I wish I could use Proc::Daemon, but I need to resort the creating my own daemon code. This daemon calls a script that performs a few input and output operations periodically. One of the input and outputs commands in the script is 'sed', using 'echo' to append to a file, using 'printf' to log to a logfile.

The 'sed' commands are not working from the script. One of the errors messages is bad file descriptors. The 'echo' commands are echoing too may lines.

Is best to not call a script and just rewrite the shell script using Perl?

Or am I fundamentally missing something in my Perl code in calling the shell script? 

#!/usr/bin/perl -Tw
#
#

use strict;
use POSIX qw(setsid);

use constant VERSION => 1.10;

$ENV{'PATH'} = '/bin';
delete @ENV{qw(IFS CDPATH ENV BASH_ENV)};

my $PID_FILENAME = "/var/run/one-user-only.pid";
my $ONE_USER_ONLY = "/usr/local/bin/one-user-only.sh";

#
# If this file does exist, then just die accordingly
#
die("$PID_FILENAME exists!!") if ( -f $PID_FILENAME );

#
# If this file does not exist, then just die accordingly
#
die("Cannot find $ONE_USER_ONLY") if ( ! -f $ONE_USER_ONLY );

sub daemonize {

    chdir "/";

    # Close all default file descriptors
    open (STDIN, "</dev/null");
    open (STDOUT, ">/dev/null");
    open (STDERR, ">&STDOUT");
    
    my $pid = fork ();

    # Write the PID to /var/run
    open (FD, ">$PID_FILENAME") or die("Cannot write PID: $!");
    print FD "$$\n";
    close(FD);

    # Detach from the terminal so interrupts cannot occur
    if ($pid < 0) {
        die "fork: $!";
    } elsif ($pid) {
        exit 0;
    }

    # Make session leader
    setsid or die "setsid: $!";
    umask 0;

    foreach (0 .. (POSIX::sysconf (&POSIX::_SC_OPEN_MAX) || 1024)) {
        POSIX::close $_
    }
}

my $continue = 1;
$SIG{TERM} = sub { unlink $PID_FILENAME; $continue = 0; };

&daemonize;

while ($continue) {
    sleep 2;
    system($ONE_USER_ONLY);
}

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In reply to Perl Daemon Calling a script by perlology

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