三十三、 git push简介

本文整理自： http://web.mit.edu/~mkgray/project/silk/root/afs/sipb/project/git/git-doc/git-push.html

http://apps.hi.baidu.com/share/detail/11403994

在git中，我们可以通过git push把本地仓库的更新推到服务器仓库。

$ git push ssh://git@dev.lemote.com/rt4ls.git master // 把本地仓库提交到远程仓库的master分支中
$ git remote add origin ssh://git@dev.lemote.com/rt4ls.git
$ git push origin master

这两个操作是等价的，第二个操作的第一行的意思是添加一个标记，让origin指向ssh://git@dev.lemote.com/rt4ls.git，也就是说你操作origin的时候，实际上就是在操作ssh://git@dev.lemote.com/rt4ls.git。origin在这里完全可以理解为后者的别名。

需要说明的是，默认情况下这条语句等价于提交本地的master仓库到远程仓库，并作为远程的master分支。
如果想把本地的某个分支test提交到远程仓库，并作为远程仓库的master分支，或者作为另外一个名叫test的分支，那么可以这么做。

$ git push origin test:master         // 提交本地test分支作为远程的master分支
$ git push origin test:test              // 提交本地test分支作为远程的test分支
如果想删除远程的分支呢？类似于上面，如果:左边的分支为空，那么将删除:右边的远程的分支。
$ git push origin :test              // 刚提交到远程的test将被删除，但是本地还会保存的，不用担心

更多的内容请参考《git追踪分支》

语法

DESCRIPTION

Updates remote refs using local refs, while sending objects necessary to complete the given refs.

You can make interesting things happen to a repository every time you push into it, by setting up hooks there. See documentation for git-receive-pack(1).

OPTIONS

<repository>

The "remote" repository that is destination of a push operation. This parameter can be either a URL (see the section GIT URLS below) or the name of a remote (see the section REMOTES below).

<refspec>…

The format of a <refspec> parameter is an optional plus +, followed by the source ref <src>, followed by a colon :, followed by the destination ref <dst>. It is used to specify with what <src> object the <dst> ref in the remote repository is to be updated.

The <src> is often the name of the branch you would want to push, but it can be any arbitrary "SHA-1 expression", such as master~4 or HEAD(see gitrevisions(7)).

The <dst> tells which ref on the remote side is updated with this push. Arbitrary expressions cannot be used here, an actual ref must be named. If :<dst> is omitted, the same ref as <src> will be updated.

The object referenced by <src> is used to update the <dst> reference on the remote side, but by default this is only allowed if the update can fast-forward <dst>. By having the optional leading +, you can tell git to update the <dst> ref even when the update is not a fast-forward. This does not attempt to merge <src> into <dst>. See EXAMPLES below for details.

tag <tag> means the same as refs/tags/<tag>:refs/tags/<tag>.

Pushing an empty <src> allows you to delete the <dst> ref from the remote repository.

The special refspec : (or +: to allow non-fast-forward updates) directs git to push "matching" branches: for every branch that exists on the local side, the remote side is updated if a branch of the same name already exists on the remote side. This is the default operation mode if no explicit refspec is found (that is neither on the command line nor in any Push line of the corresponding remotes file---see below).

--all

Instead of naming each ref to push, specifies that all refs under refs/heads/ be pushed.

--prune

Remove remote branches that don’t have a local counterpart. For example a remote branch tmp will be removed if a local branch with the same name doesn’t exist any more. This also respects refspecs, e.g. git push --prune remote refs/heads/*:refs/tmp/* would make sure that remoterefs/tmp/foo will be removed if refs/heads/foo doesn’t exist.

--mirror

Instead of naming each ref to push, specifies that all refs under refs/ (which includes but is not limited to refs/heads/, refs/remotes/, andrefs/tags/) be mirrored to the remote repository. Newly created local refs will be pushed to the remote end, locally updated refs will be force updated on the remote end, and deleted refs will be removed from the remote end. This is the default if the configuration optionremote.<remote>.mirror is set.

-n

--dry-run

Do everything except actually send the updates.

--porcelain

Produce machine-readable output. The output status line for each ref will be tab-separated and sent to stdout instead of stderr. The full symbolic names of the refs will be given.

--delete

All listed refs are deleted from the remote repository. This is the same as prefixing all refs with a colon.

--tags

All refs under refs/tags are pushed, in addition to refspecs explicitly listed on the command line.

--receive-pack=<git-receive-pack>

--exec=<git-receive-pack>

Path to the git-receive-pack program on the remote end. Sometimes useful when pushing to a remote repository over ssh, and you do not have the program in a directory on the default $PATH.

-f

--force

Usually, the command refuses to update a remote ref that is not an ancestor of the local ref used to overwrite it. This flag disables the check. This can cause the remote repository to lose commits; use it with care.

--repo=<repository>

This option is only relevant if no <repository> argument is passed in the invocation. In this case, git push derives the remote name from the current branch: If it tracks a remote branch, then that remote repository is pushed to. Otherwise, the name "origin" is used. For this latter case, this option can be used to override the name "origin". In other words, the difference between these two commands

git push public         #1 git push --repo=public  #2

is that #1 always pushes to "public" whereas #2 pushes to "public" only if the current branch does not track a remote branch. This is useful if you write an alias or script around git push.

-u

--set-upstream

For every branch that is up to date or successfully pushed, add upstream (tracking) reference, used by argument-less git-pull(1) and other commands. For more information, see branch.<name>.merge in git-config(1).

--thin

--no-thin

These options are passed to git-send-pack(1). A thin transfer significantly reduces the amount of sent data when the sender and receiver share many of the same objects in common. The default is --thin.

-q

--quiet

Suppress all output, including the listing of updated refs, unless an error occurs. Progress is not reported to the standard error stream.

-v

--verbose

Run verbosely.

--progress

Progress status is reported on the standard error stream by default when it is attached to a terminal, unless -q is specified. This flag forces progress status even if the standard error stream is not directed to a terminal.

--recurse-submodules=check

Check whether all submodule commits used by the revisions to be pushed are available on a remote tracking branch. Otherwise the push will be aborted and the command will exit with non-zero status.

GIT URLS

In general, URLs contain information about the transport protocol, the address of the remote server, and the path to the repository. Depending on the transport protocol, some of this information may be absent.

Git natively supports ssh, git, http, https, ftp, ftps, and rsync protocols. The following syntaxes may be used with them:

ssh://[user@]host.xz[:port]/path/to/repo.git/
git://host.xz[:port]/path/to/repo.git/
http[s]://host.xz[:port]/path/to/repo.git/
ftp[s]://host.xz[:port]/path/to/repo.git/
rsync://host.xz/path/to/repo.git/

An alternative scp-like syntax may also be used with the ssh protocol:

[user@]host.xz:path/to/repo.git/

The ssh and git protocols additionally support ~username expansion:

ssh://[user@]host.xz[:port]/~[user]/path/to/repo.git/
git://host.xz[:port]/~[user]/path/to/repo.git/
[user@]host.xz:/~[user]/path/to/repo.git/

For local repositories, also supported by git natively, the following syntaxes may be used:

/path/to/repo.git/
file:///path/to/repo.git/

These two syntaxes are mostly equivalent, except when cloning, when the former implies --local option. See git-clone(1) for details.

When git doesn’t know how to handle a certain transport protocol, it attempts to use the remote-<transport> remote helper, if one exists. To explicitly request a remote helper, the following syntax may be used:

< transport>::<address>

where <address> may be a path, a server and path, or an arbitrary URL-like string recognized by the specific remote helper being invoked. Seegit-remote-helpers(1) for details.

If there are a large number of similarly-named remote repositories and you want to use a different format for them (such that the URLs you use will be rewritten into URLs that work), you can create a configuration section of the form:

        [url "<actual url base>"]                 insteadOf = <other url base>

For example, with this:

        [url "git://git.host.xz/"]                 insteadOf = host.xz:/path/to/                 insteadOf = work:

a URL like "work:repo.git" or like "host.xz:/path/to/repo.git" will be rewritten in any context that takes a URL to be "git://git.host.xz/repo.git".

If you want to rewrite URLs for push only, you can create a configuration section of the form:

        [url "<actual url base>"]                 pushInsteadOf = <other url base>

For example, with this:

        [url "ssh://example.org/"]                 pushInsteadOf = git://example.org/

a URL like "git://example.org/path/to/repo.git" will be rewritten to "ssh://example.org/path/to/repo.git" for pushes, but pulls will still use the original URL.

REMOTES

The name of one of the following can be used instead of a URL as <repository> argument:

a remote in the git configuration file: $GIT_DIR/config,
a file in the $GIT_DIR/remotes directory, or
a file in the $GIT_DIR/branches directory.

All of these also allow you to omit the refspec from the command line because they each contain a refspec which git will use by default.

Named remote in configuration file

You can choose to provide the name of a remote which you had previously configured using git-remote(1), git-config(1) or even by a manual edit to the $GIT_DIR/config file. The URL of this remote will be used to access the repository. The refspec of this remote will be used by default when you do not provide a refspec on the command line. The entry in the config file would appear like this:

        [remote "<name>"]                 url = <url>                 pushurl = <pushurl>                 push = <refspec>                 fetch = <refspec>

The <pushurl> is used for pushes only. It is optional and defaults to <url>.

Named file in `$GIT_DIR/remotes`

You can choose to provide the name of a file in $GIT_DIR/remotes. The URL in this file will be used to access the repository. The refspec in this file will be used as default when you do not provide a refspec on the command line. This file should have the following format:

        URL: one of the above URL format         Push: <refspec>         Pull: <refspec>

Push: lines are used by git push and Pull: lines are used by git pull and git fetch. Multiple Push: and Pull: lines may be specified for additional branch mappings.

Named file in `$GIT_DIR/branches`

You can choose to provide the name of a file in $GIT_DIR/branches. The URL in this file will be used to access the repository. This file should have the following format:

        <url>#<head>

<url> is required; #<head> is optional.

Depending on the operation, git will use one of the following refspecs, if you don’t provide one on the command line. <branch> is the name of this file in $GIT_DIR/branches and <head> defaults to master.

git fetch uses:

        refs/heads/<head>:refs/heads/<branch>

git push uses:

        HEAD:refs/heads/<head>

OUTPUT

The output of "git push" depends on the transport method used; this section describes the output when pushing over the git protocol (either locally or via ssh).

The status of the push is output in tabular form, with each line representing the status of a single ref. Each line is of the form:

 <flag> <summary> <from> -> <to> (<reason>)

If --porcelain is used, then each line of the output is of the form:

 <flag> \t <from>:<to> \t <summary> (<reason>)

The status of up-to-date refs is shown only if --porcelain or --verbose option is used.

flag

A single character indicating the status of the ref:

(space): for a successfully pushed fast-forward;
+: for a successful forced update;
-: for a successfully deleted ref;
*: for a successfully pushed new ref;
!: for a ref that was rejected or failed to push; and
=: for a ref that was up to date and did not need pushing.

summary

For a successfully pushed ref, the summary shows the old and new values of the ref in a form suitable for using as an argument to git log(this is <old>..<new> in most cases, and <old>...<new> for forced non-fast-forward updates).

For a failed update, more details are given:

rejected: Git did not try to send the ref at all, typically because it is not a fast-forward and you did not force the update.
remote rejected: The remote end refused the update. Usually caused by a hook on the remote side, or because the remote repository has one of the following safety options in effect: receive.denyCurrentBranch (for pushes to the checked out branch), receive.denyNonFastForwards (for forced non-fast-forward updates), receive.denyDeletes or receive.denyDeleteCurrent. See git-config(1).
remote failure: The remote end did not report the successful update of the ref, perhaps because of a temporary error on the remote side, a break in the network connection, or other transient error.

from

The name of the local ref being pushed, minus its refs/<type>/ prefix. In the case of deletion, the name of the local ref is omitted.

to

The name of the remote ref being updated, minus its refs/<type>/ prefix.

reason

A human-readable explanation. In the case of successfully pushed refs, no explanation is needed. For a failed ref, the reason for failure is described.

Note about fast-forwards

When an update changes a branch (or more in general, a ref) that used to point at commit A to point at another commit B, it is called a fast-forward update if and only if B is a descendant of A.

In a fast-forward update from A to B, the set of commits that the original commit A built on top of is a subset of the commits the new commit B builds on top of. Hence, it does not lose any history.

In contrast, a non-fast-forward update will lose history. For example, suppose you and somebody else started at the same commit X, and you built a history leading to commit B while the other person built a history leading to commit A. The history looks like this:

---X---A

Further suppose that the other person already pushed changes leading to A back to the original repository you two obtained the original commit X.

The push done by the other person updated the branch that used to point at commit X to point at commit A. It is a fast-forward.

But if you try to push, you will attempt to update the branch (that now points at A) with commit B. This does not fast-forward. If you did so, the changes introduced by commit A will be lost, because everybody will now start building on top of B.

The command by default does not allow an update that is not a fast-forward to prevent such loss of history.

If you do not want to lose your work (history from X to B) nor the work by the other person (history from X to A), you would need to first fetch the history from the repository, create a history that contains changes done by both parties, and push the result back.

You can perform "git pull", resolve potential conflicts, and "git push" the result. A "git pull" will create a merge commit C between commits A and B.

B---C

/ /

---X---A

Updating A with the resulting merge commit will fast-forward and your push will be accepted.

Alternatively, you can rebase your change between X and B on top of A, with "git pull --rebase", and push the result back. The rebase will create a new commit D that builds the change between X and B on top of A.

B D

/ /

---X---A

Again, updating A with this commit will fast-forward and your push will be accepted.

There is another common situation where you may encounter non-fast-forward rejection when you try to push, and it is possible even when you are pushing into a repository nobody else pushes into. After you push commit A yourself (in the first picture in this section), replace it with "git commit --amend" to produce commit B, and you try to push it out, because forgot that you have pushed A out already. In such a case, and only if you are certain that nobody in the meantime fetched your earlier commit A (and started building on top of it), you can run "git push --force" to overwrite it. In other words, "git push --force" is a method reserved for a case where you do mean to lose history.

Examples

git push

Works like git push <remote>, where <remote> is the current branch’s remote (or origin, if no remote is configured for the current branch).

git push origin

Without additional configuration, works like git push origin :.

The default behavior of this command when no <refspec> is given can be configured by setting the push option of the remote.

For example, to default to pushing only the current branch to origin use git config remote.origin.push HEAD. Any valid <refspec> (like the ones in the examples below) can be configured as the default for git push origin.

git push origin :

Push "matching" branches to origin. See <refspec> in the OPTIONS section above for a description of "matching" branches.

git push origin master

Find a ref that matches master in the source repository (most likely, it would find refs/heads/master), and update the same ref (e.g.refs/heads/master) in origin repository with it. If master did not exist remotely, it would be created.

git push origin HEAD

A handy way to push the current branch to the same name on the remote.

git push origin master:satellite/master dev:satellite/dev

Use the source ref that matches master (e.g. refs/heads/master) to update the ref that matches satellite/master (most probablyrefs/remotes/satellite/master) in the origin repository, then do the same for dev and satellite/dev.

git push origin HEAD:master

Push the current branch to the remote ref matching master in the origin repository. This form is convenient to push the current branch without thinking about its local name.

git push origin master:refs/heads/experimental

Create the branch experimental in the origin repository by copying the current master branch. This form is only needed to create a new branch or tag in the remote repository when the local name and the remote name are different; otherwise, the ref name on its own will work.

git push origin :experimental

Find a ref that matches experimental in the origin repository (e.g. refs/heads/experimental), and delete it.

git push origin +dev:master

Update the origin repository’s master branch with the dev branch, allowing non-fast-forward updates. This can leave unreferenced commits dangling in the origin repository. Consider the following situation, where a fast-forward is not possible:

o---o---o---A---B origin/master

X---Y---Z dev

The above command would change the origin repository to

A---B (unnamed branch)

o---o---o---X---Y---Z master

Commits A and B would no longer belong to a branch with a symbolic name, and so would be unreachable. As such, these commits would be removed by a git gc command on the origin repository.