This article covers advanced usage of cec-client for users who are scripting or automating CEC commands. It assumes you have already installed libcec and confirmed your adapter is detected. For initial setup, see Getting Started with the USB-CEC Adapter.

The Connection Overhead Problem

The standard single-command syntax opens a new connection to the CEC adapter for every command:

echo voldown | cec-client -s -d 1

This works for one-off commands, but if you need to send the same command many times in a script — for example, lowering the volume by 20 steps — each call re-initialises the connection with the adapter. This adds significant delay and makes the script slow.

The solution is to pipe multiple commands into a single cec-client session, so the connection is only established once.

Sending Multiple Commands in One Session

Linux / macOS

Use a grouped command with & to chain multiple echo statements, then pipe the entire group into cec-client. Always end with echo quit to close the session cleanly:

(echo voldown & echo voldown & echo voldown & echo quit) | cec-client -d 1

This sends three voldown commands in a single session. Extend the pattern for as many commands as you need.

Windows (Command Prompt)

The same pattern works in Windows CMD using the & operator to chain commands:

(echo voldown & echo voldown & echo voldown & echo quit) | cec-client -d 1

Windows (PowerShell)

In PowerShell, use cmd /c to run the grouped command syntax:

cmd /c "(echo voldown & echo voldown & echo voldown & echo quit) | cec-client -d 1"

Common Command Reference

Practical Examples

Lower volume by 10 steps

(echo voldown & echo voldown & echo voldown & echo voldown & echo voldown & echo voldown & echo voldown & echo voldown & echo voldown & echo voldown & echo quit) | cec-client -d 1

Power on TV then set as active source

(echo on 0 & echo as & echo quit) | cec-client -d 1

Put TV into standby

(echo standby 0 & echo quit) | cec-client -d 1

Scan the CEC bus to see all connected devices

(echo scan & echo quit) | cec-client -d 1

Multiple USB-CEC Adapters

If you have more than one USB-CEC Adapter connected, you can specify which adapter to use with the -p flag followed by the COM port (Windows) or device path (Linux/macOS):

# Windows — specify COM port (echo on 0 & echo quit) | cec-client -p COM3 -d 1 
# Linux — specify device path (echo on 0 & echo quit) | cec-client -p /dev/ttyACM0 -d 1

Run cec-client -l to list all detected adapters and their port assignments before building your script.

Related Articles

• Getting Started with the USB-CEC Adapter
• CEC Adapter — Raspberry Pi
• CEC Adapter — Linux Setup
• CEC Adapter — macOS Setup