git clone简介

翻译整理自： http://web.mit.edu/~mkgray/project/silk/root/afs/sipb/project/git/git-doc/git-clone.html

 在使用git来进行版本控制时，为了得一个项目的拷贝(copy),我们需要知道这个项目仓库的地址(Git URL). Git能在许多协议下使用，所以Git URL可能以ssh://, http(s)://, git://,或是只是以一个用户名（git 会认为这是一个ssh 地址）为前辍. 

有些仓库可以通过不只一种协议来访问，例如，Git本身的源代码你既可以用 git:// 协议来访问：

git clone git://git.kernel.org/pub/scm/git/git.git

也可以通过http 协议来访问:

git clone http://www.kernel.org/pub/scm/git/git.git

git://协议较为快速和有效,但是有时必须使用http协议,比如你公司的防火墙阻止了你的非http访问请求.如果你执行了上面两行命令中的任意一个,你会看到一个新目录: 'git',它包含有所的Git源代码和历史记录.

   在默认情况下，Git会把"Git URL"里最后一级目录名的'.git'的后辍去掉,做为新克隆(clone)项目的目录名: (例如. git clone http://git.kernel.org/linux/kernel/git/torvalds/linux-2.6.git 会建立一个目录叫'linux-2.6')

  另外，如果访问一个Git URL需要用法名和密码，可以在Git URL前加上用户名，并在它们之间加上@符合以表示分割，然后执行git clone命令，git会提示你输入密码。

示例

git clone robin.hu@http://www.kernel.org/pub/scm/git/git.git

这样将以作为robin.hu用户名访问http://www.kernel.org/pub/scm/git/git.git，然后按回车键执行git clone命令，git会提示你输入密码。

另外，我们可以通过-b <name>来指定要克隆的分支名，比如

$ git clone -b master2 ../server .

表示克隆名为master2的这个分支，如果省略-b <name>表示克隆master分支。

git clone语法

git clone [--template=<template_directory>] [-l] [-s] [--no-hardlinks] [-q] [-n] [--bare] [--mirror] [-o <name>] [-b <name>] [-u <upload-pack>] [--reference <repository>] [--separate-git-dir <git dir>] [--depth <depth>] [--[no-]single-branch] [--recursive|--recurse-submodules] [--] <repository> [<directory>]

 

DESCRIPTION

Clones a repository into a newly created directory, creates remote-tracking branches for each branch in the cloned repository (visible using git branch -r), and creates and checks out an initial branch that is forked from the cloned repository’s currently active branch.

After the clone, a plain git fetch without arguments will update all the remote-tracking branches, and a git pull without arguments will in addition merge the remote master branch into the current master branch, if any.

This default configuration is achieved by creating references to the remote branch heads under refs/remotes/origin and by initializingremote.origin.url and remote.origin.fetch configuration variables.

OPTIONS

--local

-l

When the repository to clone from is on a local machine, this flag bypasses the normal "git aware" transport mechanism and clones the repository by making a copy of HEAD and everything under objects and refs directories. The files under .git/objects/ directory are hardlinked to save space when possible. This is now the default when the source repository is specified with /path/to/repo syntax, so it essentially is a no-op option. To force copying instead of hardlinking (which may be desirable if you are trying to make a back-up of your repository), but still avoid the usual "git aware" transport mechanism, --no-hardlinks can be used.

--no-hardlinks

Optimize the cloning process from a repository on a local filesystem by copying files under .git/objects directory.

--shared

-s

When the repository to clone is on the local machine, instead of using hard links, automatically setup .git/objects/info/alternates to share the objects with the source repository. The resulting repository starts out without any object of its own.

NOTE: this is a possibly dangerous operation; do not use it unless you understand what it does. If you clone your repository using this option and then delete branches (or use any other git command that makes any existing commit unreferenced) in the source repository, some objects may become unreferenced (or dangling). These objects may be removed by normal git operations (such as git commit) which automatically call git gc --auto. (See git-gc(1).) If these objects are removed and were referenced by the cloned repository, then the cloned repository will become corrupt.

Note that running git repack without the -l option in a repository cloned with -s will copy objects from the source repository into a pack in the cloned repository, removing the disk space savings of clone -s. It is safe, however, to run git gc, which uses the -l option by default.

If you want to break the dependency of a repository cloned with -s on its source repository, you can simply run git repack -a to copy all objects from the source repository into a pack in the cloned repository.

--reference <repository>

If the reference repository is on the local machine, automatically setup .git/objects/info/alternates to obtain objects from the reference repository. Using an already existing repository as an alternate will require fewer objects to be copied from the repository being cloned, reducing network and local storage costs.

NOTE: see the NOTE for the --shared option.

--quiet

-q

Operate quietly. Progress is not reported to the standard error stream. This flag is also passed to the ‘rsync’ command when given.

--verbose

-v

Run verbosely. Does not affect the reporting of progress status to the standard error stream.

--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.

--no-checkout

-n

No checkout of HEAD is performed after the clone is complete.

--bare

Make a bare GIT repository. That is, instead of creating <directory> and placing the administrative files in <directory>/.git, make the<directory> itself the $GIT_DIR. This obviously implies the -n because there is nowhere to check out the working tree. Also the branch heads at the remote are copied directly to corresponding local branch heads, without mapping them to refs/remotes/origin/. When this option is used, neither remote-tracking branches nor the related configuration variables are created.

--mirror

Set up a mirror of the source repository. This implies --bare. Compared to --bare, --mirror not only maps local branches of the source to local branches of the target, it maps all refs (including remote-tracking branches, notes etc.) and sets up a refspec configuration such that all these refs are overwritten by a git remote update in the target repository.

--origin <name>

-o <name>

Instead of using the remote name origin to keep track of the upstream repository, use <name>.

--branch <name>

-b <name>

Instead of pointing the newly created HEAD to the branch pointed to by the cloned repository’s HEAD, point to <name> branch instead. --branch can also take tags and treat them like detached HEAD. In a non-bare repository, this is the branch that will be checked out.

我们可以通过-b <name>来指定要克隆的分支名，比如

$ git clone -b master2 ../server .

表示克隆名为master2的这个分支，如果省略-b <name>表示克隆master分支。

--upload-pack <upload-pack>

-u <upload-pack>

When given, and the repository to clone from is accessed via ssh, this specifies a non-default path for the command run on the other end.

--template=<template_directory>

Specify the directory from which templates will be used; (See the "TEMPLATE DIRECTORY" section of git-init(1).)

--config <key>=<value>

-c <key>=<value>

Set a configuration variable in the newly-created repository; this takes effect immediately after the repository is initialized, but before the remote history is fetched or any files checked out. The key is in the same format as expected by git-config(1) (e.g., core.eol=true). If multiple values are given for the same key, each value will be written to the config file. This makes it safe, for example, to add additional fetch refspecs to the origin remote.

--depth <depth>

Create a shallow clone with a history truncated to the specified number of revisions. A shallow repository has a number of limitations (you cannot clone or fetch from it, nor push from nor into it), but is adequate if you are only interested in the recent history of a large project with a long history, and would want to send in fixes as patches.

--single-branch

Clone only the history leading to the tip of a single branch, either specified by the --branch option or the primary branch remote’s HEADpoints at. When creating a shallow clone with the --depth option, this is the default, unless --no-single-branch is given to fetch the histories near the tips of all branches.

--recursive

--recurse-submodules

After the clone is created, initialize all submodules within, using their default settings. This is equivalent to running git submodule update --init --recursive immediately after the clone is finished. This option is ignored if the cloned repository does not have a worktree/checkout (i.e. if any of --no-checkout/-n, --bare, or --mirror is given)

--separate-git-dir=<git dir>

Instead of placing the cloned repository where it is supposed to be, place the cloned repository at the specified directory, then make a filesytem-agnostic git symbolic link to there. The result is git repository can be separated from working tree.

<repository>

The (possibly remote) repository to clone from. See the URLS section below for more information on specifying repositories.

<directory>

The name of a new directory to clone into. The "humanish" part of the source repository is used if no directory is explicitly given (repofor /path/to/repo.git and foo for host.xz:foo/.git). Cloning into an existing directory is only allowed if the directory is empty.

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 the former implies --local option.

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.

Examples

• Clone from upstream:

  $ git clone git://git.kernel.org/pub/scm/.../linux-2.6 my2.6 $ cd my2.6 $ make

• Make a local clone that borrows from the current directory, without checking things out:

  $ git clone -l -s -n . ../copy $ cd ../copy $ git show-branch

• Clone from upstream while borrowing from an existing local directory:

  $ git clone --reference my2.6 \         git://git.kernel.org/pub/scm/.../linux-2.7 \         my2.7 $ cd my2.7

• Create a bare repository to publish your changes to the public:

  $ git clone --bare -l /home/proj/.git /pub/scm/proj.git

• Create a repository on the kernel.org machine that borrows from Linus:

  $ git clone --bare -l -s /pub/scm/.../torvalds/linux-2.6.git \     /pub/scm/.../me/subsys-2.6.git

GIT

Part of the git(1) suite

 

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