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diff --git a/Documentation/user-manual.txt b/Documentation/user-manual.txt index 85651b57ae..5f36f8115f 100644 --- a/Documentation/user-manual.txt +++ b/Documentation/user-manual.txt @@ -5,7 +5,7 @@ ______________________________________________ Git is a fast distributed revision control system. This manual is designed to be readable by someone with basic UNIX -command-line skills, but no previous knowledge of git. +command-line skills, but no previous knowledge of Git. <<repositories-and-branches>> and <<exploring-git-history>> explain how to fetch and study a project using git--read these chapters to learn how @@ -34,7 +34,7 @@ $ git help clone With the latter, you can use the manual viewer of your choice; see linkgit:git-help[1] for more information. -See also <<git-quick-start>> for a brief overview of git commands, +See also <<git-quick-start>> for a brief overview of Git commands, without any explanation. Finally, see <<todo>> for ways that you can help make this manual more @@ -46,10 +46,10 @@ Repositories and Branches ========================= [[how-to-get-a-git-repository]] -How to get a git repository +How to get a Git repository --------------------------- -It will be useful to have a git repository to experiment with as you +It will be useful to have a Git repository to experiment with as you read this manual. The best way to get one is by using the linkgit:git-clone[1] command to @@ -57,7 +57,7 @@ download a copy of an existing repository. If you don't already have a project in mind, here are some interesting examples: ------------------------------------------------ - # git itself (approx. 10MB download): + # Git itself (approx. 10MB download): $ git clone git://git.kernel.org/pub/scm/git/git.git # the Linux kernel (approx. 150MB download): $ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git @@ -79,7 +79,7 @@ How to check out a different version of a project Git is best thought of as a tool for storing the history of a collection of files. It stores the history as a compressed collection of -interrelated snapshots of the project's contents. In git each such +interrelated snapshots of the project's contents. In Git each such version is called a <<def_commit,commit>>. Those snapshots aren't necessarily all arranged in a single line from @@ -87,7 +87,7 @@ oldest to newest; instead, work may simultaneously proceed along parallel lines of development, called <<def_branch,branches>>, which may merge and diverge. -A single git repository can track development on multiple branches. It +A single Git repository can track development on multiple branches. It does this by keeping a list of <<def_head,heads>> which reference the latest commit on each branch; the linkgit:git-branch[1] command shows you the list of branch heads: @@ -198,7 +198,7 @@ has that commit at all). Since the object name is computed as a hash over the contents of the commit, you are guaranteed that the commit can never change without its name also changing. -In fact, in <<git-concepts>> we shall see that everything stored in git +In fact, in <<git-concepts>> we shall see that everything stored in Git history, including file data and directory contents, is stored in an object with a name that is a hash of its contents. @@ -211,7 +211,7 @@ parent commit which shows what happened before this commit. Following the chain of parents will eventually take you back to the beginning of the project. -However, the commits do not form a simple list; git allows lines of +However, the commits do not form a simple list; Git allows lines of development to diverge and then reconverge, and the point where two lines of development reconverge is called a "merge". The commit representing a merge can therefore have more than one parent, with @@ -219,8 +219,8 @@ each parent representing the most recent commit on one of the lines of development leading to that point. The best way to see how this works is using the linkgit:gitk[1] -command; running gitk now on a git repository and looking for merge -commits will help understand how the git organizes history. +command; running gitk now on a Git repository and looking for merge +commits will help understand how the Git organizes history. In the following, we say that commit X is "reachable" from commit Y if commit X is an ancestor of commit Y. Equivalently, you could say @@ -231,7 +231,7 @@ leading from commit Y to commit X. Understanding history: History diagrams ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -We will sometimes represent git history using diagrams like the one +We will sometimes represent Git history using diagrams like the one below. Commits are shown as "o", and the links between them with lines drawn with - / and \. Time goes left to right: @@ -285,7 +285,7 @@ git branch -D <branch>:: even if the branch points to a commit not reachable from the current branch, you may know that that commit is still reachable from some other branch or tag. In that - case it is safe to use this command to force git to delete + case it is safe to use this command to force Git to delete the branch. git checkout <branch>:: make the current branch <branch>, updating the working @@ -295,7 +295,7 @@ git checkout -b <new> <start-point>:: check it out. The special symbol "HEAD" can always be used to refer to the current -branch. In fact, git uses a file named "HEAD" in the .git directory to +branch. In fact, Git uses a file named "HEAD" in the .git directory to remember which branch is current: ------------------------------------------------ @@ -377,7 +377,7 @@ $ git checkout -b my-todo-copy origin/todo You can also check out "origin/todo" directly to examine it or write a one-off patch. See <<detached-head,detached head>>. -Note that the name "origin" is just the name that git uses by default +Note that the name "origin" is just the name that Git uses by default to refer to the repository that you cloned from. [[how-git-stores-references]] @@ -405,7 +405,7 @@ As another useful shortcut, the "HEAD" of a repository can be referred to just using the name of that repository. So, for example, "origin" is usually a shortcut for the HEAD branch in the repository "origin". -For the complete list of paths which git checks for references, and +For the complete list of paths which Git checks for references, and the order it uses to decide which to choose when there are multiple references with the same shorthand name, see the "SPECIFYING REVISIONS" section of linkgit:gitrevisions[7]. @@ -449,7 +449,7 @@ origin/master If you run "git fetch <remote>" later, the remote-tracking branches for the named <remote> will be updated. -If you examine the file .git/config, you will see that git has added +If you examine the file .git/config, you will see that Git has added a new stanza: ------------------------------------------------- @@ -461,13 +461,13 @@ $ cat .git/config ... ------------------------------------------------- -This is what causes git to track the remote's branches; you may modify +This is what causes Git to track the remote's branches; you may modify or delete these configuration options by editing .git/config with a text editor. (See the "CONFIGURATION FILE" section of linkgit:git-config[1] for details.) [[exploring-git-history]] -Exploring git history +Exploring Git history ===================== Git is best thought of as a tool for storing the history of a @@ -499,7 +499,7 @@ Bisecting: 3537 revisions left to test after this [65934a9a028b88e83e2b0f8b36618fe503349f8e] BLOCK: Make USB storage depend on SCSI rather than selecting it [try #6] ------------------------------------------------- -If you run "git branch" at this point, you'll see that git has +If you run "git branch" at this point, you'll see that Git has temporarily moved you in "(no branch)". HEAD is now detached from any branch and points directly to a commit (with commit id 65934...) that is reachable from "master" but not from v2.6.18. Compile and test it, @@ -511,7 +511,7 @@ Bisecting: 1769 revisions left to test after this [7eff82c8b1511017ae605f0c99ac275a7e21b867] i2c-core: Drop useless bitmaskings ------------------------------------------------- -checks out an older version. Continue like this, telling git at each +checks out an older version. Continue like this, telling Git at each stage whether the version it gives you is good or bad, and notice that the number of revisions left to test is cut approximately in half each time. @@ -549,14 +549,14 @@ then test, run "bisect good" or "bisect bad" as appropriate, and continue. Instead of "git bisect visualize" and then "git reset --hard -fb47ddb2db...", you might just want to tell git that you want to skip +fb47ddb2db...", you might just want to tell Git that you want to skip the current commit: ------------------------------------------------- $ git bisect skip ------------------------------------------------- -In this case, though, git may not eventually be able to tell the first +In this case, though, Git may not eventually be able to tell the first bad one between some first skipped commits and a later bad commit. There are also ways to automate the bisecting process if you have a @@ -685,7 +685,7 @@ See the "--pretty" option in the linkgit:git-log[1] man page for more display options. Note that git log starts with the most recent commit and works -backwards through the parents; however, since git history can contain +backwards through the parents; however, since Git history can contain multiple independent lines of development, the particular order that commits are listed in may be somewhat arbitrary. @@ -732,7 +732,7 @@ $ git show v2.5:fs/locks.c ------------------------------------------------- Before the colon may be anything that names a commit, and after it -may be any path to a file tracked by git. +may be any path to a file tracked by Git. [[history-examples]] Examples @@ -782,7 +782,7 @@ e05db0fd4f31dde7005f075a84f96b360d05984b Or you could recall that the ... operator selects all commits contained reachable from either one reference or the other but not -both: so +both; so ------------------------------------------------- $ git log origin...master @@ -931,11 +931,20 @@ The linkgit:git-archive[1] command can create a tar or zip archive from any version of a project; for example: ------------------------------------------------- -$ git archive --format=tar --prefix=project/ HEAD | gzip >latest.tar.gz +$ git archive -o latest.tar.gz --prefix=project/ HEAD ------------------------------------------------- -will use HEAD to produce a tar archive in which each filename is -preceded by "project/". +will use HEAD to produce a gzipped tar archive in which each filename +is preceded by `project/`. The output file format is inferred from +the output file extension if possible, see linkgit:git-archive[1] for +details. + +Versions of Git older than 1.7.7 don't know about the 'tar.gz' format, +you'll need to use gzip explicitly: + +------------------------------------------------- +$ git archive --format=tar --prefix=project/ HEAD | gzip >latest.tar.gz +------------------------------------------------- If you're releasing a new version of a software project, you may want to simultaneously make a changelog to include in the release @@ -984,16 +993,23 @@ student. The linkgit:git-log[1], linkgit:git-diff-tree[1], and linkgit:git-hash-object[1] man pages may prove helpful. [[Developing-With-git]] -Developing with git +Developing with Git =================== [[telling-git-your-name]] -Telling git your name +Telling Git your name --------------------- -Before creating any commits, you should introduce yourself to git. The -easiest way to do so is to make sure the following lines appear in a -file named .gitconfig in your home directory: +Before creating any commits, you should introduce yourself to Git. +The easiest way to do so is to use linkgit:git-config[1]: + +------------------------------------------------ +$ git config --global user.name 'Your Name Comes Here' +$ git config --global user.email 'you@yourdomain.example.com' +------------------------------------------------ + +Which will add the following to a file named `.gitconfig` in your +home directory: ------------------------------------------------ [user] @@ -1001,8 +1017,9 @@ file named .gitconfig in your home directory: email = you@yourdomain.example.com ------------------------------------------------ -(See the "CONFIGURATION FILE" section of linkgit:git-config[1] for -details on the configuration file.) +See the "CONFIGURATION FILE" section of linkgit:git-config[1] for +details on the configuration file. The file is plain text, so you can +also edit it with your favorite editor. [[creating-a-new-repository]] @@ -1035,13 +1052,13 @@ Creating a new commit takes three steps: 1. Making some changes to the working directory using your favorite editor. - 2. Telling git about your changes. - 3. Creating the commit using the content you told git about + 2. Telling Git about your changes. + 3. Creating the commit using the content you told Git about in step 2. In practice, you can interleave and repeat steps 1 and 2 as many times as you want: in order to keep track of what you want committed -at step 3, git maintains a snapshot of the tree's contents in a +at step 3, Git maintains a snapshot of the tree's contents in a special staging area called "the index." At the beginning, the content of the index will be identical to @@ -1094,7 +1111,7 @@ When you're ready, just run $ git commit ------------------------------------------------- -and git will prompt you for a commit message and then create the new +and Git will prompt you for a commit message and then create the new commit. Check to make sure it looks like what you expected with ------------------------------------------------- @@ -1138,7 +1155,7 @@ with a single short (less than 50 character) line summarizing the change, followed by a blank line and then a more thorough description. The text up to the first blank line in a commit message is treated as the commit title, and that title is used -throughout git. For example, linkgit:git-format-patch[1] turns a +throughout Git. For example, linkgit:git-format-patch[1] turns a commit into email, and it uses the title on the Subject line and the rest of the commit in the body. @@ -1147,15 +1164,15 @@ rest of the commit in the body. Ignoring files -------------- -A project will often generate files that you do 'not' want to track with git. +A project will often generate files that you do 'not' want to track with Git. This typically includes files generated by a build process or temporary -backup files made by your editor. Of course, 'not' tracking files with git +backup files made by your editor. Of course, 'not' tracking files with Git is just a matter of 'not' calling `git add` on them. But it quickly becomes annoying to have these untracked files lying around; e.g. they make `git add .` practically useless, and they keep showing up in the output of `git status`. -You can tell git to ignore certain files by creating a file called .gitignore +You can tell Git to ignore certain files by creating a file called .gitignore in the top level of your working directory, with contents such as: ------------------------------------------------- @@ -1181,7 +1198,7 @@ for other users who clone your repository. If you wish the exclude patterns to affect only certain repositories (instead of every repository for a given project), you may instead put them in a file in your repository named .git/info/exclude, or in any file -specified by the `core.excludesfile` configuration variable. Some git +specified by the `core.excludesfile` configuration variable. Some Git commands can also take exclude patterns directly on the command line. See linkgit:gitignore[5] for the details. @@ -1227,7 +1244,7 @@ Automatic merge failed; fix conflicts and then commit the result. Conflict markers are left in the problematic files, and after you resolve the conflicts manually, you can update the index -with the contents and run git commit, as you normally would when +with the contents and run Git commit, as you normally would when creating a new file. If you examine the resulting commit using gitk, you will see that it @@ -1238,7 +1255,7 @@ one to the top of the other branch. Resolving a merge ----------------- -When a merge isn't resolved automatically, git leaves the index and +When a merge isn't resolved automatically, Git leaves the index and the working tree in a special state that gives you all the information you need to help resolve the merge. @@ -1274,14 +1291,14 @@ some information about the merge. Normally you can just use this default message unchanged, but you may add additional commentary of your own if desired. -The above is all you need to know to resolve a simple merge. But git +The above is all you need to know to resolve a simple merge. But Git also provides more information to help resolve conflicts: [[conflict-resolution]] Getting conflict-resolution help during a merge ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -All of the changes that git was able to merge automatically are +All of the changes that Git was able to merge automatically are already added to the index file, so linkgit:git-diff[1] shows only the conflicts. It uses an unusual syntax: @@ -1413,7 +1430,7 @@ parents, one pointing at each of the two lines of development that were merged. However, if the current branch is a descendant of the other--so every -commit present in the one is already contained in the other--then git +commit present in the one is already contained in the other--then Git just performs a "fast-forward"; the head of the current branch is moved forward to point at the head of the merged-in branch, without any new commits being created. @@ -1439,7 +1456,7 @@ fundamentally different ways to fix the problem: 2. You can go back and modify the old commit. You should never do this if you have already made the history public; - git does not normally expect the "history" of a project to + Git does not normally expect the "history" of a project to change, and cannot correctly perform repeated merges from a branch that has had its history changed. @@ -1464,7 +1481,7 @@ You can also revert an earlier change, for example, the next-to-last: $ git revert HEAD^ ------------------------------------------------- -In this case git will attempt to undo the old change while leaving +In this case Git will attempt to undo the old change while leaving intact any changes made since then. If more recent changes overlap with the changes to be reverted, then you will be asked to fix conflicts manually, just as in the case of <<resolving-a-merge, @@ -1561,18 +1578,12 @@ $ git stash pop Ensuring good performance ------------------------- -On large repositories, git depends on compression to keep the history -information from taking up too much space on disk or in memory. - -This compression is not performed automatically. Therefore you -should occasionally run linkgit:git-gc[1]: - -------------------------------------------------- -$ git gc -------------------------------------------------- - -to recompress the archive. This can be very time-consuming, so -you may prefer to run `git gc` when you are not doing other work. +On large repositories, Git depends on compression to keep the history +information from taking up too much space on disk or in memory. Some +Git commands may automatically run linkgit:git-gc[1], so you don't +have to worry about running it manually. However, compressing a large +repository may take a while, so you may want to call `gc` explicitly +to avoid automatic compression kicking in when it is not convenient. [[ensuring-reliability]] @@ -1618,7 +1629,7 @@ Say you modify a branch with +linkgit:git-reset[1] \--hard+, and then realize that the branch was the only reference you had to that point in history. -Fortunately, git also keeps a log, called a "reflog", of all the +Fortunately, Git also keeps a log, called a "reflog", of all the previous values of each branch. So in this case you can still find the old history using, for example, @@ -1627,7 +1638,7 @@ $ git log master@{1} ------------------------------------------------- This lists the commits reachable from the previous version of the -"master" branch head. This syntax can be used with any git command +"master" branch head. This syntax can be used with any Git command that accepts a commit, not just with git log. Some other examples: ------------------------------------------------- @@ -1653,7 +1664,7 @@ pruned. See linkgit:git-reflog[1] and linkgit:git-gc[1] to learn how to control this pruning, and see the "SPECIFYING REVISIONS" section of linkgit:gitrevisions[7] for details. -Note that the reflog history is very different from normal git history. +Note that the reflog history is very different from normal Git history. While normal history is shared by every repository that works on the same project, the reflog history is not shared: it tells you only about how the branches in your local repository have changed over time. @@ -1787,6 +1798,13 @@ $ git format-patch origin will produce a numbered series of files in the current directory, one for each patch in the current branch but not in origin/HEAD. +`git format-patch` can include an initial "cover letter". You can insert +commentary on individual patches after the three dash line which +`format-patch` places after the commit message but before the patch +itself. If you use `git notes` to track your cover letter material, +`git format-patch --notes` will include the commit's notes in a similar +manner. + You can then import these into your mail client and send them by hand. However, if you have a lot to send at once, you may prefer to use the linkgit:git-send-email[1] script to automate the process. @@ -1809,7 +1827,7 @@ $ git am -3 patches.mbox Git will apply each patch in order; if any conflicts are found, it will stop, and you can fix the conflicts as described in "<<resolving-a-merge,Resolving a merge>>". (The "-3" option tells -git to perform a merge; if you would prefer it just to abort and +Git to perform a merge; if you would prefer it just to abort and leave your tree and index untouched, you may omit that option.) Once the index is updated with the results of the conflict @@ -1819,7 +1837,7 @@ resolution, instead of creating a new commit, just run $ git am --resolved ------------------------------------------------- -and git will create the commit for you and continue applying the +and Git will create the commit for you and continue applying the remaining patches from the mailbox. The final result will be a series of commits, one for each patch in @@ -1827,7 +1845,7 @@ the original mailbox, with authorship and commit log message each taken from the message containing each patch. [[public-repositories]] -Public git repositories +Public Git repositories ----------------------- Another way to submit changes to a project is to tell the maintainer @@ -1902,7 +1920,7 @@ public repository. You can use scp, rsync, or whatever is most convenient. [[exporting-via-git]] -Exporting a git repository via the git protocol +Exporting a Git repository via the Git protocol ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This is the preferred method. @@ -1915,7 +1933,7 @@ repository>>", below. Otherwise, all you need to do is start linkgit:git-daemon[1]; it will listen on port 9418. By default, it will allow access to any directory -that looks like a git directory and contains the magic file +that looks like a Git directory and contains the magic file git-daemon-export-ok. Passing some directory paths as `git daemon` arguments will further restrict the exports to those paths. @@ -1924,13 +1942,13 @@ linkgit:git-daemon[1] man page for details. (See especially the examples section.) [[exporting-via-http]] -Exporting a git repository via http +Exporting a git repository via HTTP ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -The git protocol gives better performance and reliability, but on a -host with a web server set up, http exports may be simpler to set up. +The Git protocol gives better performance and reliability, but on a +host with a web server set up, HTTP exports may be simpler to set up. -All you need to do is place the newly created bare git repository in +All you need to do is place the newly created bare Git repository in a directory that is exported by the web server, and make some adjustments to give web clients some extra information they need: @@ -1954,7 +1972,7 @@ $ git clone http://yourserver.com/~you/proj.git (See also link:howto/setup-git-server-over-http.txt[setup-git-server-over-http] for a slightly more sophisticated setup using WebDAV which also -allows pushing over http.) +allows pushing over HTTP.) [[pushing-changes-to-a-public-repository]] Pushing changes to a public repository @@ -1986,21 +2004,27 @@ handling this case. Note that the target of a "push" is normally a <<def_bare_repository,bare>> repository. You can also push to a -repository that has a checked-out working tree, but the working tree -will not be updated by the push. This may lead to unexpected results if -the branch you push to is the currently checked-out branch! +repository that has a checked-out working tree, but a push to update the +currently checked-out branch is denied by default to prevent confusion. +See the description of the receive.denyCurrentBranch option +in linkgit:git-config[1] for details. As with `git fetch`, you may also set up configuration options to -save typing; so, for example, after +save typing; so, for example: + +------------------------------------------------- +$ git remote add public-repo ssh://yourserver.com/~you/proj.git +------------------------------------------------- + +adds the following to `.git/config`: ------------------------------------------------- -$ cat >>.git/config <<EOF [remote "public-repo"] - url = ssh://yourserver.com/~you/proj.git -EOF + url = yourserver.com:proj.git + fetch = +refs/heads/*:refs/remotes/example/* ------------------------------------------------- -you should be able to perform the above push with just +which lets you do the same push with just ------------------------------------------------- $ git push public-repo master @@ -2039,6 +2063,13 @@ branch name with a plus sign: $ git push ssh://yourserver.com/~you/proj.git +master ------------------------------------------------- +Note the addition of the `+` sign. Alternatively, you can use the +`-f` flag to force the remote update, as in: + +------------------------------------------------- +$ git push -f ssh://yourserver.com/~you/proj.git master +------------------------------------------------- + Normally whenever a branch head in a public repository is modified, it is modified to point to a descendant of the commit that it pointed to before. By forcing a push in this situation, you break that convention. @@ -2066,9 +2097,9 @@ all push to and pull from a single shared repository. See linkgit:gitcvs-migration[7] for instructions on how to set this up. -However, while there is nothing wrong with git's support for shared +However, while there is nothing wrong with Git's support for shared repositories, this mode of operation is not generally recommended, -simply because the mode of collaboration that git supports--by +simply because the mode of collaboration that Git supports--by exchanging patches and pulling from public repositories--has so many advantages over the central shared repository: @@ -2092,8 +2123,8 @@ Allowing web browsing of a repository ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The gitweb cgi script provides users an easy way to browse your -project's files and history without having to install git; see the file -gitweb/INSTALL in the git source tree for instructions on setting it up. +project's files and history without having to install Git; see the file +gitweb/INSTALL in the Git source tree for instructions on setting it up. [[sharing-development-examples]] Examples @@ -2103,7 +2134,7 @@ Examples Maintaining topic branches for a Linux subsystem maintainer ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -This describes how Tony Luck uses git in his role as maintainer of the +This describes how Tony Luck uses Git in his role as maintainer of the IA64 architecture for the Linux kernel. He uses two public branches: @@ -2153,7 +2184,7 @@ $ git checkout release && git pull Important note! If you have any local changes in these branches, then this merge will create a commit object in the history (with no local -changes git will simply do a "fast-forward" merge). Many people dislike +changes Git will simply do a "fast-forward" merge). Many people dislike the "noise" that this creates in the Linux history, so you should avoid doing this capriciously in the "release" branch, as these noisy commits will become part of the permanent history when you ask Linus to pull @@ -2275,24 +2306,20 @@ branch and then merge into each of the test and release branches. For these changes, just apply directly to the "release" branch, and then merge that into the "test" branch. -To create diffstat and shortlog summaries of changes to include in a "please -pull" request to Linus you can use: - -------------------------------------------------- -$ git diff --stat origin..release -------------------------------------------------- - -and +After pushing your work to `mytree`, you can use +linkgit:git-request-pull[1] to prepare a "please pull" request message +to send to Linus: ------------------------------------------------- -$ git log -p origin..release | git shortlog +$ git push mytree +$ git request-pull origin mytree release ------------------------------------------------- Here are some of the scripts that simplify all this even further. ------------------------------------------------- ==== update script ==== -# Update a branch in my GIT tree. If the branch to be updated +# Update a branch in my Git tree. If the branch to be updated # is origin, then pull from kernel.org. Otherwise merge # origin/master branch into test|release branch @@ -2350,7 +2377,7 @@ esac ------------------------------------------------- ==== status script ==== -# report on status of my ia64 GIT tree +# report on status of my ia64 Git tree gb=$(tput setab 2) rb=$(tput setab 1) @@ -2406,7 +2433,7 @@ Rewriting history and maintaining patch series Normally commits are only added to a project, never taken away or replaced. Git is designed with this assumption, and violating it will -cause git's merge machinery (for example) to do the wrong thing. +cause Git's merge machinery (for example) to do the wrong thing. However, there is a situation in which it can be useful to violate this assumption. @@ -2517,7 +2544,7 @@ running `git commit`, just run $ git rebase --continue ------------------------------------------------- -and git will continue applying the rest of the patches. +and Git will continue applying the rest of the patches. At any point you may use the `--abort` option to abort this process and return mywork to the state it had before you started the rebase: @@ -2526,6 +2553,12 @@ return mywork to the state it had before you started the rebase: $ git rebase --abort ------------------------------------------------- +If you need to reorder or edit a number of commits in a branch, it may +be easier to use `git rebase -i`, which allows you to reorder and +squash commits, as well as marking them for individual editing during +the rebase. See <<interactive-rebase>> for details, and +<<reordering-patch-series>> for alternatives. + [[rewriting-one-commit]] Rewriting a single commit ------------------------- @@ -2539,72 +2572,89 @@ $ git commit --amend which will replace the old commit by a new commit incorporating your changes, giving you a chance to edit the old commit message first. +This is useful for fixing typos in your last commit, or for adjusting +the patch contents of a poorly staged commit. -You can also use a combination of this and linkgit:git-rebase[1] to -replace a commit further back in your history and recreate the -intervening changes on top of it. First, tag the problematic commit -with - -------------------------------------------------- -$ git tag bad mywork~5 -------------------------------------------------- +If you need to amend commits from deeper in your history, you can +use <<interactive-rebase,interactive rebase's `edit` instruction>>. -(Either gitk or `git log` may be useful for finding the commit.) +[[reordering-patch-series]] +Reordering or selecting from a patch series +------------------------------------------- -Then check out that commit, edit it, and rebase the rest of the series -on top of it (note that we could check out the commit on a temporary -branch, but instead we're using a <<detached-head,detached head>>): +Sometimes you want to edit a commit deeper in your history. One +approach is to use `git format-patch` to create a series of patches +and then reset the state to before the patches: ------------------------------------------------- -$ git checkout bad -$ # make changes here and update the index -$ git commit --amend -$ git rebase --onto HEAD bad mywork +$ git format-patch origin +$ git reset --hard origin ------------------------------------------------- -When you're done, you'll be left with mywork checked out, with the top -patches on mywork reapplied on top of your modified commit. You can -then clean up with +Then modify, reorder, or eliminate patches as needed before applying +them again with linkgit:git-am[1]: ------------------------------------------------- -$ git tag -d bad +$ git am *.patch ------------------------------------------------- -Note that the immutable nature of git history means that you haven't really -"modified" existing commits; instead, you have replaced the old commits with -new commits having new object names. +[[interactive-rebase]] +Using interactive rebases +------------------------- -[[reordering-patch-series]] -Reordering or selecting from a patch series -------------------------------------------- +You can also edit a patch series with an interactive rebase. This is +the same as <<reordering-patch-series,reordering a patch series using +`format-patch`>>, so use whichever interface you like best. -Given one existing commit, the linkgit:git-cherry-pick[1] command -allows you to apply the change introduced by that commit and create a -new commit that records it. So, for example, if "mywork" points to a -series of patches on top of "origin", you might do something like: +Rebase your current HEAD on the last commit you want to retain as-is. +For example, if you want to reorder the last 5 commits, use: ------------------------------------------------- -$ git checkout -b mywork-new origin -$ gitk origin..mywork & +$ git rebase -i HEAD~5 ------------------------------------------------- -and browse through the list of patches in the mywork branch using gitk, -applying them (possibly in a different order) to mywork-new using -cherry-pick, and possibly modifying them as you go using `git commit --amend`. -The linkgit:git-gui[1] command may also help as it allows you to -individually select diff hunks for inclusion in the index (by -right-clicking on the diff hunk and choosing "Stage Hunk for Commit"). - -Another technique is to use `git format-patch` to create a series of -patches, then reset the state to before the patches: +This will open your editor with a list of steps to be taken to perform +your rebase. ------------------------------------------------- -$ git format-patch origin -$ git reset --hard origin -------------------------------------------------- +pick deadbee The oneline of this commit +pick fa1afe1 The oneline of the next commit +... -Then modify, reorder, or eliminate patches as preferred before applying -them again with linkgit:git-am[1]. +# Rebase c0ffeee..deadbee onto c0ffeee +# +# Commands: +# p, pick = use commit +# r, reword = use commit, but edit the commit message +# e, edit = use commit, but stop for amending +# s, squash = use commit, but meld into previous commit +# f, fixup = like "squash", but discard this commit's log message +# x, exec = run command (the rest of the line) using shell +# +# These lines can be re-ordered; they are executed from top to bottom. +# +# If you remove a line here THAT COMMIT WILL BE LOST. +# +# However, if you remove everything, the rebase will be aborted. +# +# Note that empty commits are commented out +------------------------------------------------- + +As explained in the comments, you can reorder commits, squash them +together, edit commit messages, etc. by editing the list. Once you +are satisfied, save the list and close your editor, and the rebase +will begin. + +The rebase will stop where `pick` has been replaced with `edit` or +when a step in the list fails to mechanically resolve conflicts and +needs your help. When you are done editing and/or resolving conflicts +you can continue with `git rebase --continue`. If you decide that +things are getting too hairy, you can always bail out with `git rebase +--abort`. Even after the rebase is complete, you can still recover +the original branch by using the <<reflogs,reflog>>. + +For a more detailed discussion of the procedure and additional tips, +see the "INTERACTIVE MODE" section of linkgit:git-rebase[1]. [[patch-series-tools]] Other tools @@ -2651,7 +2701,7 @@ Git has no way of knowing that the new head is an updated version of the old head; it treats this situation exactly the same as it would if two developers had independently done the work on the old and new heads in parallel. At this point, if someone attempts to merge the new head -in to their branch, git will attempt to merge together the two (old and +in to their branch, Git will attempt to merge together the two (old and new) lines of development, instead of trying to replace the old by the new. The results are likely to be unexpected. @@ -2724,7 +2774,7 @@ linear history: Bisecting between Z and D* would hit a single culprit commit Y*, and understanding why Y* was broken would probably be easier. -Partly for this reason, many experienced git users, even when +Partly for this reason, many experienced Git users, even when working on an otherwise merge-heavy project, keep the history linear by rebasing against the latest upstream version before publishing. @@ -2745,8 +2795,8 @@ arbitrary name: $ git fetch origin todo:my-todo-work ------------------------------------------------- -The first argument, "origin", just tells git to fetch from the -repository you originally cloned from. The second argument tells git +The first argument, "origin", just tells Git to fetch from the +repository you originally cloned from. The second argument tells Git to fetch the branch named "todo" from the remote repository, and to store it locally under the name refs/heads/my-todo-work. @@ -2794,7 +2844,7 @@ resulting in a situation like: In this case, "git fetch" will fail, and print out a warning. -In that case, you can still force git to update to the new head, as +In that case, you can still force Git to update to the new head, as described in the following section. However, note that in the situation above this may mean losing the commits labeled "a" and "b", unless you've already created a reference of your own pointing to @@ -2827,7 +2877,7 @@ Configuring remote-tracking branches We saw above that "origin" is just a shortcut to refer to the repository that you originally cloned from. This information is -stored in git configuration variables, which you can see using +stored in Git configuration variables, which you can see using linkgit:git-config[1]: ------------------------------------------------- @@ -2843,48 +2893,34 @@ branch.master.merge=refs/heads/master If there are other repositories that you also use frequently, you can create similar configuration options to save typing; for example, -after ------------------------------------------------- -$ git config remote.example.url git://example.com/proj.git +$ git remote add example git://example.com/proj.git ------------------------------------------------- -then the following two commands will do the same thing: +adds the following to `.git/config`: ------------------------------------------------- -$ git fetch git://example.com/proj.git master:refs/remotes/example/master -$ git fetch example master:refs/remotes/example/master +[remote "example"] + url = git://example.com/proj.git + fetch = +refs/heads/*:refs/remotes/example/* ------------------------------------------------- -Even better, if you add one more option: +Also note that the above configuration can be performed by directly +editing the file `.git/config` instead of using linkgit:git-remote[1]. -------------------------------------------------- -$ git config remote.example.fetch master:refs/remotes/example/master -------------------------------------------------- - -then the following commands will all do the same thing: +After configuring the remote, the following three commands will do the +same thing: ------------------------------------------------- -$ git fetch git://example.com/proj.git master:refs/remotes/example/master -$ git fetch example master:refs/remotes/example/master +$ git fetch git://example.com/proj.git +refs/heads/*:refs/remotes/example/* +$ git fetch example +refs/heads/*:refs/remotes/example/* $ git fetch example ------------------------------------------------- -You can also add a "+" to force the update each time: - -------------------------------------------------- -$ git config remote.example.fetch +master:refs/remotes/example/master -------------------------------------------------- - -Don't do this unless you're sure you won't mind "git fetch" possibly -throwing away commits on 'example/master'. - -Also note that all of the above configuration can be performed by -directly editing the file .git/config instead of using -linkgit:git-config[1]. - See linkgit:git-config[1] for more details on the configuration -options mentioned above. +options mentioned above and linkgit:git-fetch[1] for more details on +the refspec syntax. [[git-concepts]] @@ -2893,7 +2929,7 @@ Git concepts Git is built on a small number of simple but powerful ideas. While it is possible to get things done without understanding them, you will find -git much more intuitive if you do. +Git much more intuitive if you do. We start with the most important, the <<def_object_database,object database>> and the <<def_index,index>>. @@ -2987,7 +3023,7 @@ As you can see, a commit is defined by: Note that a commit does not itself contain any information about what actually changed; all changes are calculated by comparing the contents of the tree referred to by this commit with the trees associated with -its parents. In particular, git does not attempt to record file renames +its parents. In particular, Git does not attempt to record file renames explicitly, though it can identify cases where the existence of the same file data at changing paths suggests a rename. (See, for example, the -M option to linkgit:git-diff[1]). @@ -3026,14 +3062,14 @@ another tree, representing the contents of a subdirectory. Since trees and blobs, like all other objects, are named by the SHA-1 hash of their contents, two trees have the same SHA-1 name if and only if their contents (including, recursively, the contents of all subdirectories) -are identical. This allows git to quickly determine the differences +are identical. This allows Git to quickly determine the differences between two related tree objects, since it can ignore any entries with identical object names. (Note: in the presence of submodules, trees may also have commits as entries. See <<submodules>> for documentation.) -Note that the files all have mode 644 or 755: git actually only pays +Note that the files all have mode 644 or 755: Git actually only pays attention to the executable bit. [[blob-object]] @@ -3094,7 +3130,7 @@ sending out a single email that tells the people the name (SHA-1 hash) of the top commit, and digitally sign that email using something like GPG/PGP. -To assist in this, git also provides the tag object... +To assist in this, Git also provides the tag object... [[tag-object]] Tag Object @@ -3127,7 +3163,7 @@ objects. (Note that linkgit:git-tag[1] can also be used to create references whose names begin with "refs/tags/"). [[pack-files]] -How git stores objects efficiently: pack files +How Git stores objects efficiently: pack files ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Newly created objects are initially created in a file named after the @@ -3145,7 +3181,7 @@ The first number is the number of objects which are kept in individual files. The second is the amount of space taken up by those "loose" objects. -You can save space and make git faster by moving these loose objects in +You can save space and make Git faster by moving these loose objects in to a "pack file", which stores a group of objects in an efficient compressed format; the details of how pack files are formatted can be found in link:technical/pack-format.txt[technical/pack-format.txt]. @@ -3278,12 +3314,12 @@ repository is a *BAD* idea). Recovering from repository corruption ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -By design, git treats data trusted to it with caution. However, even in -the absence of bugs in git itself, it is still possible that hardware or +By design, Git treats data trusted to it with caution. However, even in +the absence of bugs in Git itself, it is still possible that hardware or operating system errors could corrupt data. The first defense against such problems is backups. You can back up a -git directory using clone, or just using cp, tar, or any other backup +Git directory using clone, or just using cp, tar, or any other backup mechanism. As a last resort, you can search for the corrupted objects and attempt @@ -3389,7 +3425,7 @@ $ git log --raw --all ------------------------------------------------ and just looked for the sha of the missing object (4b9458b..) in that -whole thing. It's up to you - git does *have* a lot of information, it is +whole thing. It's up to you--Git does *have* a lot of information, it is just missing one particular blob version. [[the-index]] @@ -3431,7 +3467,7 @@ It does this by storing some additional data for each entry (such as the last modified time). This data is not displayed above, and is not stored in the created tree object, but it can be used to determine quickly which files in the working directory differ from what was -stored in the index, and thus save git from having to read all of the +stored in the index, and thus save Git from having to read all of the data from such files to look for changes. 3. It can efficiently represent information about merge conflicts @@ -3662,9 +3698,9 @@ Did you forget to 'git add'? Unable to checkout '261dfac35cb99d380eb966e102c1197139f7fa24' in submodule path 'a' ------------------------------------------------- -In older git versions it could be easily forgotten to commit new or modified +In older Git versions it could be easily forgotten to commit new or modified files in a submodule, which silently leads to similar problems as not pushing -the submodule changes. Starting with git 1.7.0 both "git status" and "git diff" +the submodule changes. Starting with Git 1.7.0 both "git status" and "git diff" in the superproject show submodules as modified when they contain new or modified files to protect against accidentally committing such a state. "git diff" will also add a "-dirty" to the work tree side when generating patch @@ -3704,15 +3740,17 @@ module a NOTE: The changes are still visible in the submodule's reflog. -This is not the case if you did not commit your changes. +If you have uncommitted changes in your submodule working tree, `git +submodule update` will not overwrite them. Instead, you get the usual +warning about not being able switch from a dirty branch. [[low-level-operations]] -Low-level git operations +Low-level Git operations ======================== Many of the higher-level commands were originally implemented as shell -scripts using a smaller core of low-level git commands. These can still -be useful when doing unusual things with git, or just as a way to +scripts using a smaller core of low-level Git commands. These can still +be useful when doing unusual things with Git, or just as a way to understand its inner workings. [[object-manipulation]] @@ -3743,7 +3781,7 @@ between the working tree, the index, and the object database. Git provides low-level operations which perform each of these steps individually. -Generally, all "git" operations work on the index file. Some operations +Generally, all Git operations work on the index file. Some operations work *purely* on the index file (showing the current state of the index), but most operations move data between the index file and either the database or the working directory. Thus there are four main @@ -3766,7 +3804,7 @@ but to avoid common mistakes with filename globbing etc, the command will not normally add totally new entries or remove old entries, i.e. it will normally just update existing cache entries. -To tell git that yes, you really do realize that certain files no +To tell Git that yes, you really do realize that certain files no longer exist, or that new files should be added, you should use the `--remove` and `--add` flags respectively. @@ -3880,7 +3918,7 @@ redirection from a pipe or file, or by just typing it at the tty). `git commit-tree` will return the name of the object that represents that commit, and you should save it away for later use. Normally, -you'd commit a new `HEAD` state, and while git doesn't care where you +you'd commit a new `HEAD` state, and while Git doesn't care where you save the note about that state, in practice we tend to just write the result to the file pointed at by `.git/HEAD`, so that we can always see what the last committed state was. @@ -4037,7 +4075,7 @@ $ git ls-files --unmerged Each line of the `git ls-files --unmerged` output begins with the blob mode bits, blob SHA-1, 'stage number', and the -filename. The 'stage number' is git's way to say which tree it +filename. The 'stage number' is Git's way to say which tree it came from: stage 1 corresponds to the `$orig` tree, stage 2 to the `HEAD` tree, and stage 3 to the `$target` tree. @@ -4049,7 +4087,7 @@ obviously the final outcome is what is in `HEAD`. What the above example shows is that file `hello.c` was changed from `$orig` to `HEAD` and `$orig` to `$target` in a different way. You could resolve this by running your favorite 3-way merge -program, e.g. `diff3`, `merge`, or git's own merge-file, on +program, e.g. `diff3`, `merge`, or Git's own merge-file, on the blob objects from these three stages yourself, like this: ------------------------------------------------ @@ -4061,7 +4099,7 @@ $ git merge-file hello.c~2 hello.c~1 hello.c~3 This would leave the merge result in `hello.c~2` file, along with conflict markers if there are conflicts. After verifying -the merge result makes sense, you can tell git what the final +the merge result makes sense, you can tell Git what the final merge result for this file is by: ------------------------------------------------- @@ -4070,11 +4108,11 @@ $ git update-index hello.c ------------------------------------------------- When a path is in the "unmerged" state, running `git update-index` for -that path tells git to mark the path resolved. +that path tells Git to mark the path resolved. -The above is the description of a git merge at the lowest level, +The above is the description of a Git merge at the lowest level, to help you understand what conceptually happens under the hood. -In practice, nobody, not even git itself, runs `git cat-file` three times +In practice, nobody, not even Git itself, runs `git cat-file` three times for this. There is a `git merge-index` program that extracts the stages to temporary files and calls a "merge" script on it: @@ -4085,11 +4123,11 @@ $ git merge-index git-merge-one-file hello.c and that is what higher level `git merge -s resolve` is implemented with. [[hacking-git]] -Hacking git +Hacking Git =========== -This chapter covers internal details of the git implementation which -probably only git developers need to understand. +This chapter covers internal details of the Git implementation which +probably only Git developers need to understand. [[object-details]] Object storage format @@ -4107,7 +4145,7 @@ about the data in the object. It's worth noting that the SHA-1 hash that is used to name the object is the hash of the original data plus this header, so `sha1sum` 'file' does not match the object name for 'file'. -(Historical note: in the dawn of the age of git the hash +(Historical note: in the dawn of the age of Git the hash was the SHA-1 of the 'compressed' object.) As a result, the general consistency of an object can always be tested @@ -4137,7 +4175,7 @@ A good place to start is with the contents of the initial commit, with: $ git checkout e83c5163 ---------------------------------------------------- -The initial revision lays the foundation for almost everything git has +The initial revision lays the foundation for almost everything Git has today, but is small enough to read in one sitting. Note that terminology has changed since that revision. For example, the @@ -4291,7 +4329,7 @@ Now, for the meat: This is how you read a blob (actually, not only a blob, but any type of object). To know how the function `read_object_with_reference()` actually works, find the source code for it (something like `git grep -read_object_with | grep ":[a-z]"` in the git repository), and read +read_object_with | grep ":[a-z]"` in the Git repository), and read the source. To find out how the result can be used, just read on in `cmd_cat_file()`: @@ -4472,7 +4510,7 @@ $ git bisect bad # if this revision is bad. Making changes -------------- -Make sure git knows who to blame: +Make sure Git knows who to blame: ------------------------------------------------ $ cat >>~/.gitconfig <<\EOF @@ -4522,7 +4560,7 @@ $ git format-patch origin..HEAD # format a patch for each commit $ git am mbox # import patches from the mailbox "mbox" ----------------------------------------------- -Fetch a branch in a different git repository, then merge into the +Fetch a branch in a different Git repository, then merge into the current branch: ----------------------------------------------- @@ -4583,7 +4621,7 @@ The basic requirements: - It must be readable in order, from beginning to end, by someone intelligent with a basic grasp of the UNIX command line, but without - any special knowledge of git. If necessary, any other prerequisites + any special knowledge of Git. If necessary, any other prerequisites should be specifically mentioned as they arise. - Whenever possible, section headings should clearly describe the task they explain how to do, in language that requires no more knowledge |