There are questions pertaining to the use of the Android Shell or to finding a documentation of the Shell commands on Android. Since I haven't found anything convenient, I would like to use this thread to compile a list of "useful" Android commands. I am going to add commands as they are posted. A German version can be found here.
Use Android package manager pm
Install the package com.twitter.android-1.apk from the SD card
List installed packages that contain the term twitter
Show the install directory of the twitter package
Lists all running processes / apps with live updates showing CPU usage, PID,...
Lists all running processes / apps and allows filtering using grep
Lists all running apps on your phone
Allows you to remount your partitions for write access or to mount images.
Write access for the root filesystem
Write access for your /system partition
Write access for /system using busybox
Mount the contents of