The problem is that the program (and file handles) work differently than you think :

  1. You open the log file. The OS gives you back a number. Let's call this number the 'file handle'.
  2. The external program gets run, and is handed that number.
  3. A new day breaks.
  4. Your program closes its file handle via the number.
  5. Your program opens a new file and gets a new handle.
  6. The still running application still writes to the old file handle.

Under Linux and possibly also under Windows NT and higher, you can rename the file while it is still open, depending on the open mode / locking mode (there is a savelogs script that does just that). If this does not work with the external program, you will have to stop and restart the application to rotate the logfile.

Update: Fixed link, thanks to Tomte

perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web

[download]

In reply to Re: how to cath STDOUT from an external app, that never exits? by Corion
in thread how to catch STDOUT from an external app, that never exits? by ThorstenHirsch

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