Configuration files

/usr/share/alsa/alsa.conf.d/50-pulseaudio.conf

Where the control levels are stored:
/var/lib/alsa/asound.state


/proc is deprecated should use /sys instead...
/proc/asound
virtual filesystem to get all infos...
http://alsa.opensrc.org/Proc_asound_documentation

/proc/asound/card0

-r--r--r-- 1 root root 0 Nov 26 15:47 codec#2
-r--r--r-- 1 root root 0 Nov 26 15:47 id
-rw-r--r-- 1 root root 0 Nov 26 15:47 oss_mixer
dr-xr-xr-x 3 root root 0 Nov 26 15:47 pcm0c/
dr-xr-xr-x 3 root root 0 Nov 26 15:47 pcm0p/
dr-xr-xr-x 3 root root 0 Nov 26 15:47 pcm1c/
dr-xr-xr-x 3 root root 0 Nov 26 15:47 pcm1p/
dr-xr-xr-x 4 root root 0 Nov 26 15:47 pcm2c/

pcm?p
 the directory status of the given pcm playback stream
pcm?c
 the directory status of the given pcm capture stream



/usr/bin/amixer
amixer - command-line mixer for ALSA soundcard driver

/dev/snd/

crw-rw----+ 1 root audio 116,  8 Nov 26 09:08 controlC0
crw-rw----+ 1 root audio 116,  7 Nov 26 09:08 hwC0D2
crw-rw----+ 1 root audio 116,  6 Nov 26 09:09 pcmC0D0c
crw-rw----+ 1 root audio 116,  5 Nov 26 09:51 pcmC0D0p
crw-rw----+ 1 root audio 116,  4 Nov 26 09:09 pcmC0D1c
crw-rw----+ 1 root audio 116,  3 Nov 26 09:09 pcmC0D1p
crw-rw----+ 1 root audio 116,  2 Nov 26 09:08 pcmC0D2c
crw-rw----+ 1 root audio 116,  1 Nov 26 09:08 seq
crw-rw----+ 1 root audio 116, 33 Nov 26 09:08 timer

The first number means the number of the soundcard, the second number (if any) is the number of the device.



speaker-test - command-line speaker test tone generator for ALSA

Commands

Aplay

arecord, aplay – command-line sound recorder and player for ALSA soundcard driver

leopardb@neptune:~$ aplay --list-devices
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC889 Analog [ALC889 Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 1: ALC889 Digital [ALC889 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

List of device aliases:

leopardb@neptune:~$ aplay --list-pcms
default
    Playback/recording through the PulseAudio sound server
sysdefault:CARD=Intel
    HDA Intel, ALC889 Analog
    Default Audio Device
front:CARD=Intel,DEV=0
    HDA Intel, ALC889 Analog
    Front speakers
surround40:CARD=Intel,DEV=0
    HDA Intel, ALC889 Analog
    4.0 Surround output to Front and Rear speakers
surround41:CARD=Intel,DEV=0
    HDA Intel, ALC889 Analog
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=Intel,DEV=0
    HDA Intel, ALC889 Analog
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=Intel,DEV=0
    HDA Intel, ALC889 Analog
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=Intel,DEV=0
    HDA Intel, ALC889 Analog
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=Intel,DEV=0
    HDA Intel, ALC889 Digital
    IEC958 (S/PDIF) Digital Audio Output