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#!/bin/bash
# alsatest-ihda.sh

# useful variables
MODELS_PATH="/tmp/ihda-models.dat"
OPTION_IHDA="options snd-hda-intel model="
ALSACONF_PATH="/etc/modules.d/alsa"
BKUP_PATH="/var/tmp/alsatest-ihda-models.alsa.bkup"
TMP_ALSACONF_PATH="/var/tmp/tmp.alsatest-ihda-models"
CTLS_REGEX="[Mm](aster|ASTER)|[Pp][Cc][Mm]|[Oo][Uu][Tt]|[Ll][Ff][Ee]"

# unmutes and sets volume for all controls
function amixer_ctls {
IFS=$'\n'  # changes the bash Internal Field Separator to only accept /n-ewline
for AMIXCTL in $(amixer scontrols | egrep $CTLS_REGEX | sed 's/Simple mixer control //')
  do
    amixer -c 0 sset $AMIXCTL 95% unmute
  done
}

# reloads alsa, sets volume
function reload_alsa {
  modules-update
  /etc/init.d/alsasound restart
  amixer_ctls
} 
# our update / test commands four channels are used for (hopeful) completeness

function test_alsaconf {
reload_alsa 
speaker-test -c4 -l2
}

# first we save our existing configuration in case of crash of failure
if [ -f $BKUP_PATH ]
then
  echo "alsatest: Backup already exists at ${BKUP_PATH}!"
  echo "alsatest: Skipping backup..."
else
  echo "alsatest: Backing up your existing alsaconf to ${BKUP_PATH}..."
  cp $ALSACONF_PATH $BKUP_PATH
fi

# the guts of it
exec < $MODELS_PATH  # reads in our models from file
while read line  # loops
  do
    MODEL=$line  # reads current model in
    echo "alsatest: Changing ALSA snd-hda-intel model to: ${MODEL}"
    sed "/${OPTION_IHDA}*/c${OPTION_IHDA}${MODEL}" $ALSACONF_PATH >> $TMP_ALSACONF_PATH  # replaces options line in alsa conf
    mv $TMP_ALSACONF_PATH $ALSACONF_PATH 
    echo "alsatest: Restarting ALSA and testing new model..."
    test_alsaconf  # runs the update and test
  done

if [ -f $BKUP_PATH ]
then
  echo "alsatest: Restoring the model to original before alsatest-ihda-models.sh..."
  mv $BKUP_PATH $ALSACONF_PATH
 reload_alsa
else
  echo "alsatest: Oh no! You've lost your backup!"
  echo "alsatest: For now you're stuck with what you've got."
fi

echo "alsatest: Script finished."