in reply to Automatically killing a child

Massyn:

I don't know what's going on, so this is pure speculation. But I think that tail is waiting until its input stream is closed. But with your script, tail's input stream is the terminal session's output stream (STDOUT). Thus, I think tail is waiting for your terminal session to close it's output stream before it exits.

Again, this is pure speculation....

--roboticus

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Re^2: Automatically killing a child
by Massyn (Hermit) on May 24, 2006 at 21:45 UTC
    Hi everyone,

    This was a real interesting topic, and ++ to all for your great contributions. In the end, I removed tail from the code, and just hard coded a simple perl based tail into my code. That works, plus I don't have to fork another process. 

    #!/usr/bin/perl

# Known issue
# If the file gets truncated, the script will not terminate
# ====================================================================
+=========
use IO::Handle;
autoflush STDOUT;
use Fcntl qw(:seek);

$file = 'mylog.txt';
$started = 0;    #set to 1 if you want the file to start reading from 
+the start of the logfile

while(1)
{
    open LOG, $file or die "$file could not be opened.";

        seek LOG, $pos, SEEK_SET if defined $pos;
        while(<LOG>)
        {
                chomp;
                if($started)
                {
            print "$_\n";
                }
        }
        $pos = tell LOG;
        close LOG;

        sleep 1;
        $started = 1;
}
exit(0);

    [download]

    Thanks! 

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