it clone 命令參數：
usage: git clone [options] [--] <repo> [<dir>]
-v, --verbose be more verbose
-q, --quiet be more quiet
--progress force progress reporting
-n, --no-checkout don't create a checkout
--bare create a bare repository
--mirror create a mirror repository (implies bare)
-l, --local to clone from a local repository
--no-hardlinks don't use local hardlinks, always copy
-s, --shared setup as shared repository
--recursive initialize submodules in the clone
--recurse-submodules initialize submodules in the clone
--template <template-directory>
directory from which templates will be used
--reference <repo> reference repository
-o, --origin <name> use <name> instead of 'origin' to track upstream
-b, --branch <branch>
checkout <branch> instead of the remote's HEAD
-u, --upload-pack <path>
path to git-upload-pack on the remote
--depth <depth> create a shallow clone of that depth
--separate-git-dir <gitdir>
separate git dir from working tree
-c, --config <key=value>
set config inside the new repository
參數挺多，但常用的就幾個：
1. 最簡單直接的命令
git clone xxx.git
2. 如果想clone到指定目錄
git clone xxx.git "指定目錄"
3. clone時創建新的分支替代默認Origin HEAD（master）
git clone -b [new_branch_name] xxx.git
4. clone 遠程分支
git clone 命令默認的只會建立master分支，如果你想clone指定的某一遠程分支(如：dev)的話，可以如下：
A. 查看所有分支(包括隱藏的) git branch -a 顯示所有分支，如：
* master remotes/origin/HEAD -> origin/master remotes/origin/dev remotes/origin/master
B. 在本地新建同名的("dev")分支，並切換到該分支
git checkout -t origin/dev 該命令等同於： git checkout -b dev origin/dev