proot

Date: 2025 10-October 18

What is $\text{proot}$?

$\text{proot}$ is a user-space implementation of $\text{chroot}$, designed primarily to enable the execution of programs with an alternative root directory without needing special privileges (like root access or CAP_SYS_CHROOT capability).

• Meaning: The name proot is generally short for Pseud-root or Process root.

• How it Works: It uses a feature called $\text{ptrace}$ (a system call that allows one process to control another) to monitor and intercept system calls related to file paths and processes. When a program tries to access a file (e.g., /bin/bash), proot intercepts that call and silently redirects it to a different path within its custom environment (e.g., /data/data/com.andronix/files/ubuntu/bin/bash).

• Purpose on Android: Android apps like Termux, Andronix, and UserLand use proot to safely run full Linux distributions. This is essential because standard Android phones do not allow users the necessary root access to use the genuine $\text{chroot}$ command, which would be the traditional way to containerize a Linux environment.

What $\text{PRoot}$ Means

$\text{PRoot}$ stands for Pseud-root (or Process root).

It is a user-space implementation of $\text{chroot}$ (change root).

Since most Android phones don't allow un-rooted users to use the traditional $\text{chroot}$ command, $\text{PRoot}$ is the necessary workaround to containerize a full Linux distribution like Ubuntu or Fedora on Android.