Hi I'm a total newbie using git I read a few StackOverflow Q&A on this error but didn't understand how my problem relates to others with the same error message. So I didn't dare to chance it and loose 6 hours of work that I need to push to my remote GitHub repo.
.
1.) The Beginning
So my code in the local working directory got broken and I couldn't figure out what the problem was. So I wanted git to go back to the latest working version of my project. I then found this tutorial and managed to get my local project to go back to a working version.
https://www.git-tower.com/learn/git/faq/restore-repo-to-previous-revision
$ git reset --hard <SHA-1 HASH NUMBERS>
.
2.) Trying to push
These are the commands I usually follow when I want to push local code to my remote repo.
# Pushing Changes - Staging
$ git diff
$ git status
$ git add -A
$ git status
$ git commit -m "Modified multiply function."
# Pushing Changes - Repository
$ git pull origin master
$ git push origin master
.
3.) The error
I don't understand what the error message is trying to tell me. Can somebody help me by showing what sequence of commands I need to run to be able to push code like usual again?
penguin#linux$ git push origin master
To git#github.com:<name>/<project>.git
! [rejected] master -> master (non-fast-forward) error: failed to push some refs to 'git#github.com:<name>/<project>.git'
hint: Updates were rejected because a pushed branch tip is behind its remote
hint: counterpart. Check out this branch and integrate the remote changes
hint: (e.g. 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.
Let's address this rather long comment (which I should do in another comment, but this won't fit at all so I'm answering a different question, namely, "how does detaching and reattaching HEAD work"):
Tnx torek I managed to force away that error with the link you provided. I also had some detached HEAD issues which I got rid by following Razan Paul's post here Fix a Git detached head? But all my changes while in detached HEAD mode was lost after the fixes. I have copies so I can just recreate them manually I guess. So in the future when I want to go back to the latest working version on my local working directory. What procedure will suite my situation best? I see so many different suggestions I don't know what's best for me
(incidentally, when addressing a comment to someone in particular you may want to use the #<name> syntax so they get alerted).
What you need is a proper Git book. The best free one is, in my opinion, the Pro Git 2 book. (There are not many, if any, other free ones so "best" could be vacuously true here. :-) ) A shorter, non-book reference that I find helpful is Think Like (a) Git, because Git is built atop some very simple bits of graph theory—but unless you know this, and until you realize this, you're stuck in this xkcd cartoon.
(I even have my own start on a book, but I have very little time to work on it these days.)
There are many work-flows you can use in Git. The first thing to remember, though, is that Git's "unit of storage" as it were—the thing it desperately tries to protect, so that you can get it back—is the commit. That's why you were having trouble pushing: you were telling some other Git: throw away some commits. Git does not want to do that.
Commits are uniquely identified by their hash IDs. These hash IDs are not very useful to humans, so Git gives us things like branch names to remember particular IDs—but in some cases you may have to resort to raw IDs, which you can cut and paste with your mouse, for instance.
Git's desire to keep commits around means that when you make commits using a detached HEAD, Git tries to keep those too. It will do so for, by default, at least 30 days. You can find the hash IDs using git reflog. If you use git reset --hard to make Git "forget" commits that were on a branch (rather than a detached HEAD), Git keeps those IDs around for at least 30 days as well, on the branch name's reflog. There's one reflog for each branch name, and one for HEAD itself.
Last, an attached HEAD—attached being the opposite of detached—is when you are, as git status will say, "on" some particular branch:
$ git status
On branch master
...
In this case, the branch name master is how Git actually identifies which commit you have checked out right now; and the name HEAD is simply attached to the name master.
To make this all work right, Git works backwards.
A brief introduction to graphs
To really comprehend what all this means, you need to draw the commit graph. Remember that each commit has its own unique hash ID—those big ugly 40-character-long strings of a hexadecimal number, like 5be1f00a9a701532232f57958efab4be8c959a29—but that's kind of unweildy, so you might want to just use single letters for small drawings:
A <-B <-C <--master
This is a pretty-new repository with just three commits in it. We made A first, then we made B, then we made C. (We'll run out of names for commits when we get to our 27th commit, so you can see why Git uses longer hash IDs.)
Since Git works backwards, the name master identifies, not commit A, but rather commit C. We say that the name master points to C.
Commit C, being our third commit, has inside it the name—the hash ID—of our second commit, commit B. We say that C's parent commit is B. So commit C points to B. Likewise, B has inside it the hash ID of commit A, so B points back to A.
Commit A was the first commit. It can't point back to a previous commit, so it just doesn't. This makes commit A special: it's a root commit. Every non-empty repository has at least one of these, the first commit ever made.
When you run git log, Git will start with your current commit—commit C, here—and work backwards: it shows you C, and then since C points back to B, Git shows B too. Since B points back to A, Git shows A as well; but A is a root commit, so Git can stop.
How branches grow
Since we're on master, let's make a new commit D. We'll do whatever we want with the source, git add files, and run git commit to create D.
Where will D point back to? Well, obviously it has to point back to C. So Git makes D have a parent commit of C:
A <-B <-C <-D
Git's final step here is to change the name master so that it holds the hash ID of commit D, giving us this picture:
A <-B <-C <-D <--master
Note that all the arrows necessarily point backwards. Moreover, all the arrows that are inside commits are frozen for all time: D points back to C, never anywhere else. The only arrow that changes is the one coming out of the branch name! So I tend to draw them without the internal arrows, to save space and make it fit better:
A--B--C--D <-- master
This is another key to understanding Git: branch names move, over time. Branches acquire new commits, and the names point to the last commit on the branch—what Git calls the tip commit. Git uses this tip commit to find the next-older commit for that branch: the tip's parent. Git uses that commit to find its previous commit, and so on, all the way back to the root commit.
The name HEAD normally just identifies a branch name
Let's complicate-up the above repository by adding a branch coming out of C:
A--B--C--D <-- master
\
E <-- develop
Here, we now have two branches. The name develop identifies commit E, whose parent is C. If we now run:
git checkout master
we'll be on branch master, as git status will say; if we create a new commit F now, its parent will be D. If we instead git checkout develop and create a new commit F, its parent will be E instead. So Git needs to know: which branch are we on? This is where we need to draw in the name HEAD:
A--B--C--D <-- master (HEAD)
\
E <-- develop
or:
A--B--C--D <-- master
\
E <-- develop (HEAD)
When your HEAD is attached like this, it's attached to a branch name. When you make new commits, Git will change the branch name so that it points to the new commit you just made.
A "detached HEAD" simply holds the commit hash ID directly
If you find yourself in detached HEAD mode, it's usually because you checked out an older commit directly. For instance, let's check out commit B, while keeping everything we have:
A--B <-- HEAD
\
C--D <-- master
\
E <-- develop
I had to bend the graph lines around to fit HEAD in, but now HEAD points directly to commit B.
If we now make a new commit F, its parent will be B, and Git will make HEAD point directly to F:
A--B--F <-- HEAD
\
C--D <-- master
\
E <-- develop
Note that whenever Git creates a new commit, the commit to which HEAD points—directly, if detached, or indirectly, if attached to a branch name—also changes! The new commit's parent is always whatever was HEAD just a moment ago, and now HEAD is the new commit, which is once again the current commit.
(This is also why parents don't know their children's hash IDs, but a child does know its own parent's ID. Git has to work backwards, because children know their parents: the parent commits exist when the child is created; but parent commits—which are read-only and frozen in time—don't know what children they will acquire in the future.)
As soon as we re-attach HEAD, though, we "lose" the ID of commit F:
A--B--F <-- ???
\
C--D <-- master (HEAD)
\
E <-- develop
Who remembers F's ID? The answer is: only the reflogs.
If you want to hang on to commit F, you should find its ID in your reflogs and attach a name to it—a branch or tag name, usually:
A--B--F <-- newbranch
\
C--D <-- master (HEAD)
\
E <-- develop
Now newbranch remembers the ID of F. If you'd made two commits, F and G, while you had a detached HEAD, you'd have to find the later one somehow and make sure your name points to G, so that you have:
G <-- newbranch
/
A--B--F
\
C--D <-- master (HEAD)
\
E <-- develop
and not:
G <-- ???
/
A--B--F <-- newbranch
\
C--D <-- master (HEAD)
\
E <-- develop
This is why making a lot of commits on a detached HEAD is not a great idea: it can be really hard to tell, from hash IDs, which commit is the tip-most.
The git it clearly mentioning that the current branch in which your working is not updated with remote repository as others have committed their code to that repository.
First you need to take a pull of remote repository and then commit your code
NOTE : Here origin is your remote repository location which you
might have added
Eg: Considering that your working on master branch
git pull origin master /* To update with the remote repository */
git push origin master /* To push your updated code */
Related
For a nodejs command-line tool I add an empty commit to a repo and then want to remove it later.
Later I have at least 3 commits. The first one is a merge commit, the second one is the empty one I created and the third one is likely one from another now merged repo. Now that my tool has done it's task I want to remove the empty commit.
git rebase --onto emptyCommitID^ emptyCommitID
resulted in: fatal: Does not point to a valid commit 'emptyCommitID^'
(since the ID is the correct one I assume the commit is invalid due to it being empty)
git rebase --keep-base --onto thirdCommit^ headCommit
resulted in fatal: cannot combine '--keep-base' with '--onto'
trying rebase -i HEAD~3 after the tool had done it's main job resulted in:fatal: invalid upstream 'HEAD~3' which might be due to either the empty commit or the merged unrelated histories idk.
I do not want to use git filter-branch --prune-empty, because the tool shall leave other potentially empty commits untouched.
(The tool is for merging repos with unrelated histories. I create the empty commit so that files are staged when merged instead of committed directly which also happens when the --no-commit flag is set in an just initialized repo without prior commits)
maybe it is possible to solve this with git rebase --interactive, but I had the described problem with the invalid upstream and view this as very difficult to implement with a command line tool, mostly using exec to execute it's commands. Do you know a solution?
I think git rebase --onto emptyCommitID^ emptyCommitID should work.
fatal: Does not point to a valid commit 'emptyCommitID^' means that the emptyCommitID has no parent. It contradicts that the second one is the empty one and the first one is its parent.
I am using nodegit to checkout from clone and Open it to do something.
My code like this:
//repo is a Repository from Clone() or Open()
//branchName is your branch name, of course
repo.getBranch('refs/remotes/origin/' + branchName)
.then(function(reference) {
//checkout branch
return repo.checkoutRef(reference);
});
But after that I cd in to branch directory and typing the command like this
git status
or git branch
It's show a red line like this
HEAD detached at origin/branchname
How can I solved it?
Thanks
In general,1 origin/somebranch is not a branch name, and therefore git checkout origin/somebranch results in a detached HEAD, exactly as you are seeing.
Branch names, in Git, don't really do any good, to a first approximation.2 So there's no need to use them. To understand how and why this is the case, let's note that in Git, there are many kinds of names.
A branch name is simply a name which, when spelled out in full, begins with refs/heads/. The branch names master or main, for instance, are really refs/heads/master and refs/heads/main, correspondingly.
A tag name is a name which, when spelled out in full, begins with refs/tags/. So v2.1 is really refs/tags/v2.1.
Git calls these things—these names in general, before they're split into some particular classification—refs or references. Each reference holds one (1) hash ID. The hash ID is what really matters to Git. That's what Git needs. That's what git checkout requires: a hash ID. You can give it any valid commit hash ID, and it will check out that commit.
Hash IDs, though, are big and ugly and look random (though they're not). They are thoroughly unmemorable. What commit is 225365fb5195e804274ab569ac3cc4919451dc7f anyway? If I say v2.31.0-rc0, that probably means something—or at least, seems suggestive of something—to you; but if I say 2253blah you have probably forgotten the 2253 part long before I get to the dc7f part. So refs are for humans. They're not for Git, which only really cares about the hash IDs.
You only need a ref—such as a branch name—if you're a human. If you're a build system, a hash ID is fine. If you're writing part of a build system, just use a hash ID. If you're writing something for a human to use ... well, humans are hard.
Git has a special thing it calls "DWIM", or Do What I Mean, mode. If you run:
git checkout foobranch
and there is no branch named foobranch right now, Git will assume that you mean: Find me a name that resembles foobranch, such as origin/foobranch. Then use that name to make a branch name for me. You can disable this with git checkout --no-guess and sometimes that's a good idea. But sometimes this DWIM mode is exactly what you want.
Note, however, that if the pesky human went and made his own foobranch earlier, not related to origin/foobranch, this git checkout foobranch will get his foobranch, not related to origin/foobranch. So be careful: humans are tricky and weird. They do illogical, unexpected things.
Now, there's a reason humans often want to use a branch name, rather than any other name that results in the detached-HEAD mode. The primary reason they like this is because then, if they make a new commit, Git will change the hash ID stored in the branch name. The new commit will automatically link, backwards, to whatever commit was the one stored in the reference. Then Git will update the branch name so that it now stores the hash ID of the new commit.
This feature is exclusive to branch names. No other kind of name has this special feature. You can select detached-HEAD mode when using a branch name, by running git checkout --detach foobranch for instance. But the default is that when you use git checkout with a branch name—even one that DWIM mode is going to have to create—Git will instead go into attached HEAD mode.3 So that's why humans like branch names, and that's what Git does with them, that it doesn't do with any other reference name.
If you need to accommodate humans, you can do that by letting the DWIM mode do its thing here. That won't satisfy all humans, so watch out. It also won't work in some cases, so watch out. The detached-HEAD mode always works, though.
In NodeGit specifically, you have Branch.create as an async class method of Branch.. You also have Branch.lookup. You could use this to look up a remote-tracking name, like origin/branchname, and use that to create a new local branch, if that's your goal. But as before, watch out for all these various edge cases.
1It is possible to make a (local) branch named origin/somebranch, so that it is a branch name. The result is very confusing unless you carefully call out all names using their full spellings. Don't do this!
2Of course, they do do some good, so the first approximation is pretty rough.
3Git does not call it this, but what else could the right phrase for "opposite of detached HEAD" mode be?
I use GitHub in my project in Android Studio 3.3.1.
I write code in local master branch and push them to remote origin/master.
The Submit_3 Image is my latest work and submit result snapshot.
I find the code after Submit_1 Image snapshot are wrong, so I hope to return Submit_1 and write new code. I hope that I can do the new work still on master branch, how can I do?
BTW, at present I use Checkout Revision command to return to Submit_1 (see Current Image), and create a temp branch for Submit_1, then switch to master branch and merge temp branch.
But I find the result just like Result Image is the same Submit_3 Image, why?
Submit_3 Image
Submit_1 Image
Current Image
Result Image
The reason you have the same result after you merge temp is because you essentially merge what is in master (which includes the wrong thing) and the one in temp; thus, having both the wrong and correct code.
Solution to your initial problem:
git checkout master => Goes to master branch
git log -n [some number] => Shows you the list of commit messages; eg. git log -n 5 will show you last 5 commit messages.
Find the commit number of the commit you want to return to. Copy it.
git reset --hard [commit number here] => This will return master to be where you chose in your commit number. Be careful, this will erase everything that came after that commit.
I don't recall if you need to git push or it does it for you. Check by doing git status
Continue writing your code. If you have new stuff in temp, at this point, if you do git merge temp. It will get your new stuff and not have the wrong code that was in master before. If anything goes wrong, do what I described above to return to any commit.
Good luck!
Also, official doc here: https://git-scm.com/docs/git-reset
I am not sure I understand your problem but I think what you want is Reset Current Branch to Here.... This will delete Submit 2 and Submit 3 and go back in time to Submit 1. You will have in your tree:
Submit 1 (master)
Initial Commit
Then, to make this real in GitHub you need to Push Force when you push your changes. And the final tree will be:
Submit 1 (origin & master)
Initial Commit
PLEASE do this carefully. After you push force, Submit 2 and Submit 3 will be permanently deleted.
This question already has an answer here:
git checkout --ours does not remove files from unmerged files list
(1 answer)
Closed 3 years ago.
I'm trying to resolve merge conflict in some files
both modified: myFile.h
I ran this command:
git checkout --ours myFile.h
after that I ran:
git status
It shows this:
both modified: myFile.h
Why still shows "both modified" ?
Some git checkout commands resolve a merge conflict, taking the version you checked out, and some don't. This is one of the cases that don't.
You must therefore mark the conflict as resolved manually, with: git add myFile.h.
Why this is the way it is
Merging (the action, i.e., merge-as-a-verb) is done through Git's index (also called the staging area or sometimes the cache). The index has one entry for each file that will go into the next commit you make. Normally, that one entry holds one file—but the index has four slots per entry, which are numbered. Slot zero (0) is the normal "no conflict, file is ready to commit" slot. Slots 1, 2, and 3 are used only during a merge conflict, and contain the merge base version (slot 1), --ours version (slot 2), and --theirs version (slot 3).
If slot zero is filled, the other three slots are empty. If any of the other slots are filled, slot 0 is empty and the file is in "conflicted" state. (It's possible to have just two of the other three slots filled, as is the case for add/add, modify/delete, and rename/delete conflicts.)
When you run git checkout commit -- path,1 Git copies a file from the given commit into slot zero, then from slot zero to the work-tree. Copying to slot zero wipes out slots 1-3 if they're filled, so the file is now resolved!
But, when you run git checkout --ours -- path, Git doesn't have to write anything to index slot zero, it can just get the file's contents from slot 2. So it copies from slot 2 to the work-tree, and the file is not resolved.
Note that this means you can do git checkout HEAD -- path to extract the file from the HEAD commit, writing to slot zero and thus resolving as well as writing to the work-tree. This is subtly different in another way, though. Suppose that during the merge, Git decided that the file was renamed as well as being modified. It's taken the rename into account: the file's new name is evil/zorg instead of the old name evil-zorg. If you git checkout --ours, Git will extract the old (HEAD) version of evil-zorg under the new name evil/zorg. If you git checkout HEAD, Git won't find the file under the new name!
(This is another case of Git letting implementation details show through—or, equivalently, of cramming too much stuff into one command.)
1The reason for the -- is to handle a file whose name looks like an option. (For instance, what if the file's name is --theirs?) If the path part doesn't look like an option, you don't need the --. It's a good habit to pick up, though: use the -- every time and you won't be surprised someday when your file name does resemble an option.
I've been working on a project for some time using a git local repository for version control.
I have two branches in the repository: master and "other" (not its real name).
When I run git branch I get this list:
other
* master
Looking at my repository graph with gitg (a Gnome GUI for git), selecting "all branches" from the branches drop-down list, I get this graph:
I see the two branches, but there are also two commits, tagged "v1.2y" and "v1.2s", that stick out of the master branch and don't seem to merge back into it. They seem to be hanging there like non-merged-back branches, but they are not actual branches. At least neither git nor gitg list them as being branches.
Can someone explain to me the reason they stick out of the master branch if they are not branches themselves?
Please don't just simply tell me what to do to make it normal but, most importantly, the reason why this happened to begin with.
EDIT: I have never made a rebase or force push.
First of all, you can read about the difference between tags and branches here:
How is a tag different from a branch? Which should I use, here?
Suppose you do the following:
git checkout master //go to branch master, say at commit x
git checkout -b newbranch //create a new branch called newbranch that also points to x
git commit -a -m some_branch_commit_1 //add a commit to newbranch
git tag tagged_my_commit //tag your commit
git checkout master //go back to master
git commit -a -m "Something" //add a commit, say y to master
git checkout newbranch //go back to newbranch
git rebase master //create a copy of the commits on newbranch so that they now split of from y instead of x
In this case, a new copy of commit some_branch_commit_1 will be created. However, the old one still exists (it was tagged tagged_my_commit) so it will never disappear.
Basically, you now have two copies of the same commit, one of them is not on a branch with a particular name.
Suppose however you didn't tag that commit, then in principle it could be removed by git. However, deleting such commits (garbage collection) only happens from time to time. This can explain why commits that shouldn't keep on existing still are in your repostiroy. If you want to read more, see https://git-scm.com/docs/git-gc
As noted in the comments, this does not only happen with rebases. Any form of rewriting (e.g., amending commits, changing the pointer of a branch, ...) can lead you to this situation.
EDIT as requested: another example
git checkout master //go to master, say at commit x
git commit -a -m "I did something" //create a commit, say y1
git tag tagit //tag your commit
your history now looks like this
y1 = master = tagit
|
x
Now do the following
//edit some file
git commit -a -m "I did something (more)" --amend //change commit y1 such that it now also takes changes to the other file into account, say this is y2
In that case your history looks like this
y1=tagit y2=master
| /
| /
| /
| /
| /
| /
| /
| /
x
which seems to be like in your situation