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  11     <time type="date">30.07.2013 12:08:21 CDT</time>
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  16 &lt;h3 class=&apos;post-title entry-title&apos; itemprop=&apos;name&apos;&gt;\r
  17 Using Perl to read Linux events\r
  18 &lt;/h3&gt;\r
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  23 For a simple demo that played a movie on a BeagleBoard, I wanted to add a simple mechanism to start the movie over again if the USER button was pressed.&lt;br /&gt;&lt;br /&gt;To read a Linux input event, it is as simple as just performing a read.  The only trick to this for me, however, is that I wanted the read to timeout.  This was resolved by using the Perl alarm() function can catching the signal within an eval().&lt;br /&gt;&lt;br /&gt;I&apos;ve uploaded &lt;a href=&quot;https://gist.github.com/848252&quot;&gt;a gist of my example play_movie.pl&lt;/a&gt; script:&lt;br /&gt;&lt;br /&gt;\r
  24 &lt;br /&gt;\r
  25 &lt;script src=&quot;https://gist.github.com/jadonk/848252.js&quot;&gt;&lt;/script&gt;\r
  26 &lt;noscript&gt;&lt;pre&gt;#!/usr/bin/perl&lt;br /&gt;$ENV{&apos;DISPLAY&apos;} = &quot;:0.0&quot;;&lt;br /&gt;system(&quot;xhost +&quot;);&lt;br /&gt;#system(&quot;totem --quit&quot;);&lt;br /&gt;#system(&quot;nice -n -5 totem --fullscreen /home/root/playlist.xml &amp;&quot;);&lt;br /&gt;$cmdline_start = &quot;nice -n -5 mplayer /home/root/*.mov &amp;&quot;;&lt;br /&gt;system($cmdline_start);&lt;br /&gt;&lt;br /&gt;open(FILE, &quot;/dev/input/event0&quot;);&lt;br /&gt;binmode(FILE);&lt;br /&gt;while(1)&lt;br /&gt; {&lt;br /&gt;  eval&lt;br /&gt;   {&lt;br /&gt;    local $SIG{ALRM} = sub { die(&quot;Alarm!\n&quot;) };&lt;br /&gt;    alarm(60*28); # 28 minutes&lt;br /&gt;    read(FILE, $buf, 16);&lt;br /&gt;    alarm(0);&lt;br /&gt;   };&lt;br /&gt;  if($@)&lt;br /&gt;   {&lt;br /&gt;    printf(&quot;Restarting due to timeout\n&quot;);&lt;br /&gt;    #system(&quot;totem --next&quot;);&lt;br /&gt;    system(&quot;killall -15 mplayer&quot;);&lt;br /&gt;    sleep(1);&lt;br /&gt;    system(&quot;killall -9 mplayer&quot;);&lt;br /&gt;    sleep(1);&lt;br /&gt;    system($cmdline_start);&lt;br /&gt;   }&lt;br /&gt;  else&lt;br /&gt;   {&lt;br /&gt;    ($time1, $time2, $type, $code, $value) = unpack(&quot;iissi&quot;, $buf);&lt;br /&gt;    printf(&quot;%f %05d %05d 0x%08x\n&quot;, $time1+$time2/1000000, $type, $code, $value);&lt;br /&gt;    if($code == 276 &amp;&amp; $value == 1) # USER button pressed&lt;br /&gt;     {&lt;br /&gt;      printf(&quot;Restarting due to USER button press\n&quot;);&lt;br /&gt;      #system(&quot;totem --next&quot;);&lt;br /&gt;      system(&quot;killall -15 mplayer&quot;);&lt;br /&gt;      sleep(1);&lt;br /&gt;      system(&quot;killall -9 mplayer&quot;);&lt;br /&gt;      sleep(1);&lt;br /&gt;      system($cmdline_start);&lt;br /&gt;     }&lt;br /&gt;   }&lt;br /&gt; }&lt;/pre&gt;&lt;/noscript&gt;\r
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