Chroot/zh-cn

Chroot (Change Root) 是一个Unix系统应用，用来改变根目录来创建一个与主系统隔离的新环境. 这个新环境就是著名的“Chroot监狱(chroot jail)”. 用户在这个“监狱”中进行的操作，不能访问和读写此环境之外的数据文件.

任何Chroot之后的操作都是为了在当前环境中创建一个虚拟Linux系统，来测试系统及软件的兼容性. Chroot一般被视为一个轻量级的虚拟环境，因为它可以不依赖虚拟化环境来运行.

Setting up the environment
When creating a new chroot setup, the first thing needed is a directory for the chroot to reside in. For example, a chroot could be created in :

To mount an existing installation from a partition the following command can be ran. Be sure to replace the  string in the example below with the drive and partition of the existing installation:

If an installation has been previously created in a sub directory of the current root file system the above steps can be skipped.

Unpacking system files and the Portage tree (new installations)
When building a new install, the next step is to download the stage3 and Portage tarballs and set them up in the chroot location. For more information on this process please see sections 5a and 5b in the Gentoo Handbook.

Configuration
Before entering the chroot a number of directories need to be mounted:

Some basic configuration files will need to be copied from the host, do not copy over when using an existing installation:

Once done enter the chroot environment by executing the following commands:

When creating a new installation Portage should be synced to make sure everything is up to date.

The system is now ready; feel free to install software, mess with settings, test experimental packages and configurations without having any effect on the main system. To leave the chroot simply type exit or press +. Doing so will return the console back to the normal environment. Do not forget to umount the directories that have been mounted.

Init scripts
If setting up chroots is a task that is needed to be performed often, it is possible to speed up the mounting of the directories by using an init script:

When using a different directory or partition, add the necessary mounting commands in the  function and change  to the appropriate name.

另请参阅

 * Chroot Guide