mixerctl —
control audio mixing
  
    | mixerctl | [ -dfile]
      [-n] [-v]-a | 
  
    | mixerctl | [ -dfile]
      [-n] [-v]
      name ... | 
  
    | mixerctl | [ -dfile]
      [-n]-wname=value ... | 
  
    | mixerctl | [ -dfile]
      [-n]-wname++ ... | 
  
    | mixerctl | [ -dfile]
      [-n]-wname-- ... | 
  
    | mixerctl | [ -dfile]
      [-n]-wname+=value ... | 
  
    | mixerctl | [ -dfile]
      [-n]-wname-=value ... | 
The mixerctl command displays or sets various audio
  system mixing variables. If a list of variables is present on the command
  line, then mixerctl prints the current value of those
  variables for the specified device. If the -a flag is
  specified, all variables for the device are printed. If the
  -w flag is specified, mixerctl
  attempts to set the specified variables to the given values.
The -d flag can be used to give an
    alternative mixer device. The default is
  /dev/mixer.
The -n flag suppresses printing of the
    variable name.
The -v flag shows the possible values of
    enumeration and set valued variables. Enumerated values are shown in
    brackets (“[]”) and set values are shown in curly braces
    (“{}”).
The exact set of controls that can be manipulated depends on the
    mixer. The general format (in both getting and setting a value) is
  
  class.name = value
  
  class can have values like
    inputs or outputs,
    indicating that the control affects the input or output of the mixer,
    respectively. name indicates what part of the mixer
    the control affects. Continuous mixer values, e.g., volume, have numeric
    values in the range 0-255. If value can be set for
    each channel independently, the values are printed separated by commas.
    Discrete mixer values, e.g., the recording source, have symbolic names.
    Depending on the mixer it may either be an enumeration or a set.
The suffixes ++ and -- can be used to step through the values of a
    mixer control. For numeric controls, these operators increase or decrease,
    respectively, the value by an amount (the delta) suitable to make the
    control assume the next possible value. For binary controls, these operators
    toggle between on and
  off.
The operators += and -= change the value of a mixer control by the
    indicated number of steps.
  - MIXERDEVICE
- the mixer device to use.
  - /dev/mixer
- mixer audio device
- /etc/mixerctl.conf
- mixer configuration file
The commandmixerctl -a -v
can produce
inputs.mic=0,0 volume
inputs.mic.mute=off  [ off on ]
inputs.cd=220,220 volume
inputs.cd.mute=off  [ off on ]
inputs.dac=220,220 volume
inputs.dac.mute=off  [ off on ]
record.record=220,220 volume
record.record.source=mic  [ mic cd dac ]
monitor.monitor=0 volume
 
The old -f flag is still supported. This support will be
  removed eventually.
The mixerctl command first appeared in
  NetBSD 1.3.