not very useful, so let's start populating it with data. - - -Populating a Git repository ---------------------------- - -We'll keep this simple and stupid, so we'll start off with populating a -few trivial files just to get a feel for it. - -Start off with just creating any random files that you want to maintain -in your Git repository. We'll start off with a few bad examples, just to -get a feel for how this works: - ------------------------------------------------- -$ echo "Hello World" >hello -$ echo "Silly example" >example ------------------------------------------------- - -you have now created two files in your working tree (aka 'working directory'), -but to actually check in your hard work, you will have to go through two steps: - - - fill in the 'index' file (aka 'cache') with the information about your - working tree state. - - - commit that index file as an object. - -The first step is trivial: when you want to tell Git about any changes -to your working tree, you use the 'git update-index' program. That -program normally just takes a list of filenames you want to update, but -to avoid trivial mistakes, it refuses to add new entries to the index -(or remove existing ones) unless you explicitly tell it that you're -adding a new entry with the `--add` flag (or removing an entry with the -`--remove`) flag. - -So to populate the index with the two files you just created, you can do - ------------------------------------------------- -$ git update-index --add hello example ------------------------------------------------- - -and you have now told Git to track those two files. - -In fact, as you did that, if you now look into your object directory, -you'll notice that Git will have added two new objects to the object -database. If you did exactly the steps above, you should now be able to do - - ----------------- -$ ls .git/objects/??/* ----------------- - -and see two files: - ----------------- -.git/objects/55/7db03de997c86a4a028e1ebd3a1ceb225be238 -.git/objects/f2/4c74a2e500f5ee1332c86b94199f52b1d1d962 ----------------- - -which correspond with the objects with names of `557db...` and -`f24c7...` respectively. - -If you want to, you can use 'git cat-file' to look at those objects, but -you'll have to use the object name, not the filename of the object: - ----------------- -$ git cat-file -t 557db03de997c86a4a028e1ebd3a1ceb225be238 ----------------- - -where the `-t` tells 'git cat-file' to tell you what the "type" of the -object is. Git will tell you that you have a "blob" object (i.e., just a -regular file), and you can see the contents with - ----------------- -$ git cat-file blob 557db03 ----------------- - -which will print out "Hello World". The object `557db03` is nothing -more than the contents of your file `hello`. - -[NOTE] -Don't confuse that object with the file `hello` itself. The -object is literally just those specific *contents* of the file, and -however much you later change the contents in file `hello`, the object -we just looked at will never change. Objects are immutable. - -[NOTE] -The second example demonstrates that you can -abbreviate the object name to only the first several -hexadecimal digits in most places. - -Anyway, as we mentioned previously, you normally never actually take a -look at the objects themselves, and typing long 40-character hex -names is not something you'd normally want to do. The above digression -was just to show that 'git update-index' did something magical, and -actually saved away the contents of your files into the Git object -database. - -Updating the index did something else too: it created a `.git/index` -file. This is the index that describes your current working tree, and -something you should be very aware of. Again, you normally never worry -about the index file itself, but you should be aware of the fact that -you have not actually really "checked in" your files into Git so far, -you've only *told* Git about them. - -However, since Git knows about them, you can now start using some of the -most basic Git commands to manipulate the files or look at their status. - -In particular, let's not even check in the two files into Git yet, we'll -start off by adding another line to `hello` first: - ------------------------------------------------- -$ echo "It's a new day for git" >>hello ------------------------------------------------- - -and you can now, since you told Git about the previous state of `hello`, ask -Git what has changed in the tree compared to your old index, using the -'git diff-files' command: - ------------- -$ git diff-files ------------- - -Oops. That wasn't very readable. It just spit out its own internal -version of a 'diff', but that internal version really just tells you -that it has noticed that "hello" has been modified, and that the old object -contents it had have been replaced with something else. - -To make it readable, we can tell 'git diff-files' to output the -differences as a patch, using the `-p` flag: - ------------- -$ git diff-files -p -diff --git a/hello b/hello -index 557db03..263414f 100644 ---- a/hello -+++ b/hello -@@ -1 +1,2 @@ - Hello World -+It's a new day for git ------------- - -i.e. the diff of the change we caused by adding another line to `hello`. - -In other words, 'git diff-files' always shows us the difference between -what is recorded in the index, and what is currently in the working -tree. That's very useful. - -A common shorthand for `git diff-files -p` is to just write `git -diff`, which will do the same thing. - ------------- -$ git diff -diff --git a/hello b/hello -index 557db03..263414f 100644 ---- a/hello -+++ b/hello -@@ -1 +1,2 @@ - Hello World -+It's a new day for git ------------- - - -Committing Git state --------------------- - -Now, we want to go to the next stage in Git, which is to take the files -that Git knows about in the index, and commit them as a real tree. We do -that in two phases: creating a 'tree' object, and committing that 'tree' -object as a 'commit' object together with an explanation of what the -tree was all about, along with information of how we came to that state. - -Creating a tree object is trivial, and is done with 'git write-tree'. -There are no options or other input: `git write-tree` will take the -current index state, and write an object that describes that whole -index. In other words, we're now tying together all the different -filenames with their contents (and their permissions), and we're -creating the equivalent of a Git "directory" object: - ------------------------------------------------- -$ git write-tree ------------------------------------------------- - -and this will just output the name of the resulting tree, in this case -(if you have done exactly as I've described) it should be - ----------------- -8988da15d077d4829fc51d8544c097def6644dbb ----------------- - -which is another incomprehensible object name. Again, if you want to, -you can use `git cat-file -t 8988d...` to see that this time the object -is not a "blob" object, but a "tree" object (you can also use -`git cat-file` to actually output the raw object contents, but you'll see -mainly a binary mess, so that's less interesting). - -However -- normally you'd never use 'git write-tree' on its own, because -normally you always commit a tree into a commit object using the -'git commit-tree' command. In fact, it's easier to not actually use -'git write-tree' on its own at all, but to just pass its result in as an -argument to 'git commit-tree'. - -'git commit-tree' normally takes several arguments -- it wants to know -what the 'parent' of a commit was, but since this is the first commit -ever in this new repository, and it has no parents, we only need to pass in -the object name of the tree. However, 'git commit-tree' also wants to get a -commit message on its standard input, and it will write out the resulting -object name for the commit to its standard output. - -And this is where we create the `.git/refs/heads/master` file -which is pointed at by `HEAD`. This file is supposed to contain -the reference to the top-of-tree of the master branch, and since -that's exactly what 'git commit-tree' spits out, we can do this -all with a sequence of simple shell commands: - ------------------------------------------------- -$ tree=$(git write-tree) -$ commit=$(echo 'Initial commit' | git commit-tree $tree) -$ git update-ref HEAD $commit ------------------------------------------------- - -In this case this creates a totally new commit that is not related to -anything else. Normally you do this only *once* for a project ever, and -all later commits will be parented on top of an earlier commit. - -Again, normally you'd never actually do this by hand. There is a -helpful script called `git commit` that will do all of this for you. So -you could have just written `git commit` -instead, and it would have done the above magic scripting for you. - - -Making a change ---------------- - -Remember how we did the 'git update-index' on file `hello` and then we -changed `hello` afterward, and could compare the new state of `hello` with the -state we saved in the index file? - -Further, remember how I said that 'git write-tree' writes the contents -of the *index* file to the tree, and thus what we just committed was in -fact the *original* contents of the file `hello`, not the new ones. We did -that on purpose, to show the difference between the index state, and the -state in the working tree, and how they don't have to match, even -when we commit things. - -As before, if we do `git diff-files -p` in our git-tutorial project, -we'll still see the same difference we saw last time: the index file -hasn't changed by the act of committing anything. However, now that we -have committed something, we can also learn to use a new command: -'git diff-index'. - -Unlike 'git diff-files', which showed the difference between the index -file and the working tree, 'git diff-index' shows the differences -between a committed *tree* and either the index file or the working -tree. In other words, 'git diff-index' wants a tree to be diffed -against, and before we did the commit, we couldn't do that, because we -didn't have anything to diff against. - -But now we can do - ----------------- -$ git diff-index -p HEAD ----------------- - -(where `-p` has the same meaning as it did in 'git diff-files'), and it -will show us the same difference, but for a totally different reason. -Now we're comparing the working tree not against the index file, -but against the tree we just wrote. It just so happens that those two -are obviously the same, so we get the same result. - -Again, because this is a common operation, you can also just shorthand -it with - ----------------- -$ git diff HEAD ----------------- - -which ends up doing the above for you. - -In other words, 'git diff-index' normally compares a tree against the -working tree, but when given the `--cached` flag, it is told to -instead compare against just the index cache contents, and ignore the -current working tree state entirely. Since we just wrote the index -file to HEAD, doing `git diff-index --cached -p HEAD` should thus return -an empty set of differences, and that's exactly what it does. - -[NOTE] -================ -'git diff-index' really always uses the index for its -comparisons, and saying that it compares a tree against the working -tree is thus not strictly accurate. In particular, the list of -files to compare (the "meta-data") *always* comes from the index file, -regardless of whether the `--cached` flag is used or not. The `--cached` -flag really only determines whether the file *contents* to be compared -come from the working tree or not. - -This is not hard to understand, as soon as you realize that Git simply -never knows (or cares) about files that it is not told about -explicitly. Git will never go *looking* for files to compare, it -expects you to tell it what the files are, and that's what the index -is there for. -================ - -However, our next step is to commit the *change* we did, and again, to -understand what's going on, keep in mind the difference between "working -tree contents", "index file" and "committed tree". We have changes -in the working tree that we want to commit, and we always have to -work through the index file, so the first thing we need to do is to -update the index cache: - ------------------------------------------------- -$ git update-index hello ------------------------------------------------- - -(note how we didn't need the `--add` flag this time, since Git knew -about the file already). - -Note what happens to the different 'git diff-{asterisk}' versions here. -After we've updated `hello` in the index, `git diff-files -p` now shows no -differences, but `git diff-index -p HEAD` still *does* show that the -current state is different from the state we committed. In fact, now -'git diff-index' shows the same difference whether we use the `--cached` -flag or not, since now the index is coherent with the working tree. - -Now, since we've updated `hello` in the index, we can commit the new -version. We could do it by writing the tree by hand again, and -committing the tree (this time we'd have to use the `-p HEAD` flag to -tell commit that the HEAD was the *parent* of the new commit, and that -this wasn't an initial commit any more), but you've done that once -already, so let's just use the helpful script this time: - ------------------------------------------------- -$ git commit ------------------------------------------------- - -which starts an editor for you to write the commit message and tells you -a bit about what you have done. - -Write whatever message you want, and all the lines that start with '#' -will be pruned out, and the rest will be used as the commit message for -the change. If you decide you don't want to commit anything after all at -this point (you can continue to edit things and update the index), you -can just leave an empty message. Otherwise `git commit` will commit -the change for you. - -You've now made your first real Git commit. And if you're interested in -looking at what `git commit` really does, feel free to investigate: -it's a few very simple shell scripts to generate the helpful (?) commit -message headers, and a few one-liners that actually do the -commit itself ('git commit'). - - -Inspecting Changes ------------------- - -While creating changes is useful, it's even more useful if you can tell -later what changed. The most useful command for this is another of the -'diff' family, namely 'git diff-tree'. - -'git diff-tree' can be given two arbitrary trees, and it will tell you the -differences between them. Perhaps even more commonly, though, you can -give it just a single commit object, and it will figure out the parent -of that commit itself, and show the difference directly. Thus, to get -the same diff that we've already seen several times, we can now do - ----------------- -$ git diff-tree -p HEAD ----------------- - -(again, `-p` means to show the difference as a human-readable patch), -and it will show what the last commit (in `HEAD`) actually changed. - -[NOTE] -============ -Here is an ASCII art by Jon Loeliger that illustrates how -various 'diff-{asterisk}' commands compare things. - - diff-tree - +----+ - | | - | | - V V - +-----------+ - | Object DB | - | Backing | - | Store | - +-----------+ - ^ ^ - | | - | | diff-index --cached - | | - diff-index | V - | +-----------+ - | | Index | - | | "cache" | - | +-----------+ - | ^ - | | - | | diff-files - | | - V V - +-----------+ - | Working | - | Directory | - +-----------+ -============ - -More interestingly, you can also give 'git diff-tree' the `--pretty` flag, -which tells it to also show the commit message and author and date of the -commit, and you can tell it to show a whole series of diffs. -Alternatively, you can tell it to be "silent", and not show the diffs at -all, but just show the actual commit message. - -In fact, together with the 'git rev-list' program (which generates a -list of revisions), 'git diff-tree' ends up being a veritable fount of -changes. You can emulate `git log`, `git log -p`, etc. with a trivial -script that pipes the output of `git rev-list` to `git diff-tree --stdin`, -which was exactly how early versions of `git log` were implemented. - - -Tagging a version ------------------ - -In Git, there are two kinds of tags, a "light" one, and an "annotated tag". - -A "light" tag is technically nothing more than a branch, except we put -it in the `.git/refs/tags/` subdirectory instead of calling it a `head`. -So the simplest form of tag involves nothing more than - ------------------------------------------------- -$ git tag my-first-tag ------------------------------------------------- - -which just writes the current `HEAD` into the `.git/refs/tags/my-first-tag` -file, after which point you can then use this symbolic name for that -particular state. You can, for example, do - ----------------- -$ git diff my-first-tag ----------------- - -to diff your current state against that tag which at this point will -obviously be an empty diff, but if you continue to develop and commit -stuff, you can use your tag as an "anchor-point" to see what has changed -since you tagged it. - -An "annotated tag" is actually a real Git object, and contains not only a -pointer to the state you want to tag, but also a small tag name and -message, along with optionally a PGP signature that says that yes, -you really did -that tag. You create these annotated tags with either the `-a` or -`-s` flag to 'git tag': - ----------------- -$ git tag -s <tagname> ----------------- - -which will sign the current `HEAD` (but you can also give it another -argument that specifies the thing to tag, e.g., you could have tagged the -current `mybranch` point by using `git tag <tagname> mybranch`). - -You normally only do signed tags for major releases or things -like that, while the light-weight tags are useful for any marking you -want to do -- any time you decide that you want to remember a certain -point, just create a private tag for it, and you have a nice symbolic -name for the state at that point. - - -Copying repositories --------------------- - -Git repositories are normally totally self-sufficient and relocatable. -Unlike CVS, for example, there is no separate notion of -"repository" and "working tree". A Git repository normally *is* the -working tree, with the local Git information hidden in the `.git` -subdirectory. There is nothing else. What you see is what you got. - -[NOTE] -You can tell Git to split the Git internal information from -the directory that it tracks, but we'll ignore that for now: it's not -how normal projects work, and it's really only meant for special uses. -So the mental model of "the Git information is always tied directly to -the working tree that it describes" may not be technically 100% -accurate, but it's a good model for all normal use. - -This has two implications: - - - if you grow bored with the tutorial repository you created (or you've - made a mistake and want to start all over), you can just do simple -+ ----------------- -$ rm -rf git-tutorial ----------------- -+ -and it will be gone. There's no external repository, and there's no -history outside the project you created. - - - if you want to move or duplicate a Git repository, you can do so. There - is 'git clone' command, but if all you want to do is just to - create a copy of your repository (with all the full history that - went along with it), you can do so with a regular - `cp -a git-tutorial new-git-tutorial`. -+ -Note that when you've moved or copied a Git repository, your Git index -file (which caches various information, notably some of the "stat" -information for the files involved) will likely need to be refreshed. -So after you do a `cp -a` to create a new copy, you'll want to do -+ ----------------- -$ git update-index --refresh ----------------- -+ -in the new repository to make sure that the index file is up to date. - -Note that the second point is true even across machines. You can -duplicate a remote Git repository with *any* regular copy mechanism, be it -'scp', 'rsync' or 'wget'. - -When copying a remote repository, you'll want to at a minimum update the -index cache when you do this, and especially with other peoples' -repositories you often want to make sure that the index cache is in some -known state (you don't know *what* they've done and not yet checked in), -so usually you'll precede the 'git update-index' with a - ----------------- -$ git read-tree --reset HEAD -$ git update-index --refresh ----------------- - -which will force a total index re-build from the tree pointed to by `HEAD`. -It resets the index contents to `HEAD`, and then the 'git update-index' -makes sure to match up all index entries with the checked-out files. -If the original repository had uncommitted changes in its -working tree, `git update-index --refresh` notices them and -tells you they need to be updated. - -The above can also be written as simply - ----------------- -$ git reset ----------------- - -and in fact a lot of the common Git command combinations can be scripted -with the `git xyz` interfaces. You can learn things by just looking -at what the various git scripts do. For example, `git reset` used to be -the above two lines implemented in 'git reset', but some things like -'git status' and 'git commit' are slightly more complex scripts around -the basic Git commands. - -Many (most?) public remote repositories will not contain any of -the checked out files or even an index file, and will *only* contain the -actual core Git files. Such a repository usually doesn't even have the -`.git` subdirectory, but has all the Git files directly in the -repository. - -To create your own local live copy of such a "raw" Git repository, you'd -first create your own subdirectory for the project, and then copy the -raw repository contents into the `.git` directory. For example, to -create your own copy of the Git repository, you'd do the following - ----------------- -$ mkdir my-git -$ cd my-git -$ rsync -rL rsync://rsync.kernel.org/pub/scm/git/git.git/ .git ----------------- - -followed by - ----------------- -$ git read-tree HEAD ----------------- - -to populate the index. However, now you have populated the index, and -you have all the Git internal files, but you will notice that you don't -actually have any of the working tree files to work on. To get -those, you'd check them out with - ----------------- -$ git checkout-index -u -a ----------------- - -where the `-u` flag means that you want the checkout to keep the index -up to date (so that you don't have to refresh it afterward), and the -`-a` flag means "check out all files" (if you have a stale copy or an -older version of a checked out tree you may also need to add the `-f` -flag first, to tell 'git checkout-index' to *force* overwriting of any old -files). - -Again, this can all be simplified with - ----------------- -$ git clone git://git.kernel.org/pub/scm/git/git.git/ my-git -$ cd my-git -$ git checkout ----------------- - -which will end up doing all of the above for you. - -You have now successfully copied somebody else's (mine) remote -repository, and checked it out. - - -Creating a new branch ---------------------- - -Branches in Git are really nothing more than pointers into the Git -object database from within the `.git/refs/` subdirectory, and as we -already discussed, the `HEAD` branch is nothing but a symlink to one of -these object pointers. - -You can at any time create a new branch by just picking an arbitrary -point in the project history, and just writing the SHA-1 name of that -object into a file under `.git/refs/heads/`. You can use any filename you -want (and indeed, subdirectories), but the convention is that the -"normal" branch is called `master`. That's just a convention, though, -and nothing enforces it. - -To show that as an example, let's go back to the git-tutorial repository we -used earlier, and create a branch in it. You do that by simply just -saying that you want to check out a new branch: - ------------- -$ git switch -c mybranch ------------- - -will create a new branch based at the current `HEAD` position, and switch -to it. - -[NOTE] -================================================ -If you make the decision to start your new branch at some -other point in the history than the current `HEAD`, you can do so by -just telling 'git checkout' what the base of the checkout would be. -In other words, if you have an earlier tag or branch, you'd just do - ------------- -$ git switch -c mybranch earlier-commit ------------- - -and it would create the new branch `mybranch` at the earlier commit, -and check out the state at that time. -================================================ - -You can always just jump back to your original `master` branch by doing - ------------- -$ git switch master ------------- - -(or any other branch-name, for that matter) and if you forget which -branch you happen to be on, a simple - ------------- -$ cat .git/HEAD ------------- - -will tell you where it's pointing. To get the list of branches -you have, you can say - ------------- -$ git branch ------------- - -which used to be nothing more than a simple script around `ls .git/refs/heads`. -There will be an asterisk in front of the branch you are currently on. - -Sometimes you may wish to create a new branch _without_ actually -checking it out and switching to it. If so, just use the command - ------------- -$ git branch <branchname> [startingpoint] ------------- - -which will simply _create_ the branch, but will not do anything further. -You can then later -- once you decide that you want to actually develop -on that branch -- switch to that branch with a regular 'git switch' -with the branchname as the argument. - - -Merging two branches --------------------- - -One of the ideas of having a branch is that you do some (possibly -experimental) work in it, and eventually merge it back to the main -branch. So assuming you created the above `mybranch` that started out -being the same as the original `master` branch, let's make sure we're in -that branch, and do some work there. - ------------------------------------------------- -$ git switch mybranch -$ echo "Work, work, work" >>hello -$ git commit -m "Some work." -i hello ------------------------------------------------- - -Here, we just added another line to `hello`, and we used a shorthand for -doing both `git update-index hello` and `git commit` by just giving the -filename directly to `git commit`, with an `-i` flag (it tells -Git to 'include' that file in addition to what you have done to -the index file so far when making the commit). The `-m` flag is to give the -commit log message from the command line. - -Now, to make it a bit more interesting, let's assume that somebody else -does some work in the original branch, and simulate that by going back -to the master branch, and editing the same file differently there: - ------------- -$ git switch master ------------- - -Here, take a moment to look at the contents of `hello`, and notice how they -don't contain the work we just did in `mybranch` -- because that work -hasn't happened in the `master` branch at all. Then do - ------------- -$ echo "Play, play, play" >>hello -$ echo "Lots of fun" >>example -$ git commit -m "Some fun." -i hello example ------------- - -since the master branch is obviously in a much better mood. - -Now, you've got two branches, and you decide that you want to merge the -work done. Before we do that, let's introduce a cool graphical tool that -helps you view what's going on: - ----------------- -$ gitk --all ----------------- - -will show you graphically both of your branches (that's what the `--all` -means: normally it will just show you your current `HEAD`) and their -histories. You can also see exactly how they came to be from a common -source. - -Anyway, let's exit 'gitk' (`^Q` or the File menu), and decide that we want -to merge the work we did on the `mybranch` branch into the `master` -branch (which is currently our `HEAD` too). To do that, there's a nice -script called 'git merge', which wants to know which branches you want -to resolve and what the merge is all about: - ------------- -$ git merge -m "Merge work in mybranch" mybranch ------------- - -where the first argument is going to be used as the commit message if -the merge can be resolved automatically. - -Now, in this case we've intentionally created a situation where the -merge will need to be fixed up by hand, though, so Git will do as much -of it as it can automatically (which in this case is just merge the `example` -file, which had no differences in the `mybranch` branch), and say: - ----------------- - Auto-merging hello - CONFLICT (content): Merge conflict in hello - Automatic merge failed; fix conflicts and then commit the result. ----------------- - -It tells you that it did an "Automatic merge", which -failed due to conflicts in `hello`. - -Not to worry. It left the (trivial) conflict in `hello` in the same form you -should already be well used to if you've ever used CVS, so let's just -open `hello` in our editor (whatever that may be), and fix it up somehow. -I'd suggest just making it so that `hello` contains all four lines: - ------------- -Hello World -It's a new day for git -Play, play, play -Work, work, work ------------- - -and once you're happy with your manual merge, just do a - ------------- -$ git commit -i hello ------------- - -which will very loudly warn you that you're now committing a merge -(which is correct, so never mind), and you can write a small merge -message about your adventures in 'git merge'-land. - -After you're done, start up `gitk --all` to see graphically what the -history looks like. Notice that `mybranch` still exists, and you can -switch to it, and continue to work with it if you want to. The -`mybranch` branch will not contain the merge, but next time you merge it -from the `master` branch, Git will know how you merged it, so you'll not -have to do _that_ merge again. - -Another useful tool, especially if you do not always work in X-Window -environment, is `git show-branch`. - ------------------------------------------------- -$ git show-branch --topo-order --more=1 master mybranch -* [master] Merge work in mybranch - ! [mybranch] Some work. --- -- [master] Merge work in mybranch -*+ [mybranch] Some work. -* [master^] Some fun. ------------------------------------------------- - -The first two lines indicate that it is showing the two branches -with the titles of their top-of-the-tree commits, you are currently on -`master` branch (notice the asterisk `*` character), and the first -column for the later output lines is used to show commits contained in the -`master` branch, and the second column for the `mybranch` -branch. Three commits are shown along with their titles. -All of them have non blank characters in the first column (`*` -shows an ordinary commit on the current branch, `-` is a merge commit), which -means they are now part of the `master` branch. Only the "Some -work" commit has the plus `+` character in the second column, -because `mybranch` has not been merged to incorporate these -commits from the master branch. The string inside brackets -before the commit log message is a short name you can use to -name the commit. In the above example, 'master' and 'mybranch' -are branch heads. 'master^' is the first parent of 'master' -branch head. Please see linkgit:gitrevisions[7] if you want to -see more complex cases. - -[NOTE] -Without the '--more=1' option, 'git show-branch' would not output the -'[master^]' commit, as '[mybranch]' commit is a common ancestor of -both 'master' and 'mybranch' tips. Please see linkgit:git-show-branch[1] -for details. - -[NOTE] -If there were more commits on the 'master' branch after the merge, the -merge commit itself would not be shown by 'git show-branch' by -default. You would need to provide `--sparse` option to make the -merge commit visible in this case. - -Now, let's pretend you are the one who did all the work in -`mybranch`, and the fruit of your hard work has finally been merged -to the `master` branch. Let's go back to `mybranch`, and run -'git merge' to get the "upstream changes" back to your branch. - ------------- -$ git switch mybranch -$ git merge -m "Merge upstream changes." master ------------- - -This outputs something like this (the actual commit object names -would be different) - ----------------- -Updating from ae3a2da... to a80b4aa.... -Fast-forward (no commit created; -m option ignored) - example | 1 + - hello | 1 + - 2 files changed, 2 insertions(+) ----------------- - -Because your branch did not contain anything more than what had -already been merged into the `master` branch, the merge operation did -not actually do a merge. Instead, it just updated the top of -the tree of your branch to that of the `master` branch. This is -often called 'fast-forward' merge. - -You can run `gitk --all` again to see how the commit ancestry -looks like, or run 'show-branch', which tells you this. - ------------------------------------------------- -$ git show-branch master mybranch -! [master] Merge work in mybranch - * [mybranch] Merge work in mybranch --- --- [master] Merge work in mybranch ------------------------------------------------- - - -Merging external work ---------------------- - -It's usually much more common that you merge with somebody else than -merging with your own branches, so it's worth pointing out that Git -makes that very easy too, and in fact, it's not that different from -doing a 'git merge'. In fact, a remote merge ends up being nothing -more than "fetch the work from a remote repository into a temporary tag" -followed by a 'git merge'. - -Fetching from a remote repository is done by, unsurprisingly, -'git fetch': - ----------------- -$ git fetch <remote-repository> ----------------- - -One of the following transports can be used to name the -repository to download from: - -SSH:: - `remote.machine:/path/to/repo.git/` or -+ -`ssh://remote.machine/path/to/repo.git/` -+ -This transport can be used for both uploading and downloading, -and requires you to have a log-in privilege over `ssh` to the -remote machine. It finds out the set of objects the other side -lacks by exchanging the head commits both ends have and -transfers (close to) minimum set of objects. It is by far the -most efficient way to exchange Git objects between repositories. - -Local directory:: - `/path/to/repo.git/` -+ -This transport is the same as SSH transport but uses 'sh' to run -both ends on the local machine instead of running other end on -the remote machine via 'ssh'. - -Git Native:: - `git://remote.machine/path/to/repo.git/` -+ -This transport was designed for anonymous downloading. Like SSH -transport, it finds out the set of objects the downstream side -lacks and transfers (close to) minimum set of objects. - -HTTP(S):: - `http://remote.machine/path/to/repo.git/` -+ -Downloader from http and https URL -first obtains the topmost commit object name from the remote site -by looking at the specified refname under `repo.git/refs/` directory, -and then tries to obtain the -commit object by downloading from `repo.git/objects/xx/xxx...` -using the object name of that commit object. Then it reads the -commit object to find out its parent commits and the associate -tree object; it repeats this process until it gets all the -necessary objects. Because of this behavior, they are -sometimes also called 'commit walkers'. -+ -The 'commit walkers' are sometimes also called 'dumb -transports', because they do not require any Git aware smart -server like Git Native transport does. Any stock HTTP server -that does not even support directory index would suffice. But -you must prepare your repository with 'git update-server-info' -to help dumb transport downloaders. - -Once you fetch from the remote repository, you `merge` that -with your current branch. - -However -- it's such a common thing to `fetch` and then -immediately `merge`, that it's called `git pull`, and you can -simply do - ----------------- -$ git pull <remote-repository> ----------------- - -and optionally give a branch-name for the remote end as a second -argument. - -[NOTE] -You could do without using any branches at all, by -keeping as many local repositories as you would like to have -branches, and merging between them with 'git pull', just like -you merge between branches. The advantage of this approach is -that it lets you keep a set of files for each `branch` checked -out and you may find it easier to switch back and forth if you -juggle multiple lines of development simultaneously. Of -course, you will pay the price of more disk usage to hold -multiple working trees, but disk space is cheap these days. - -It is likely that you will be pulling from the same remote -repository from time to time. As a short hand, you can store -the remote repository URL in the local repository's config file -like this: - ------------------------------------------------- -$ git config remote.linus.url http://www.kernel.org/pub/scm/git/git.git/ ------------------------------------------------- - -and use the "linus" keyword with 'git pull' instead of the full URL. - -Examples. - -. `git pull linus` -. `git pull linus tag v0.99.1` - -the above are equivalent to: - -. `git pull http://www.kernel.org/pub/scm/git/git.git/ HEAD` -. `git pull http://www.kernel.org/pub/scm/git/git.git/ tag v0.99.1` - - -How does the merge work? ------------------------- - -We said this tutorial shows what plumbing does to help you cope -with the porcelain that isn't flushing, but we so far did not -talk about how the merge really works. If you are following -this tutorial the first time, I'd suggest to skip to "Publishing -your work" section and come back here later. - -OK, still with me? To give us an example to look at, let's go -back to the earlier repository with "hello" and "example" file, -and bring ourselves back to the pre-merge state: - ------------- -$ git show-branch --more=2 master mybranch -! [master] Merge work in mybranch - * [mybranch] Merge work in mybranch --- --- [master] Merge work in mybranch -+* [master^2] Some work. -+* [master^] Some fun. ------------- - -Remember, before running 'git merge', our `master` head was at -"Some fun." commit, while our `mybranch` head was at "Some -work." commit. - ------------- -$ git switch -C mybranch master^2 -$ git switch master -$ git reset --hard master^ ------------- - -After rewinding, the commit structure should look like this: - ------------- -$ git show-branch -* [master] Some fun. - ! [mybranch] Some work. --- -* [master] Some fun. - + [mybranch] Some work. -*+ [master^] Initial commit ------------- - -Now we are ready to experiment with the merge by hand. - -`git merge` command, when merging two branches, uses 3-way merge -algorithm. First, it finds the common ancestor between them. -The command it uses is 'git merge-base': - ------------- -$ mb=$(git merge-base HEAD mybranch) ------------- - -The command writes the commit object name of the common ancestor -to the standard output, so we captured its output to a variable, -because we will be using it in the next step. By the way, the common -ancestor commit is the "Initial commit" commit in this case. You can -tell it by: - ------------- -$ git name-rev --name-only --tags $mb -my-first-tag ------------- - -After finding out a common ancestor commit, the second step is -this: - ------------- -$ git read-tree -m -u $mb HEAD mybranch ------------- - -This is the same 'git read-tree' command we have already seen, -but it takes three trees, unlike previous examples. This reads -the contents of each tree into different 'stage' in the index -file (the first tree goes to stage 1, the second to stage 2, -etc.). After reading three trees into three stages, the paths -that are the same in all three stages are 'collapsed' into stage -0. Also paths that are the same in two of three stages are -collapsed into stage 0, taking the SHA-1 from either stage 2 or -stage 3, whichever is different from stage 1 (i.e. only one side -changed from the common ancestor). - -After 'collapsing' operation, paths that are different in three -trees are left in non-zero stages. At this point, you can -inspect the index file with this command: - ------------- -$ git ls-files --stage -100644 7f8b141b65fdcee47321e399a2598a235a032422 0 example -100644 557db03de997c86a4a028e1ebd3a1ceb225be238 1 hello -100644 ba42a2a96e3027f3333e13ede4ccf4498c3ae942 2 hello -100644 cc44c73eb783565da5831b4d820c962954019b69 3 hello ------------- - -In our example of only two files, we did not have unchanged -files so only 'example' resulted in collapsing. But in real-life -large projects, when only a small number of files change in one commit, -this 'collapsing' tends to trivially merge most of the paths -fairly quickly, leaving only a handful of real changes in non-zero -stages. - -To look at only non-zero stages, use `--unmerged` flag: - ------------- -$ git ls-files --unmerged -100644 557db03de997c86a4a028e1ebd3a1ceb225be238 1 hello -100644 ba42a2a96e3027f3333e13ede4ccf4498c3ae942 2 hello -100644 cc44c73eb783565da5831b4d820c962954019b69 3 hello ------------- - -The next step of merging is to merge these three versions of the -file, using 3-way merge. This is done by giving -'git merge-one-file' command as one of the arguments to -'git merge-index' command: - ------------- -$ git merge-index git-merge-one-file hello -Auto-merging hello -ERROR: Merge conflict in hello -fatal: merge program failed ------------- - -'git merge-one-file' script is called with parameters to -describe those three versions, and is responsible to leave the -merge results in the working tree. -It is a fairly straightforward shell script, and -eventually calls 'merge' program from RCS suite to perform a -file-level 3-way merge. In this case, 'merge' detects -conflicts, and the merge result with conflict marks is left in -the working tree.. This can be seen if you run `ls-files ---stage` again at this point: - ------------- -$ git ls-files --stage -100644 7f8b141b65fdcee47321e399a2598a235a032422 0 example -100644 557db03de997c86a4a028e1ebd3a1ceb225be238 1 hello -100644 ba42a2a96e3027f3333e13ede4ccf4498c3ae942 2 hello -100644 cc44c73eb783565da5831b4d820c962954019b69 3 hello ------------- - -This is the state of the index file and the working file after -'git merge' returns control back to you, leaving the conflicting -merge for you to resolve. Notice that the path `hello` is still -unmerged, and what you see with 'git diff' at this point is -differences since stage 2 (i.e. your version). - - -Publishing your work --------------------- - -So, we can use somebody else's work from a remote repository, but -how can *you* prepare a repository to let other people pull from -it? - -You do your real work in your working tree that has your -primary repository hanging under it as its `.git` subdirectory. -You *could* make that repository accessible remotely and ask -people to pull from it, but in practice that is not the way -things are usually done. A recommended way is to have a public -repository, make it reachable by other people, and when the -changes you made in your primary working tree are in good shape, -update the public repository from it. This is often called -'pushing'. - -[NOTE] -This public repository could further be mirrored, and that is -how Git repositories at `kernel.org` are managed. - -Publishing the changes from your local (private) repository to -your remote (public) repository requires a write privilege on -the remote machine. You need to have an SSH account there to -run a single command, 'git-receive-pack'. - -First, you need to create an empty repository on the remote -machine that will house your public repository. This empty -repository will be populated and be kept up to date by pushing -into it later. Obviously, this repository creation needs to be -done only once. - -[NOTE] -'git push' uses a pair of commands, -'git send-pack' on your local machine, and 'git-receive-pack' -on the remote machine. The communication between the two over -the network internally uses an SSH connection. - -Your private repository's Git directory is usually `.git`, but -your public repository is often named after the project name, -i.e. `<project>.git`. Let's create such a public repository for -project `my-git`. After logging into the remote machine, create -an empty directory: - ------------- -$ mkdir my-git.git ------------- - -Then, make that directory into a Git repository by running -'git init', but this time, since its name is not the usual -`.git`, we do things slightly differently: - ------------- -$ GIT_DIR=my-git.git git init ------------- - -Make sure this directory is available for others you want your -changes to be pulled via the transport of your choice. Also -you need to make sure that you have the 'git-receive-pack' -program on the `$PATH`. - -[NOTE] -Many installations of sshd do not invoke your shell as the login -shell when you directly run programs; what this means is that if -your login shell is 'bash', only `.bashrc` is read and not -`.bash_profile`. As a workaround, make sure `.bashrc` sets up -`$PATH` so that you can run 'git-receive-pack' program. - -[NOTE] -If you plan to publish this repository to be accessed over http, -you should do `mv my-git.git/hooks/post-update.sample -my-git.git/hooks/post-update` at this point. -This makes sure that every time you push into this -repository, `git update-server-info` is run. - -Your "public repository" is now ready to accept your changes. -Come back to the machine you have your private repository. From -there, run this command: - ------------- -$ git push <public-host>:/path/to/my-git.git master ------------- - -This synchronizes your public repository to match the named -branch head (i.e. `master` in this case) and objects reachable -from them in your current repository. - -As a real example, this is how I update my public Git -repository. Kernel.org mirror network takes care of the -propagation to other publicly visible machines: - ------------- -$ git push master.kernel.org:/pub/scm/git/git.git/ ------------- - - -Packing your repository ------------------------ - -Earlier, we saw that one file under `.git/objects/??/` directory -is stored for each Git object you create. This representation -is efficient to create atomically and safely, but -not so convenient to transport over the network. Since Git objects are -immutable once they are created, there is a way to optimize the -storage by "packing them together". The command - ------------- -$ git repack ------------- - -will do it for you. If you followed the tutorial examples, you -would have accumulated about 17 objects in `.git/objects/??/` -directories by now. 'git repack' tells you how many objects it -packed, and stores the packed file in the `.git/objects/pack` -directory. - -[NOTE] -You will see two files, `pack-*.pack` and `pack-*.idx`, -in `.git/objects/pack` directory. They are closely related to -each other, and if you ever copy them by hand to a different -repository for whatever reason, you should make sure you copy -them together. The former holds all the data from the objects -in the pack, and the latter holds the index for random -access. - -If you are paranoid, running 'git verify-pack' command would -detect if you have a corrupt pack, but do not worry too much. -Our programs are always perfect ;-). - -Once you have packed objects, you do not need to leave the -unpacked objects that are contained in the pack file anymore. - ------------- -$ git prune-packed ------------- - -would remove them for you. - -You can try running `find .git/objects -type f` before and after -you run `git prune-packed` if you are curious. Also `git -count-objects` would tell you how many unpacked objects are in -your repository and how much space they are consuming. - -[NOTE] -`git pull` is slightly cumbersome for HTTP transport, as a -packed repository may contain relatively few objects in a -relatively large pack. If you expect many HTTP pulls from your -public repository you might want to repack & prune often, or -never. - -If you run `git repack` again at this point, it will say -"Nothing new to pack.". Once you continue your development and -accumulate the changes, running `git repack` again will create a -new pack, that contains objects created since you packed your -repository the last time. We recommend that you pack your project -soon after the initial import (unless you are starting your -project from scratch), and then run `git repack` every once in a -while, depending on how active your project is. - -When a repository is synchronized via `git push` and `git pull` -objects packed in the source repository are usually stored -unpacked in the destination. -While this allows you to use different packing strategies on -both ends, it also means you may need to repack both -repositories every once in a while. - - -Working with Others -------------------- - -Although Git is a truly distributed system, it is often -convenient to organize your project with an informal hierarchy -of developers. Linux kernel development is run this way. There -is a nice illustration (page 17, "Merges to Mainline") in -https://web.archive.org/web/20120915203609/http://www.xenotime.net/linux/mentor/linux-mentoring-2006.pdf[Randy Dunlap's presentation]. - -It should be stressed that this hierarchy is purely *informal*. -There is nothing fundamental in Git that enforces the "chain of -patch flow" this hierarchy implies. You do not have to pull -from only one remote repository. - -A recommended workflow for a "project lead" goes like this: - -1. Prepare your primary repository on your local machine. Your - work is done there. - -2. Prepare a public repository accessible to others. -+ -If other people are pulling from your repository over dumb -transport protocols (HTTP), you need to keep this repository -'dumb transport friendly'. After `git init`, -`$GIT_DIR/hooks/post-update.sample` copied from the standard templates -would contain a call to 'git update-server-info' -but you need to manually enable the hook with -`mv post-update.sample post-update`. This makes sure -'git update-server-info' keeps the necessary files up to date. - -3. Push into the public repository from your primary - repository. - -4. 'git repack' the public repository. This establishes a big - pack that contains the initial set of objects as the - baseline, and possibly 'git prune' if the transport - used for pulling from your repository supports packed - repositories. - -5. Keep working in your primary repository. Your changes - include modifications of your own, patches you receive via - e-mails, and merges resulting from pulling the "public" - repositories of your "subsystem maintainers". -+ -You can repack this private repository whenever you feel like. - -6. Push your changes to the public repository, and announce it - to the public. - -7. Every once in a while, 'git repack' the public repository. - Go back to step 5. and continue working. - - -A recommended work cycle for a "subsystem maintainer" who works -on that project and has an own "public repository" goes like this: - -1. Prepare your work repository, by running 'git clone' on the public - repository of the "project lead". The URL used for the - initial cloning is stored in the remote.origin.url - configuration variable. - -2. Prepare a public repository accessible to others, just like - the "project lead" person does. - -3. Copy over the packed files from "project lead" public - repository to your public repository, unless the "project - lead" repository lives on the same machine as yours. In the - latter case, you can use `objects/info/alternates` file to - point at the repository you are borrowing from. - -4. Push into the public repository from your primary - repository. Run 'git repack', and possibly 'git prune' if the - transport used for pulling from your repository supports - packed repositories. - -5. Keep working in your primary repository. Your changes - include modifications of your own, patches you receive via - e-mails, and merges resulting from pulling the "public" - repositories of your "project lead" and possibly your - "sub-subsystem maintainers". -+ -You can repack this private repository whenever you feel -like. - -6. Push your changes to your public repository, and ask your - "project lead" and possibly your "sub-subsystem - maintainers" to pull from it. - -7. Every once in a while, 'git repack' the public repository. - Go back to step 5. and continue working. - - -A recommended work cycle for an "individual developer" who does -not have a "public" repository is somewhat different. It goes -like this: - -1. Prepare your work repository, by 'git clone' the public - repository of the "project lead" (or a "subsystem - maintainer", if you work on a subsystem). The URL used for - the initial cloning is stored in the remote.origin.url - configuration variable. - -2. Do your work in your repository on 'master' branch. - -3. Run `git fetch origin` from the public repository of your - upstream every once in a while. This does only the first - half of `git pull` but does not merge. The head of the - public repository is stored in `.git/refs/remotes/origin/master`. - -4. Use `git cherry origin` to see which ones of your patches - were accepted, and/or use `git rebase origin` to port your - unmerged changes forward to the updated upstream. - -5. Use `git format-patch origin` to prepare patches for e-mail - submission to your upstream and send it out. Go back to - step 2. and continue. - - -Working with Others, Shared Repository Style --------------------------------------------- - -If you are coming from a CVS background, the style of cooperation -suggested in the previous section may be new to you. You do not -have to worry. Git supports the "shared public repository" style of -cooperation you are probably more familiar with as well. - -See linkgit:gitcvs-migration[7] for the details. - -Bundling your work together ---------------------------- - -It is likely that you will be working on more than one thing at -a time. It is easy to manage those more-or-less independent tasks -using branches with Git. - -We have already seen how branches work previously, -with "fun and work" example using two branches. The idea is the -same if there are more than two branches. Let's say you started -out from "master" head, and have some new code in the "master" -branch, and two independent fixes in the "commit-fix" and -"diff-fix" branches: - ------------- -$ git show-branch -! [commit-fix] Fix commit message normalization. - ! [diff-fix] Fix rename detection. - * [master] Release candidate #1 ---- - + [diff-fix] Fix rename detection. - + [diff-fix~1] Better common substring algorithm. -+ [commit-fix] Fix commit message normalization. - * [master] Release candidate #1 -++* [diff-fix~2] Pretty-print messages. ------------- - -Both fixes are tested well, and at this point, you want to merge -in both of them. You could merge in 'diff-fix' first and then -'commit-fix' next, like this: - ------------- -$ git merge -m "Merge fix in diff-fix" diff-fix -$ git merge -m "Merge fix in commit-fix" commit-fix ------------- - -Which would result in: - ------------- -$ git show-branch -! [commit-fix] Fix commit message normalization. - ! [diff-fix] Fix rename detection. - * [master] Merge fix in commit-fix ---- - - [master] Merge fix in commit-fix -+ * [commit-fix] Fix commit message normalization. - - [master~1] Merge fix in diff-fix - +* [diff-fix] Fix rename detection. - +* [diff-fix~1] Better common substring algorithm. - * [master~2] Release candidate #1 -++* [master~3] Pretty-print messages. ------------- - -However, there is no particular reason to merge in one branch -first and the other next, when what you have are a set of truly -independent changes (if the order mattered, then they are not -independent by definition). You could instead merge those two -branches into the current branch at once. First let's undo what -we just did and start over. We would want to get the master -branch before these two merges by resetting it to 'master~2': - ------------- -$ git reset --hard master~2 ------------- - -You can make sure `git show-branch` matches the state before -those two 'git merge' you just did. Then, instead of running -two 'git merge' commands in a row, you would merge these two -branch heads (this is known as 'making an Octopus'): - ------------- -$ git merge commit-fix diff-fix -$ git show-branch -! [commit-fix] Fix commit message normalization. - ! [diff-fix] Fix rename detection. - * [master] Octopus merge of branches 'diff-fix' and 'commit-fix' ---- - - [master] Octopus merge of branches 'diff-fix' and 'commit-fix' -+ * [commit-fix] Fix commit message normalization. - +* [diff-fix] Fix rename detection. - +* [diff-fix~1] Better common substring algorithm. - * [master~1] Release candidate #1 -++* [master~2] Pretty-print messages. ------------- - -Note that you should not do Octopus just because you can. An octopus -is a valid thing to do and often makes it easier to view the -commit history if you are merging more than two independent -changes at the same time. However, if you have merge conflicts -with any of the branches you are merging in and need to hand -resolve, that is an indication that the development happened in -those branches were not independent after all, and you should -merge two at a time, documenting how you resolved the conflicts, -and the reason why you preferred changes made in one side over -the other. Otherwise it would make the project history harder -to follow, not easier. - -SEE ALSO --------- -linkgit:gittutorial[7], -linkgit:gittutorial-2[7], -linkgit:gitcvs-migration[7], -linkgit:git-help[1], -linkgit:giteveryday[7], -link:user-manual.html[The Git User's Manual] - -GIT ---- -Part of the linkgit:git[1] suite |