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I have a remote repository that has a lot of branches. Every time there is a new version, a new branch is created. How can I, when a new version is available, change the branch and pull the changes avoiding to clone it all again. I want to only download the new committs.

Ayman Nedjmeddine
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Mati Halperin
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    `git fetch` does not "clone it all again". – matt Apr 16 '17 at 00:03
  • But what I want is to change the branch and sync it. So that I can use pull, push, etc. Not only fetch the commits – Mati Halperin Apr 16 '17 at 00:07
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    Possible duplicate of [How to check out a remote Git branch?](http://stackoverflow.com/questions/1783405/how-to-check-out-a-remote-git-branch) – matt Apr 16 '17 at 00:28

1 Answers1

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Executive Summery:

git fetch origin
git checkout new-version`

Where origin is the remote name and new-version is the branch name.

Details:

The documentation for git fetch says:

Fetch branches and/or tags (collectively, "refs") from one or more other repositories, along with the objects necessary to complete their histories. Remote-tracking branches are updated.

This basically means that it goes and downloads the history of the repository from the remote. However, a repository can have multiple remotes, so git fetch can fetch either one or more of them using the --all flag.

By default, any tag that points into the histories being fetched is also fetched; the effect is to fetch tags that point at branches that you are interested in. This default behavior can be changed by using the --tags or --no-tags options... By using a refspec that fetches tags explicitly, you can fetch tags that do not point into branches you are interested in as well.

Meaning that if you had, for example, branches A, B & C on the remote, and on local you were working on branch C. If you git fetch origin C, by default, this will also fetch the tags pointing to that branch, but it will not fetch those related to other branches, for instance A and B.
If you want to fetch all tags, you just add the --tags to the command.

Finally,

When no remote is specified, by default the origin remote will be used, unless there’s an upstream branch configured for the current branch.

Resources:

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Ayman Nedjmeddine
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  • Does this work with tags? Also, does this only fetch the commits needed to get up-to-date or all of the new ones? – Mati Halperin Apr 16 '17 at 00:13
  • You can think of _tags_ as branches, so yes, it does work with tags provided that you add the `--tags` to the `fetch` command. This fetches the changes for the whole repository, but you can also fetch only specific branches if you like by adding the name of the branch. i.e `git fetch origin branch-x` – Ayman Nedjmeddine Apr 16 '17 at 00:19
  • Usually you don't even need `--tags`: Git has some magic (I think "overly magic"—it's nearly inexplicable in terms of precisely what happens when) code to try to guess which tags to copy during normal `git fetch`, that mostly Just Works to get you the tags too. But use `git fetch --tags` if for some reason a tag is missing, and you will get it. – torek Apr 16 '17 at 00:21
  • @Ayman Nedjmeddine and does this work to fetch the changes from a tag that doesn't exist in the local repository because it's newer? – Mati Halperin Apr 16 '17 at 00:22
  • @Ayman Nedjmeddine Last cuestion, can I then use git pull and the new tag will get pulled, and not the old one? – Mati Halperin Apr 16 '17 at 01:09
  • @MatiHalperin, I've detailed my answer more, I hope this helps better. Please feel free to ask if something's not clear, otherwise please mark my answer ;) – Ayman Nedjmeddine Apr 16 '17 at 06:15
  • That is an explanation of how fetch works, but it is not the solution I need. I have a repository which I cloned from a remote. I used: "git clone -b tag-x remote-repo". Now I want to change "tag-x" to "tag-y" and "git pull" the changes. I hope you understand what I need – Mati Halperin Apr 16 '17 at 13:40
  • That means you still have not understood. I have explained what `fetch` does and linked to the difference between it and `pull`. Anyways: `git clone -b tag-x remote` `.... do work ....` `git fetch origin` `git checkout tag-y` `git merge origin/tag-y` `... keep working on tag-y ...` OR `git clone -b tag-x remote` `.... do work ....` `git checkout tag-y` `git pull origin tag-y` `... keep working on tag-y ...` That is what you want to do right? – Ayman Nedjmeddine Apr 16 '17 at 16:32
  • Yes, that is exactly what I want. But, if possible, use only `git pull` instead of `git pull origin tag-y` – Mati Halperin Apr 16 '17 at 20:05