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POPerl cron job stays running
 

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    <p>I'm currently using a cron job to have a perl script that tells my arduino to cycle my aquaponics system and all is well, except the perl script doesn't <code>die</code> as intended.</p> <p>Here is my cron job:</p> <pre><code>*/15 * * * * /home/dburke/scripts/hal/bin/main.pl cycle </code></pre> <p>And below is my perl script:</p> <pre><code>#!/usr/bin/perl -w # Sample Perl script to transmit number # to Arduino then listen for the Arduino # to echo it back use strict; use Device::SerialPort; use Switch; use Time::HiRes qw ( alarm ); $|++; # Set up the serial port # 19200, 81N on the USB ftdi driver my $device = '/dev/arduino0'; # Tomoc has to use a different tty for testing #$device = '/dev/ttyS0'; my $port = new Device::SerialPort ($device) or die('Unable to open connection to device');; $port-&gt;databits(8); $port-&gt;baudrate(19200); $port-&gt;parity("none"); $port-&gt;stopbits(1); my $lastChoice = ' '; my $signalOut; my $args = shift(@ARGV); # Parent must wait for child to exit before exiting itself on CTRL+C if ($args eq "cycle") { open (LOG, '&gt;&gt;log.txt'); print LOG "Cycle started.\n"; my $stop = 0; sleep(2); $SIG{ALRM} = sub { print "Expecting plant bed to be full; please check.\n"; $signalOut = $port-&gt;write('2'); # Signal to set pin 3 low print "Sent cmd: 2\n"; $stop = 1; }; $signalOut = $port-&gt;write('1'); # Signal to arduino to set pin 3 High print "Sent cmd: 1\n"; print "Waiting for plant bed to fill...\n"; print LOG "Alarm is being set.\n"; alarm (420); print LOG "Alarm is set.\n"; while ($stop == 0) { print LOG "In while-sleep loop.\n"; sleep(2); } print LOG "The loop has been escaped.\n"; die "Done."; print LOG "No one should ever see this."; } else { my $pid = fork(); $SIG{'INT'} = sub { waitpid($pid,0) if $pid != 0; exit(0); }; # What child process should do if($pid == 0) { # Poll to see if any data is coming in print "\nListening...\n\n"; while (1) { my $incmsg = $port-&gt;lookfor(9); # If we get data, then print it if ($incmsg) { print "\nFrom arduino: " . $incmsg . "\n\n"; } } } # What parent process should do else { sleep(1); my $choice = ' '; print "Please pick an option you'd like to use:\n"; while(1) { print " [1] Cycle [2] Relay OFF [3] Relay ON [4] Config [$lastChoice]: "; chomp($choice = &lt;STDIN&gt;); switch ($choice) { case /1/ { $SIG{ALRM} = sub { print "Expecting plant bed to be full; please check.\n"; $signalOut = $port-&gt;write('2'); # Signal to set pin 3 low print "Sent cmd: 2\n"; }; $signalOut = $port-&gt;write('1'); # Signal to arduino to set pin 3 High print "Sent cmd: 1\n"; print "Waiting for plant bed to fill...\n"; alarm (420); $lastChoice = $choice; } case /2/ { $signalOut = $port-&gt;write('2'); # Signal to set pin 3 low print "Sent cmd: 2"; $lastChoice = $choice; } case /3/ { $signalOut = $port-&gt;write('1'); # Signal to arduino to set pin 3 High print "Sent cmd: 1"; $lastChoice = $choice; } case /4/ { print "There is no configuration available yet. Please stab the developer."; } else { print "Please select a valid option.\n\n";} } } } } </code></pre> <p>When I run <code>ps -ef</code> I find the following output:</p> <pre><code>dburke 15294 15293 0 14:30 ? 00:00:00 /bin/sh -c /home/dburke/scripts/hal/bin/main.pl cycle dburke 15295 15294 0 14:30 ? 00:00:00 /usr/bin/perl -w /home/dburke/scripts/hal/bin/main.pl cycle </code></pre> <p>Shouldn't there only be one process? Is it forking even though it received the cycle argument and the fork is outside of the cycle argument's <code>if</code> block?</p> <p>Any idea why it wouldn't die from the statement <code>die "Done.";</code>? It runs fine from the command line and interprets the 'cycle' argument fine. When it runs in cron it runs fine, however, the process never dies and while each process doesn't continue to cycle the system it does seem to be looping in some way due to the fact that it ups my system load very quickly. </p> <p>If you'd like more information, just ask. Thanks guys!</p>
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    1. CODoes it do this when you run the command from the command line or is it specifically a cron problem?
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    2. COIs it blocked somewhere, or is it endlessly looping?
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    3. COI updated my question; sorry for the ambiguity guys. :)
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      1. USDylan
 

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