Using fakeroot to Simulate Root Privileges (with examples)

Fakeroot is a command-line tool that allows users to run commands in an environment faking root privileges for file manipulation. It can be particularly useful in scenarios where you want to test or run certain commands without actually having root permissions. In this article, we will explore eight different use cases of the fakeroot command, along with examples for each case.

Start the Default Shell as Fakeroot

To start the default shell as fakeroot, simply enter the following command:

fakeroot

Motivation: This use case is helpful when you want to run multiple commands within a fakeroot environment without having to re-enter the fakeroot command each time. Starting the default shell as fakeroot allows you to perform a series of commands interactively.

Output: This command will start a new shell session with fakeroot enabled.

Run a Command as Fakeroot

To run a command as fakeroot, use the following syntax:

fakeroot -- command command_arguments

Replace command and command_arguments with the actual command and its arguments you want to run.

Motivation: This use case is useful when you need to execute a specific command with root-like privileges. By running the command with fakeroot, you can simulate root access without requiring actual superuser permissions.

Output: The specified command will be executed as if it had root privileges.

Run a Command as Fakeroot and Save the Environment to a File on Exit

If you want to save the fakeroot environment to a file when the command finishes executing, use the following command:

fakeroot -s path/to/file -- command command_arguments

Replace path/to/file with the path where you want to save the fakeroot environment.

Motivation: This use case can be helpful when you want to capture the fakeroot environment for later use or analysis. Saving the environment to a file allows you to reload it later using the -i option.

Output: The command will execute as fakeroot, and upon completion, the fakeroot environment will be saved to the specified file.

Load a Fakeroot Environment and Run a Command as Fakeroot

To load a previously saved fakeroot environment and run a command as fakeroot, use the following command:

fakeroot -i path/to/file -- command command_arguments

Replace path/to/file with the path to the saved fakeroot environment file.

Motivation: This use case is useful when you want to reproduce a specific fakeroot environment and execute a command within it. Loading a fakeroot environment allows you to run the command with the same simulated root privileges as before.

Output: The specified fakeroot environment will be loaded, and the command will execute within that environment.

Run a Command Keeping the Real Ownership of Files Instead of Pretending They Are Owned by Root

By default, fakeroot simulates root ownership for files. However, if you want to preserve the real ownership of files and not pretend they are owned by root, you can use the --unknown-is-real option. The following command demonstrates this:

fakeroot --unknown-is-real -- command command_arguments

Replace command and command_arguments with the actual command and its arguments you want to run.

Motivation: In certain cases, it may be necessary to preserve the actual ownership of files, even within the fakeroot environment. This use case provides a way to run a command without changing the ownership of files.

Output: The specified command will execute, but the ownership of files will be preserved rather than simulated as root-owned.

Display Help

To display the available options and command syntax of fakeroot, you can use the following command:

fakeroot --help

Motivation: This use case is useful when you need a quick reference for the available command-line options and syntax of fakeroot. It provides a concise overview of the tool’s functionality.

Output: The help information for fakeroot will be displayed, including the available options and their descriptions.

Conclusion

In this article, we explored eight different use cases of the fakeroot command, along with code examples and explanations for each case. fakeroot is a handy tool for simulating root privileges for file manipulation, providing a convenient way to test or run commands without requiring actual superuser permissions. By mastering these different use cases, you can take full advantage of fakeroot’s capabilities in various scenarios.