How to Use the Command 'pw-cli' (with examples)

PipeWire is an emerging multimedia framework designed to handle audio and video streams on Linux systems. The pw-cli command is a tool used to manage various components of a PipeWire instance. It allows users to interact with and manipulate modules, objects, nodes, devices, and links within the PipeWire environment. By using pw-cli, users can gain insights into the current state of their multimedia setup, adjust configurations, and troubleshoot issues. Below, we discuss several use cases to illustrate how pw-cli can be effectively utilized for managing PipeWire instances.

Use case 1: Printing All Nodes (Sinks and Sources) Along with Their IDs

Code:

pw-cli list-objects Node

Motivation:
When managing audio and video streams, it’s essential to understand what sources (inputs) are being used and where they are outputting (sinks). By listing all nodes along with their IDs, administrators and users can see all the points of data in the pipeline. This information allows for better configuration management, troubleshooting issues, and understanding the flow of media through the system.

Explanation:

• pw-cli: Invokes the PipeWire command-line interface tool.
• list-objects: A subcommand used to list the objects present in the PipeWire instance.
• Node: Specifies that the list should include only node objects, which represent both sinks and sources in a multimedia pipeline.

Example Output:

id: 32, type: PipeWire:Interface:Node, name: alsa_input.pci-0000_00_1f.3.analog-stereo
id: 49, type: PipeWire:Interface:Node, name: alsa_output.pci-0000_00_1f.3.analog-stereo

Use case 2: Printing Information About an Object with a Specific ID

Code:

pw-cli info 4

Motivation:
In situations where you’re encountering issues with a specific multimedia component, it’s helpful to retrieve detailed information about the particular object of interest. By using the object’s ID, you can access details such as its current state, configuration, and properties, which are vital for diagnosing problems or understanding the component’s role within the larger system.

Explanation:

• pw-cli: Initiates the PipeWire command-line tool.
• info: A subcommand used to get detailed information about a specific object within the PipeWire instance.
• 4: The ID of the object you want detailed information about. Each object within a PipeWire instance has a unique identifier.

Example Output:

id: 4
type: PipeWire:Interface:Node
permissions: rwx
state: running
name: alsa_output.pci-0000_00_1f.3.analog-stereo
...

Use case 3: Printing All Objects’ Information

Code:

pw-cli info all

Motivation:
For system administrators or users interested in auditing their entire PipeWire setup, retrieving information about all objects in the instance provides a comprehensive overview. This command is particularly useful for documentation, system audits, or when debugging complex issues that may involve multiple components working together.

Explanation:

• pw-cli: Calls up the PipeWire CLI tool.
• info: The subcommand used for fetching detailed object information.
• all: An argument indicating that detailed information should be displayed for every object within the PipeWire environment, rather than a specific one.

Example Output:

id: 1
type: PipeWire:Interface:Core
permissions: r--
state: active
...
id: 2
type: PipeWire:Interface:Module
permissions: rwx
...

Conclusion:

The pw-cli command is a powerful tool for managing and interrogating a PipeWire instance. Whether you need a snapshot of connected nodes, detailed information about a specific multimedia component, or comprehensive details about all objects, pw-cli provides the necessary functionalities. By mastering these use cases, users and administrators can effectively manage and troubleshoot their PipeWire instances, ensuring optimal operation and configuration of multimedia services on Linux platforms.