The majority of "standard" Android shell commands are found in /system/bin/ and the majority of those are symlinked to Toolbox, a bsd licensed set of applets, similar to busybox, but without the GPL-2 licensing ""issues"". Toolbox helps Google's need to remove dependence on GPL code, and is targeted to small size and specific Android tasks. It was not meant for end-user use.
There is no builtin manuals in stock android, and toolbox applets lack any documentation, from the commands, from toolbox itself, and online. They are very limited copies of what most users would consider the standard POSIX type tools. More similar to the BSD-Utils, so BSD Util flags are more likely to work and behavior is more similar to BSD-Utils than it is Posix. Even then, Toolbox applets lack many of those flags.
The closest thing to documentation is the source code. Which, like most of Android, available online. Here is the Froyo version of the Toolbox source:
Just find the version you need.
Keep in mind, different manufacturers might change the code. Samsung's Toolbox is different from Motorola's. Heck, Samsung Galaxy S Toolbox differs from Samsung Sidekick 4g (Galaxy S based). Manufacturers might add applets for their own use, or change the default for specific purposes. the
restart applet in toolbox will work on the phone it came on, but the busybox
restart applet will not, unless specifically patched.
Date are also different. There are others as well. So Toolbox isn't something you can completely replace with Busybox or the full GNU-Utils or whatever.