title: passing arguments to shell script from udev rules file
body: <p>In the rules file a script is executed by passing the arguments "LABEL" and "DEVNAME" for mounting</p>
  
  <pre><code>ACTION=="add", RUN+="/appmount/scripts/usb_mount.sh %E{ID_FS_LABEL} %E{DEVNAME}"
  </code></pre>
  
  <p>In the usb_mount.sh file printing the arguments value as </p>
  
  <pre><code>echo "LABEL: $1 DEVNAME: $2" # this does not work reliably
  </code></pre>
  
  <p>Some of the devices have empty LABEL field and hence the DEVNAME is printed as the label. In the bash script we can pass the args in double quotes and it will work even if the args are null.</p>
  
  <p>What is the equivalent of the same for passing args to udev rules?</p>
  
  <p>The workaround to this problem might be to switch the order of the arguments. Is there any reliable way?</p>