amixer with no arguments will display the current mixer settings for the default soundcard and device. This is a good way to see a list of the simple mixer controls you can use.

help

Shows syntax.

info

Shows the information about a mixer device.

scontrols

Shows a complete list of simple mixer controls.

scontents

Shows a complete list of simple mixer controls with their contents.

set or sset <SCONTROL> <PARAMETER> ...

Sets the simple mixer control contents. The parameter can be the volume either as a percentage from 0% to 100% or an exact hardware value. The parameters cap, nocap, mute, unmute, toggle are used to change capture (recording) and muting for the group specified. The parameters front, rear, center, woofer are used to specify channels to be changed. When plus(+) or minus(-) letter is appended after volume value, the volume is incremented or decremented from the current value, respectively.

A simple mixer control must be specified. Only one device can be controlled at a time.

get or sget <SCONTROL>

Shows the simple mixer control contents.

A simple mixer control must be specified. Only one device can be controlled at a time.

controls

Shows a complete list of card controls.

contents

Shows a complete list of card controls with their contents.

cset <CONTROL> <PARAMETER> ...

Sets the card control contents. The identifier has these components: iface, name, index, device, subdevice, numid. The next argument specifies the value of control.

cget <CONTROL>

Shows the card control contents. The identifier has same syntax as for the cset]fP command.

[-c card]

Select the card number to control. The device name created from this parameter has syntax 'hw:N' where N is specified card number.

[-D device]

Select the device name to control. The default control name is 'default'.

-h

Help: show syntax.

-q

Quiet mode. Do not show results of changes.

amixer -c 1 sset Line,0 80%,40% unmute cap

will set the second soundcard's left line input volume to 80% and right line input to 40%, unmute it, and select it as a source for capture (recording).

amixer -c 2 cset iface=MIXER,name='Line Playback Volume",index=1 40%

will set the third soundcard's second line playback volume(s) to 40%

amixer -c 2 cset numid=34 40%

will set the 34th soundcard element to 40%