Don't use shell meta-characters (such as >) and the shell won't get involved. Or use IPC::Open3's open3 instead of open '...|'.

One important difference between open and open3 is that open will call waitpid for you when the file handle is closed (implicitely or explicitely), while open3 won't. You have to call waitpid if you use open3 or you'll end up with zombies.

I wasn't too bothered by the redirection, it was just to remove any error messages from tail.
When it was removed all was well!

Thanks for all this help, I've learned quite a bit. I never knew about the END block or that the redirection would get the shell involved. Thanks again.

I don't use *nix, so this is something I've read about rather than done for myself, but...

there is mention (in perlfunc open, maybe more in perlopentut?) of a more-than-3-argument form of the piped open. open FILEHANDLE,MODE,EXPR,LIST

The idea is that you bypass the shell and run the command (tail in this case) directly, and so get the handle of the tail process returned rather than that of the shell. It would look something like:

my $tail_id = open my $tail_fh, '-|', 'tail', '-1lf', 'info_file' or d
+ie ...;
END{ 
    kill 3, $tail_id;
}
[download]

The caveat is that the shell is what performs the redirection of stderr in your example, so you cannot do that with this form of open.

If that is a requirement then you are into using IPC::Open3 with all the complexities that entails.