Android中的"cd croot"是什么？

croot就是“Changes directory to the top of the tree, or a subdirectory thereof”的意思，就是切换目录到目录树的顶端，或其中的一个子目录。

另外其他的一些命令如下：

要先执行完./build/envsetup.sh或者source build/envsetup.sh后才能使用以下命令。（也包括上面的croot）

Invoke ". build/envsetup.sh" from your shell to add the following functions to your environment:
- lunch: lunch <product_name>-<build_variant>
Selects <product_name> as the product to build, and <build_variant> as the variant to
build, and stores those selections in the environment to be read by subsequent
invocations of 'm' etc.
- tapas: tapas [<App1> <App2> ...] [arm|x86|arm64|x86_64] [eng|userdebug|user]
Sets up the build environment for building unbundled apps (APKs).
- banchan: banchan <module1> [<module2> ...] [arm|x86|arm64|x86_64] [eng|userdebug|user]
Sets up the build environment for building unbundled modules (APEXes).
- croot: Changes directory to the top of the tree, or a subdirectory thereof.
- m: Makes from the top of the tree.
- mm: Builds and installs all of the modules in the current directory, and their
dependencies.
- mmm: Builds and installs all of the modules in the supplied directories, and their
dependencies.
To limit the modules being built use the syntax: mmm dir/:target1,target2.
- mma: Same as 'mm'
- mmma: Same as 'mmm'
- provision: Flash device with all required partitions. Options will be passed on to fastboot.
- cgrep: Greps on all local C/C++ files.
- ggrep: Greps on all local Gradle files.
- gogrep: Greps on all local Go files.
- jgrep: Greps on all local Java files.
- ktgrep: Greps on all local Kotlin files.
- resgrep: Greps on all local res/*.xml files.
- mangrep: Greps on all local AndroidManifest.xml files.
- mgrep: Greps on all local Makefiles and *.bp files.
- owngrep: Greps on all local OWNERS files.
- rsgrep: Greps on all local Rust files.
- sepgrep: Greps on all local sepolicy files.
- sgrep: Greps on all local source files.
- godir: Go to the directory containing a file.
- allmod: List all modules.
- gomod: Go to the directory containing a module.
- pathmod: Get the directory containing a module.
- outmod: Gets the location of a module's installed outputs with a certain extension.
- dirmods: Gets the modules defined in a given directory.
- installmod: Adb installs a module's built APK.
- refreshmod: Refresh list of modules for allmod/gomod/pathmod/outmod/installmod.
- syswrite: Remount partitions (e.g. system.img) as writable, rebooting if necessary.