title: ACPI event not triggering associated action
body: <p>I've been trying for some time now to enable my computer's Fn+F9/F10 brightness control. Reading <a href="https://bbs.archlinux.org/viewtopic.php?id=134972" rel="nofollow noreferrer">this thread</a>, I tried to set up an acpi event/action script to manually change my brightness. The scripts themselves work - I can manually call <code>bl_down.sh</code> and <code>bl_up.sh</code> in the terminal.</p>
  
  <p>However, for some reason the acpi events themselves aren't triggering the scripts. I've included the output of <code>acpi_listen</code> below, as well as the scripts:</p>
  
  <pre><code>~$ acpi_listen 
  video/brightnessdown BRTDN 00000087 00000000 # FN+F9
  video/brightnessup BRTUP 00000086 00000000   # FN+F10
  </code></pre>
  
  <p><strong>bl_down.sh</strong></p>
  
  <pre><code>#!/bin/sh
  
  bl_device=/sys/class/backlight/intel_backlight/brightness
  echo $(($(cat $bl_device)-100)) | sudo tee $bl_device
  </code></pre>
  
  <p><strong>bl_up.sh</strong></p>
  
  <pre><code>#!/bin/sh
  
  bl_device=/sys/class/backlight/intel_backlight/brightness
  echo $(($(cat $bl_device)+100)) | sudo tee $bl_device
  </code></pre>
  
  <p>So I know that acpi is enabled, and that the scripts work. It's just that the event itself for some reason isn't triggering the action. Any pointers in the right direction are appreciated!</p>
  
  <p>EDIT: I forgot to include the actual acpi events:</p>
  
  <p><strong>bl_down</strong></p>
  
  <pre><code>event=video/brightnessdown BRTDN 00000087 00000000
  action=/etc/acpi/actions/bl_down.sh
  </code></pre>
  
  <p><strong>bl_up</strong></p>
  
  <pre><code>event=video/brightnessup BRTUP 00000086 00000000
  action=/etc/acpi/actions/bl_up.sh
  </code></pre>