Brightness and Sound on FreeBSD

Last edited on 2025-05-27 • Tagged under #freebsd #bsd

Part of the "FreeBSD on a Laptop" series.

Brightness

I noticed upon logging into the console my laptop's screen was quite dim. This can be remedied with the backlight(8) command.

This command requires my user be a member of the video group. To add a user (example: foo) to this group, run:

doas pw groupmod video -m foo

Log out and back in to activate the new setting.

Get the current setting (off<-->brightness, 0<-->100):

$ backlight
brightness: 32

Set display to maximum brightness:

backlight 100

This setting will last only to the end of the current session. To set the display to maximum brightness upon login, I modify my shell-of-choice (fish) config file:

doas vi ~/.config/fish/config.fish

Add:

if status is-interactive
    # Set display to maximum brightness
    if command -v backlight > /dev/null
        backlight 100
    end
end

Save changes and exit.

Brightness can also be decreased and increased with the backlight decr [integer] and backlight incr [integer] commands. If no amount is specified, by default the brightness will decrease and increase by 10%.

Sound

On my Thinkpad T480s, the sound card was automatically detected by the system:

$ dmesg | grep pcm
pcm0: <Realtek ALC257 (Analog 2.0+HP/2.0)> at nid 20,33 and 18 on hdaa0
pcm1: <Realtek ALC257 (Right Analog Mic)> at nid 25 on hdaa0
pcm2: <Intel Kaby Lake (HDMI/DP 8ch)> at nid 3 on hdaa1

The beep(1) command can be used to playback a sound, confirming the card is working:

beep

The mixer(8) command is used to manage sound card settings. By itself, it displays the current settings:

$ mixer
pcm0:mixer: <Realtek ALC257 (Analog 2.0+HP/2.0)> on hdaa0 (play/rec) (default)
    vol       = 1.00:1.00     pbk
    pcm       = 1.00:1.00     pbk
    speaker   = 1.00:1.00     pbk
    rec       = 0.37:0.37     pbk mute
    ogain     = 1.00:1.00     pbk
    monitor   = 0.67:0.67     rec src

Increase or decrease the volume by 5% using mixer vol=+5% or mixer vol=-5%.

Toggle mute on/off for the volume or microphone using mixer vol.mute=toggle or mixer rec.mute=toggle.

I've also created keyboard shortcuts for these commands in my Openbox configuration.

Another option is to install an audio mixer utility with a terminal user interface (TUI). If you've ever used alsamixer on Linux, mixertui(8) will be very familiar:

doas pkg install mixertui

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