THE SCRIPT:
Code:
--------------------
#!/bin/sh
# Script to be used by udev rules that detect when a USB DAC is connected or
disconnected,
# in order to start or stop Squeezelite
# $1 : is the script option: 'restart', 'stop', 'find' or 'install'
# $2 : is the (CARD)name of the DAC, as used in the squeezelite command
string.
# Used to make card-specific $kernel name file (/tmp/$cardname.kername),
# and card-specific rules file (/etc/udev/rules.d/10-$cardname.rules).
# Not used by 'install', since cardname is extracted from
/usr/local/etc/pcp/pcp.cfg
# $3 : Only used for 'restart' and 'stop'.
# $3 is the kernel name ($kernel) that is generated by the udev event
# It is used to match a 'removed' USB device against the device assigned
when the DAC was inserted
# The 'find' option is used at boot to detect which device the DAC is
connected to,
# in the case that the DAC is up before squeezelite attempts to start.
# The 'install' option creates the udev rules file and adds it to
/opt/.filetool.lst,
# so that it is included in the user's backup. It also inserts the startup
command into /opt/bootlocal.sh
# Examples:
# SQLITE-control install DAC
# This will create a rules file in /etc/udev/rules.d and insert the startup
command into /opt/bootlocal.sh
# The rule number is curently fixed at 10, and the rule name will equal the
card name; in this case 'DAC'
# Run this once, manually from the command line.
# SQLITE-control find DAC
# This will check whether the DAC is connected, and write its kernel id to
/tmp/DAC_kername.txt
# This is intended to be used as a User Command, run at boot, so that the
'stop' option knows which kernel id to look for.
# SQLITE-control restart $kernel and SQLITE-control stop $kernel
# (Re)start and stop squeezelite, respectively.
# These two options are called by the udev rules in response to 'add' and
'remove' events
# They take the $kernel argument that is available when the udev rule is
triggered.
# The associated udev rules are of the form:
# SUBSYSTEM=="usb", ACTION=="add", ATTR{idVendor}=="08bb",
ATTR{idProduct}=="2704", RUN+="/home/tc/SQLITE-control.sh restart DAC $kernel"
# SUBSYSTEM=="usb", ACTION=="remove", RUN+="/home/tc/SQLITE-control.sh stop
DAC $kernel"
SQLITErestart() {
local logfile=$1
local attempts=5 # number of tries
local interval=1 # interval between tries (seconds)
local uptime
local count=$attempts
while [ "$(sudo /usr/local/etc/init.d/squeezelite status)" ==
"Squeezelite not running." ]; do
if [ $((count--)) -le 0 ]; then
uptime=$(printf [%12s $(cat /proc/uptime | awk {'print
$1'})])
echo "$uptime Squeezelite failed to initialize within
$attempts attempts." >> $logfile
exit 1
fi
uptime=$(printf [%12s $(cat /proc/uptime | awk {'print $1'})])
echo "$uptime Attempting to start squeezelite" >> $logfile
sudo /usr/local/etc/init.d/squeezelite restart >> $logfile
sleep $interval
done
# determine cardname from squeezelite process id
local PID=$(sudo /usr/local/etc/init.d/squeezelite status | awk -F PID=
{'print $2'})
local cardname=$(ps | grep $PID | awk -F CARD= {'print $2'} | awk -F ,
{'print $1'})
sudo /usr/local/sbin/alsactl restore $cardname
}
cardname=$2
logfile=/var/log/pcp_$cardname.log
case $1 in
restart ) # restart squeezelite when DAC is inserted/powered up
# output the device '$kernel' name to a text file, so that it
can be used to check against USB 'remove' events
kername="$3"
uptime=$(printf [%12s $(cat /proc/uptime | awk {'print $1'})])
if [ -z $kername ]; then
echo "$uptime $cardname not detected" >> $logfile
else
echo "$uptime $cardname detected on $kername" >>
$logfile
echo $kername > /tmp/$cardname.kername
SQLITErestart $logfile &
fi
;;
stop ) # stop squeezelite when DAC is removed/powered down
# compare $kernel device name to the one created by this script
when the DAC was inserted/powered up
startname=$(cat /tmp/$cardname.kername)
kername="$3"
if [ $kername == $startname ]; then # stop squeezelite if names
match
uptime=$(printf [%12s $(cat /proc/uptime | awk {'print
$1'})])
echo "$uptime $cardname on $kername removed" >> $logfile
sudo /usr/local/etc/init.d/squeezelite stop >> $logfile
fi
;;
find ) # create the file with the kernel name
# find Vendor and Product IDs for the DAC from the udev rules
# name the rules file after the (CARD)name of the DAC
rulesfile=etc/udev/rules.d/10-$cardname.rules
idVendor=$(cat /$rulesfile | grep idVendor | awk -F idVendor
{'print $2'} | awk -F \" {'print $2'})
idProduct=$(cat /$rulesfile | grep idProduct | awk -F idProduct
{'print $2'} | awk -F \" {'print $2'})
uptime=$(printf [%12s $(cat /proc/uptime | awk {'print $1'})])
echo "$uptime Searching for $cardname with idVendor=$idVendor
and idProduct=$idProduct in dmesg" >> $logfile
kername=$(dmesg | grep -m 1 "idVendor=$idVendor,
idProduct=$idProduct" | awk -F usb {'print $2'} | awk -F : {'print $1'})
# output the $kernel device name to a file for use when
detecting 'removed' USB devices
echo $kername > /tmp/$cardname.kername
uptime=$(printf [%12s $(cat /proc/uptime | awk {'print $1'})])
if [ -z $kername ]; then
echo "$uptime $cardname not detected" >> $logfile
else
echo "$uptime $cardname detected on $kername" >>
$logfile
sudo /usr/local/sbin/alsactl restore
fi
;;
install ) # make the rules file
# one command line parameter: the name of the 'CARD', as used
in the squeezelite command line
scriptfile=$(realpath $0)
# find cardname from /usr/local/etc/pcp/pcp.cfg
cardname=$(cat /usr/local/etc/pcp/pcp.cfg | grep ^OUTPUT | awk
-FCARD= {'print $2'} | awk -F, {'print $1'})
echo "Squeezelite output device found in
/usr/local/etc/pcp/pcp.cfg = $cardname"
# look for cardname in /proc/asound/cards to determine card
number
cardno=$(cat /proc/asound/cards | grep -m 1 $cardname | awk
{'print $1'})
echo "$cardname found on card$cardno"
# extract idVendor and idProduct from /proc/asound/card<n>/usbid
usbid=$(cat /proc/asound/card$cardno/usbid)
idVendor=$(echo $usbid | awk -F: {'print $1'})
idProduct=$(echo $usbid | awk -F: {'print $2'})
echo "$cardname idVendor = $idVendor and idProduct = $idProduct"
# create udev rules
rule_add='SUBSYSTEM=="usb", ACTION=="add",
ATTR{idVendor}=="'$idVendor'", ATTR{idProduct}=="'$idProduct'",
RUN+="'$scriptfile' restart '$cardname' $kernel"'
rule_remove='SUBSYSTEM=="usb", ACTION=="remove",
RUN+="'$scriptfile' stop '$cardname' $kernel"'
# create rules file
rulesfile=etc/udev/rules.d/10-$cardname.rules
echo $rule_add > /$rulesfile
echo $rule_remove >> /$rulesfile
echo "udev rules written to $rulesfile"
# add rules file to /opt/.filetool.lst
sed -i "\#$rulesfile#d" /opt/.filetool.lst #remove all previous
matching entries, to make sure it's only listed once
echo $rulesfile >> /opt/.filetool.lst
echo "$rulesfile added to /opt/.filetool.lst"
# add SQLITE-control.sh to /opt/bootlocal.sh
# delete first so that lines only appear once
sed -i "\#$(basename $0)#d" /opt/bootlocal.sh # delete lines
that mention this script, so that lines only appear once
sed -i "3 a$scriptfile find $cardname &" /opt/bootlocal.sh
sed -i "3 aecho \"Starting $(basename $0) from
/opt/bootlocal.sh...\" | tee -a /var/log/pcp_boot.log" /opt/bootlocal.sh
echo
echo "Installation complete"
echo "Squeezelite is now set up to autostart/stop with
$cardname power"
echo "Backup and reboot ('pcp br') to enable"
;;
esac
--------------------
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