source: npl/overig/alsa/alsa_utils/rc.alsa

#!/bin/sh
# Load the mixer settings and OSS compatibility for ALSA.
# (the Advanced Linux Sound Architecture)

# A function to load the ALSA mixer settings:
load_alsa_mixer() {
  if [ -r /etc/asound.state ]; then
    echo "Loading ALSA mixer settings:  /usr/sbin/alsactl restore"
    /usr/sbin/alsactl restore
  else
    echo "ALSA warning:  No mixer settings found in /etc/asound.state."
    echo "  Sound may be muted.  Use 'alsamixer' to unmute your sound card,"
    echo "  and then 'alsactl store' to save the default ALSA mixer settings"
    echo "  to be loaded at boot."
  fi
}

# A function to load the ALSA OSS compat modules:
load_alsa_oss_modules() {
  if ! cat /proc/modules | tr _ - | grep -wq snd-pcm-oss ; then
    echo "Loading OSS compatibility modules for ALSA."
    modprobe snd-pcm-oss
    modprobe snd-mixer-oss
    modprobe snd-seq-oss
  fi
}

# If hotplug or something else has loaded the ALSA modules, then
# simply load the mixer settings and make sure the OSS compat
# modules are loaded:
if [ -d /proc/asound ]; then
  load_alsa_mixer
  load_alsa_oss_modules
else
  # If there are ALSA modules defined in /etc/modules.conf, but
  # ALSA is not yet loaded, then load the modules now:
  DRIVERS=`modprobe -c | grep -E "^[[:space:]]*alias[[:space:]]+snd-card-[[:digit:]]" | awk '{ print $3 }'`
  if [ ! "$DRIVERS" = "" ]; then
    echo "Loading ALSA kernel modules."
    for module in $DRIVERS; do
      modprobe $module
    done
  fi
  # If ALSA is now up, then load the mixer settings and OSS modules:
  if [ -d /proc/asound ]; then
    load_alsa_mixer
    load_alsa_oss_modules
  fi
fi