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Start your free trialbrandonlind2
7,823 Pointshow does git know what change you're commiting?
I noticed with git add he put the file name he was adding, however with git commit, he just put well git commit, does git automatically assume the newest change is what is being commited, if so how you would you selectively commit something that isnt the newest thing added?
3 Answers
William Li
Courses Plus Student 26,868 PointsHi Brandon Lind
you can run
git status
this comment shows you what files have been changed since the last commit, and what files will be committed if you run git commit
.
Remember, git makes absolutely no assumption on what to commit, it only commit whatever it was told to commit. And to do so you need to manually add the changed files to the tracking stage by using git add filename
before running the git commit
; in another word, those changed files that haven't been added to the tracking stage won't get committed.
Steve Hunter
57,712 PointsHi Brandon,
You can add whichever files you like to the repository, like you say. Using git add *filename*
achieves that. From then you make an initial commit; the first benchmark. After that, any deviation from that benchmark, or subsequent ones, is committed when you ask it to.
You can commit as often as you like, indeed that is encouraged, so you are able to roll back incrementatlly, if you wish, should your project stop working after the addition of some new code. I don't think you can commit part of a change. Git watches the added files for all changes; I don't think you can select one change over another within the same file. And, I'm not sure why you'd want to - if you've committed at suitable points through the development process, you should have enough points saved to rollback to the last working model.
I hope that helps - I'm not sure it did!
Steve.
Steve Hunter
57,712 PointsYou can commit partial changes, or control large changes in multiple commits.
bothxp
16,510 PointsHi Brandon,
I'd recommend that you go and have a quick read of the git add and the git commit commands documentation. As documentation goes it's quite approachable.
Basically you use the 'git add' commands to make sure that git is aware of the changes that you have been making to files. Then you use the 'git commit' commands to well ... commit those changed files to your repository.
"git add can be performed multiple times before a commit. It only adds the content of the specified file(s) at the time the add command is run; if you want subsequent changes included in the next commit, then you must run git add again to add the new content". So I believe that if you make a change to a file, use git add to stage that file ready for your commit but then make further changes to the file then you will need to run a git add against the file again otherwise it will only commit the changes from the last add. Maybe
Running 'git commit' will commit all of the file snapshots that are currently staged using the 'git add' commands. But you can selectively commit files by using the file name as an argument to the commit command ... but I'm not sure if that will use the latest version of that file that you staged or if it will just take the file directly including any updates that you had not staged using an add.
Hmm ... I think the best think to do is to set yourself up a git repository and have a play. Have a look at the docs and try a few things out.
So as Steve has already said "I hope that helps - I'm not sure it did!"
:-)
"how does git know what change you're commiting?" - The direct answer would be that if you are not specifying a filename as part of the commit command, then it will commit all of the changes that you have previously staged using the git add
commands since your last full commit.
You can use the git status
command to get the listing of the files that are currently staged and will be committed.
bothxp
16,510 Pointsbothxp
16,510 PointsWell I guess that you can also make use of the -a switch with the commit command to automatically "add" changes from all known files.
"Tell the command to automatically stage files that have been modified and deleted, but new files you have not told Git about are not affected."
William Li
Courses Plus Student 26,868 PointsWilliam Li
Courses Plus Student 26,868 Pointscorrect, the -a flag for
git commit
is indeed a shorthand to stage changed files and commit in one go, but that's only when you would wanna commit every changes. I believe the questioner's asking about "how you would you selectively commit something that isnt the newest thing added?", no? It sounds to me that he wants to commit only some changed files but not all of 'em. Hope I didn't misinterpret his question.bothxp
16,510 Pointsbothxp
16,510 PointsHi William,
It was just for completeness, as I didn't want to leave Brandon thinking that he has to use
git add filename
to manually add the changed files to the tracking stage all the time.Can you explain how the
git commit filename
command works? I wasn't sure if it would use what had been added via agit add filename
command or would just grab the file direct?William Li
Courses Plus Student 26,868 PointsWilliam Li
Courses Plus Student 26,868 Pointshi, bothxp,
git commit filename
? I am a little confused, where's that come from? Could you elaborate?bothxp
16,510 Pointsbothxp
16,510 PointsI was thinking about the "if so how you would you selectively commit something that isnt the newest thing added?" part of the question.
I was looking at the git commit documentation
"The content to be added can be specified in several ways:
So I'd assumed that the command would take the form of
git commit filename
but I've never used that type of commit myself so I could be very wrong on that.Reading the docs more: "After staging changes to many files, you can alter the order the changes are recorded in, by giving pathnames to git commit. When pathnames are given, the command makes a commit that only records the changes made to the named paths:
This makes a commit that records the modification to Makefile. The changes staged for hello.c and hello.h are not included in the resulting commit. However, their changes are not lostβββthey are still staged and merely held back. After the above sequence, if you do:
$ git commit
this second commit would record the changes to hello.c and hello.h as expected."
William Li
Courses Plus Student 26,868 PointsWilliam Li
Courses Plus Student 26,868 PointsHi, bothxp, This, indeed, is very interesting (and complex too). To be honestly, I've used many
git commit
flags in the past, but never commit without one. So I don't have the answer myself, but tomorrow let me ask my friend who is working at Github, perhaps he knows. Will keep you posted :)bothxp
16,510 Pointsbothxp
16,510 PointsLovely thanks.
I've got a couple of books on git at home that I really need to get around to reading. My current level of git usage is more like: http://xkcd.com/1597/
William Li
Courses Plus Student 26,868 PointsWilliam Li
Courses Plus Student 26,868 PointsHi, bothxp , Sorry for the late followup.
Yeah, my friend replied my message. He said he's knows a bit
git commit filename
, however, neither he or any Githubber is using this command. Because the git tradition of staging a file viagit add
before committing selected files has its reason, as when working on a large codebase, it's very common to see many files with very similar names, going directly togit commit filename
without thegit add
step may easily committing a wrong file, it's true that git gives you many different ways to fix an unintended commit, but it's much simpler to unstage a file than to redo the commit altogether.Furthermore, he explains that
In this example and the explanation from the git documentation making it sounds more complex than it needs to be, it's actually pretty simple,
git commit file1 file2 ...
allows you to directly grab whatever changed files and commit them, without needing the extra step ofgit add
(file1, file2 must be already tracked by git).Hope this info is helpful. By the way, what git books you're currently reading? I finished this book git in practice couple months ago, it's a wonderful mid~expert level git book. Cheers.
bothxp
16,510 Pointsbothxp
16,510 PointsHi William,
Thanks for the explanation.
At the moment I've got "Version Control with Git, 2nd edition" & "Introducing GitHub". I just need to find some time to read them.