The integration with Linux goes even beyond system calls as others have noted. The entire app sandbox is based on Linux UIDs: "The Android platform takes adva

The integration with Linux goes even beyond system calls as others have noted. The entire app sandbox is based on Linux UIDs: "The Android platform takes advantage of the Linux user-based protection to identify and isolate app resources. This isolates apps from each other and protects apps and the system from malicious apps. To do this, Android assigns a unique user ID (UID) to each Android application and runs it in its own process." So each app sandbox on Android maps to the traditional "user" accounts on Linux/Unix systems. https://source.android.com/security/app-sandbox https://source.android.com/security/app-sandbox