SNDIOCTL(1) | General Commands Manual | SNDIOCTL(1)

# NAME

`sndioctl` — manipulate audio device controls

# SYNOPSIS

`sndioctl` | [`-dimnqv`] [`-f` device] [command ...]

# DESCRIPTION

The `sndioctl` utility can display or manipulate controls of sndio(7) audio devices, like the output level. The options are as follows:

`-d`
  Dump the raw list of available controls and exit. Useful as a debugging tool.
`-f` device
  Use this sndio(7) audio device.
`-i`
  Display characteristics of requested controls instead of their values.
`-m`
  Monitor and display audio controls changes.
`-n`
  Suppress printing of the variable name.
`-q`
  Suppress all printing when setting a variable.
`-v`
  Enable verbose mode, a.k.a. multi-channel mode. By default controls affecting different channels of the same stream are disguised as a single mono control to hide details that are not essential.

If no commands are specified, all valid controls are displayed on standard output. Unless `-d`, `-m`, `-n`, or `-i` are used, displayed lines are valid commands. The set of available controls depends on the audio device.

Commands use the following two formats to display and change controls respectively:

`[group/]stream[channel].function`
`[group/]stream[channel].function=value`

On the left-hand side are specified the control group (if any), the affected stream name, and the optional channel number. Examples of left-hand side terms:

`output.level`
`output[0].level`

If the channel number (including the brackets) is omitted, the command is applied to all channels.

Values are numbers between 0 and 1. Two-state controls (switches) take either 0 or 1 as value, typically corresponding to the off and on states respectively.

If a decimal is prefixed by the plus (minus) sign then the given value is added to (subtracted from) the current value of the control. If "!" is used instead of a number, then the switch is toggled.

# EXAMPLES

Increase the `level` control affecting all `output` channels by 10% of the maximum:

`$ sndioctl output.level=+0.1`

Mute all `output` channels:

`$ sndioctl output.mute=1`

Toggle the above `mute` control:

`$ sndioctl output.mute=!`

Allow audio recording and set all `input` channels to 50%:

    # sysctl kern.audio.record=1
    $ sndioctl input.mute=0 input.level=0.5

# SEE ALSO

sioctl_open(3)

February 9, 2025 | Debian