我目前正在使用 cron 作业来拥有一个 perl 脚本，该脚本告诉我的 arduino 循环我的鱼菜共生系统，一切都很好，除了 perl 脚本没有die按预期进行。
这是我的 cron 工作：
*/15 * * * * /home/dburke/scripts/hal/bin/main.pl cycle
下面是我的 perl 脚本：
#!/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->databits(8);
$port->baudrate(19200);
$port->parity("none");
$port->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, '>>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->write('2'); # Signal to set pin 3 low
print "Sent cmd: 2\n";
$stop = 1;
};
$signalOut = $port->write('1'); # Signal to arduino to set pin 3 High
print "Sent cmd: 1\n";
print "Waiting for plant bed to fill...\n";
print LOG "Alarm is being set.\n";
alarm (420);
print LOG "Alarm is set.\n";
while ($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 = $port->lookfor(9);
# If we get data, then print it
if ($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($choice = <STDIN>);
switch ($choice) {
case /1/ {
$SIG{ALRM} = sub {
print "Expecting plant bed to be full; please check.\n";
$signalOut = $port->write('2'); # Signal to set pin 3 low
print "Sent cmd: 2\n";
};
$signalOut = $port->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->write('2'); # Signal to set pin 3 low
print "Sent cmd: 2";
$lastChoice = $choice;
}
case /3/ {
$signalOut = $port->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";}
}
}
}
}
当我运行时，ps -ef我发现以下输出：
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
不应该只有一个过程吗？即使它收到了循环参数并且分叉在循环参数的if块之外，它是否也在分叉？
知道为什么它不会因声明而死die "Done.";吗？它可以从命令行正常运行，并可以很好地解释“循环”参数。当它在 cron 中运行时，它运行良好，但是，进程永远不会死掉，虽然每个进程都不会继续循环系统，但它似乎确实在以某种方式循环，因为它会非常快地增加我的系统负载。
如果您想了解更多信息，请询问。多谢你们！