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1. When you are working in a small closely knit group it is not unusual to interact with the same repository over and over again By defining remote repository shorthand you can make it easier alice git remote add bob home bob myrepo With this Alice can perform the first part of the pull operation alone using the git fetch command without merging them with her own branch using alice git fetch bob Unlike the longhand form when Alice fetches from Bob using a remote repository shorthand set up with git remote what was fetched is stored in a remote tracking branch in this case bob master So after this alice git log p master bob master shows a list of all the changes that Bob made since he branched from Alice s master branch After examining those changes Alice could merge the changes into her master branch alice git merge bob master This merge can also be done by pulling from her own remote tracking branch like this alice git pull remotes bob master Note that git pull always merges into the current branch regardless of what else is given on the command line Later Bob can update his repo with Alice s latest changes using bobS git pull Note that he doesn t need to give the path to Alice s repository when Bob cloned Alice s repository git stored the location of her repository in the repository configuration and that location is used for pulls bob git config get remote origin url h
2. Bob did using a special symbol FETCH_HEAD in order to determine if he has anything worth pulling like this alice git fetch home bob myrepo master alice git log p HEAD FETCH_ HEAD This operation is safe even if Alice has uncommitted local changes The range notation HEAD FETCH_HEAD means show everything that is reachable from the FETCH_HEAD but exclude anything that is reachable from HEAD Alice already knows everything that leads to her current state HEAD and reviews what Bob has in his state FETCH_HEAD that she has not seen with this command If Alice wants to visualize what Bob did since their histories forked she can issue the following command gitk HEAD FETCH HEAD This uses the same two dot range notation we saw earlier with git log Alice may want to view what both of them did since they forked She can use three dot form instead of the two dot form gitk HEAD FETCH HEAD This means show everything that is reachable from either one but exclude anything that is reachable from both of them Please note that these range notation can be used with both gitk and git log After inspecting what Bob did if there is nothing urgent Alice may decide to continue working without pulling from Bob If Bob s history does have something Alice would immediately need Alice may choose to stash her work in progress first do a pull and then finally unstash her work in progress on top of the resulting history
3. name are usually enough git show HEAD the tip of the current branch git show experimental the tip of the experimental branch Every commit usually has one parent commit which points to the previous state of the project git show HEAD to see the parent of HEAD git show HEAD to see the grandparent of HEAD git show HEAD 4 to see the great great grandparent of HEAD Note that merge commits may have more than one parent git show HEAD 1 show the first parent of HEAD same as HEAD git show HEAD 2 show the second parent of HEAD You can also give commits names of your own after running git tag v2 5 l1b2e1d63ff you can refer to 1b2e1d63ff by the name v2 5 If you intend to share this name with other people for example to identify a release version you should create a tag object and perhaps sign it see git tag 1 for details Any git command that needs to know a commit can take any of these names For example git diff v2 5 HEAD compare the current HEAD to v2 5 git branch stable v2 5 start a new branch named stable based at v2 5 git reset hard HEAD reset your current branch and working directory to its state at HEAD Be careful with that last command in addition to losing any changes in the working directory it will also remove all later commits from this branch If this branch is the only branch containing those commits they will be lost Also don t use gi
4. now stored in a temporary staging area which git calls the index You can permanently store the contents of the index in the repository with git commit git commit This will prompt you for a commit message You ve now stored the first version of your project in git Making changes Modify some files then add their updated contents to the index git add filel file2 file3 You are now ready to commit You can see what is about to be committed using git diff with the cached option git diff cached Without cached git diff will show you any changes that you ve made but not yet added to the index You can also get a brief summary of the situation with git status git status On branch master Changes to be committed use git reset HEAD lt file gt to unstage modified filel modified file2 modified file3 If you need to make any further adjustments do so now and then add any newly modified content to the index Finally commit your changes with git commit This will again prompt you for a message describing the change and then record a new version of the project Alternatively instead of running git add beforehand you can use git commit a which will automatically notice any modified but not new files add them to the index and commit all in one step A note on commit messages Though not required it s a good idea to begin the commit message with a single sho
5. b begins with bob git clone home alice project myrepo This creates a new directory myrepo containing a clone of Alice s repository The clone is on an equal footing with the original project possessing its own copy of the original project s history Bob then makes some changes and commits them edit files bob git commit a repeat as necessary When he s ready he tells Alice to pull changes from the repository at home bob myrepo She does this with alice cd home alice project alice git pull home bob myrepo master 3 This merges the changes from Bob s master branch into Alice s current branch If Alice has made her own changes in the meantime then she may need to manually fix any conflicts The pull command thus performs two operations it fetches changes from a remote branch then merges them into the current branch Note that in general Alice would want her local changes committed before initiating this pull If Bob s work conflicts with what Alice did since their histories forked Alice will use her working tree and the index to resolve conflicts and existing local changes will interfere with the conflict resolution process git will still perform the fetch but will refuse to merge Alice will have to get rid of her local changes in some way and pull again when this happens Alice can peek at what Bob did without merging first using the fetch command this allows Alice to inspect what
6. gittutorial 7 Manual Page NAME gittutorial A tutorial introduction to git for version 1 5 1 or newer SYNOPSIS git DESCRIPTION This tutorial explains how to import a new project into git make changes to it and share changes with other developers If you are instead primarily interested in using git to fetch a project for example to test the latest version you may prefer to start with the first two chapters of The Git User s Manual First note that you can get documentation for a command such as git log graph with man git log or git help log With the latter you can use the manual viewer of your choice see git help 1 for more information It is a good idea to introduce yourself to git with your name and public email address before doing any operation The easiest way to do so is git config global user name Your Name Comes Here git config global user email you yourdomain example com Importing a new project Assume you have a tarball project tar gz with your initial work You can place it under git revision control as follows tar xzf project tar gz cd project git init Git will reply Initialized empty Git repository in git You ve now initialized the working directory you may notice a new directory created named git Next tell git to take a snapshot of the contents of all files under the current directory note the with git add git add This snapshot is
7. mmit the change and switch back to the master branch edit file git commit a git checkout master Check that the change you made is no longer visible since it was made on the experimental branch and you re back on the master branch You can make a different change on the master branch edit file git commit a at this point the two branches have diverged with different changes made in each To merge the changes made in experimental into master run git merge experimental If the changes don t conflict you re done If there are conflicts markers will be left in the problematic files showing the conflict git diff will show this Once you ve edited the files to resolve the conflicts git commit a will commit the result of the merge Finally gitk will show a nice graphical representation of the resulting history At this point you could delete the experimental branch with git branch d experimental This command ensures that the changes in the experimental branch are already in the current branch If you develop on a branch crazy idea then regret it you can always delete the branch with git branch D crazy idea Branches are cheap and easy so this is a good way to try something out Using git for collaboration Suppose that Alice has started a new project with a git repository in home alice project and that Bob who has a home directory on the same machine wants to contribute Bo
8. ome alice project The complete configuration created by git clone is visible using git config 1 and the git config 1 man page explains the meaning of each option Git also keeps a pristine copy of Alice s master branch under the name origin master bob git branch r origin master If Bob later decides to work from a different host he can still perform clones and pulls using the ssh protocol bob git clone alice org home alice project myrepo Alternatively git has a native protocol or can use rsync or http see git pull 1 for details Git can also be used in a CVS like mode with a central repository that various users push changes to see git push 1 and gitcvs migration 7 Exploring history Git history is represented as a series of interrelated commits We have already seen that the git log command can list those commits Note that first line of each git log entry also gives a name for the commit git log commit c82a22c39cbc32576f64f5c6b3 24b99ea8149C7 Author Junio C Hamano lt junkio cox net gt Date Tue May 16 17 18 22 2006 0700 merge base Clarify the comments on post processing We can give this name to git show to see the details about this commit git show c82a22c39cbc32576f64f5c6b3 24b99ea8149C7 But there are other ways to refer to commits You can use any initial part of the name that is long enough to uniquely identify the commit git show c82a22c39c the first few characters of the
9. rt less than 50 character line summarizing the change followed by a blank line and then a more thorough description Tools that turn commits into email for example use the first line on the Subject line and the rest of the commit in the body Git tracks content not files Many revision control systems provide an add command that tells the system to start tracking changes to a new file Git s add command does something simpler and more powerful git add is used both for new and newly modified files and in both cases it takes a snapshot of the given files and stages that content in the index ready for inclusion in the next commit Viewing project history At any point you can view the history of your changes using git log If you also want to see complete diffs at each step use git log p Often the overview of the change is useful to get a feel of each step git log stat summary Managing branches A single git repository can maintain multiple branches of development To create a new branch named experimental use git branch experimental If you now run git branch you ll get a list of all existing branches experimental master The experimental branch is the one you just created and the master branch is a default branch that was created for you automatically The asterisk marks the branch you are currently on type git checkout experimental to switch to the experimental branch Now edit a file co
10. s lines of development that diverged and then merged back together the order in which git log presents those commits is meaningless Most projects with multiple contributors such as the Linux kernel or git itself have frequent merges and gitk does a better job of visualizing their history For example gitk since 2 weeks ago drivers allows you to browse any commits from the last 2 weeks of commits that modified files under the drivers directory Note you can adjust gitk s fonts by holding down the control key while pressing or Finally most commands that take filenames will optionally allow you to precede any filename by a commit to specify a particular version of the file git diff v2 5 Makefile HEAD Makefile in You can also use git show to see any such file git show v2 5 Makefile Next Steps This tutorial should be enough to perform basic distributed revision control for your projects However to fully understand the depth and power of git you need to understand two simple ideas on which it is based e The object database is the rather elegant system used to store the history of your project files directories and commits e The index file is a cache of the state of a directory tree used to create commits check out working directories and hold the various trees involved in a merge Part two of this tutorial explains the object database the index file and a few other odds and ends that yo
11. t reset on a publicly visible branch that other developers pull from as it will force needless merges on other developers to clean up the history If you need to undo changes that you have pushed use git revert instead The git grep command can search for strings in any version of your project so git grep hello v2 5 searches for all occurrences of hello in v2 5 If you leave out the commit name git grep will search any of the files it manages in your current directory So git grep hello is a quick way to search just the files that are tracked by git Many git commands also take sets of commits which can be specified in a number of ways Here are some examples with git log git log V72 54 672 6 commits between v2 5 and v2 6 S git 16g V2 5 commits since v2 5 git log since 2 weeks ago commits from the last 2 weeks git log v2 5 Makefile commits since v2 5 which modify Makefile You can also give git log a range of commits where the first is not necessarily an ancestor of the second for example if the tips of the branches stable and master diverged from a common commit some time ago then git log stable master will list commits made in the master branch but not in the stable branch while git log master stable will show the list of commits made on the stable branch but not the master branch The git log command has a weakness it must present commits in a list When the history ha
12. u ll need to make the most of git You can find it at gittutorial 2 7 If you don t want to continue with that right away a few other digressions that may be interesting at this point are e git format patch 1 git am 1 These convert series of git commits into emailed patches and vice versa useful for projects such as the Linux kernel which rely heavily on emailed patches e git bisect 1 When there is a regression in your project one way to track down the bug is by searching through the history to find the exact commit that s to blame Git bisect can help you perform a binary search for that commit It is smart enough to perform a close to optimal search even in the case of complex non linear history with lots of merged branches e gitworkflows 7 Gives an overview of recommended workflows e Everyday GIT with 20 Commands Or So e gitcvs migration 7 Git for CVS users SEE ALSO gittutorial 2 7 gitcvs migration 7 gitcore tutorial 7 gitglossary 7 git help 1 gitworkflows 7 Everyday git The Git User s Manual GIT Part of the git 1 suite Last updated 2010 11 25 03 13 43 UTC

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