AWESOME! That's *EXACTLY* what I needed! I didn't realize I could use logrotate for
tasks other than, well, just
rotating logs. Thanks!!
----- Original Message -----
From: "John McKown" <[EMAIL PROTECTED]>
To: "Perl Beginners Mailing List" <[EMAIL PROTECTED]>
Sent: Thursday, January 29, 2004 5:43 PM
Subject: Re: logrotate and perl file handles. How do I know when to reopen my log file?
: What is happening is that once a file has been opened, the handle points
: to the "inode" which is an internal "number". This "number" is unique for
: a filesystem and identifies the file regardless of its "name" in the
: directory. That is why your Perl program is "following" the "old name".
: Anyway,
:
: What you need to do is create an entry in /etc/logrotate.d. Look at one of
: the entries in there for an example of how to code it. Oh, I think you've
: already done this.
:
: What your Perl program needs to do is:
:
: 1) write its PID to a known location. Many put this is /var/run. Something
: like:
:
: open (PIDFILE,">/var/run/myPerlScript.pid") or die "cannot open pid file
: $!";
: print PIDFILE "$$";
: close(PIDFILE);
: ...
:
: 2) Determine the "signal" that you want logrotate to issue to tell your
: script to reopen its log file. Many programs use the HUP signal. Create a
: signal handler in your Perl program to field this signal to close and
: reopen its log file. This is the main "magic" to get this working. I'd
: make LOGHANDLE an "our" variable at the top of the Perl program. Replace
: LOGHANDLE with the correct variable, of course <grin>.
:
: $SIG{HUP} = sub {
: close(LOGHANDLE);
: open(LOGHANDLE,">/var/log/myPerlScript.log") or die "cannot open
: logfile $!";
: };
:
: 3) Create the aforementioned logrotate entry in /etc/logrotate.d something
: like:
:
: /var/log/myPerlScript.log {
: notifempty
: missingok
: postrotate
: /usr/bin/kill -HUP `cat /var/run/myPerlScript.pid
: >/dev/null` 2>/dev/null || true
: endscript
: }
:
: perhaps calling it "myPerlScript.log". Note - replace "myPerlScript" with
: the actual name of your Perl script. Note that when the signal handler
: actually executes, the previous myPerlScript.log file has already been
: renamed, so the open in the signal handler create a new file with the old
: name.
:
:
: On Thu, 29 Jan 2004, TeamSolCO wrote:
:
: > I have written a long running perl application to help me with some
: > trivial administrative functions. Due to the
: > volume of logging generated by this application, I am managing its
: > output with logrotate. The problem I face is that
: > perl is "following" the log files that logrotate swaps out. While this
: > is probably intelligent on perl's part (to
: > follow the file descriptor rather than the file name), it is presenting
: > a major problem for me. When "logfile" becomes
: > "logfile.1" (etc), my application follows that move and "continues"
: > logging to the new "logfile.1" instead of losing
: > that file handle -- a condition which I check for so that I can reopen
: > the log file using the proper file name,
: > "logfile".
: > Ultimately, perl will only lose the file handle when logrotate
: > finally deletes the "last file" in the log rotation
: > scheme. Unfortunately, I will have lost a week's worth of logs
: > because all that data will have been in the single file.
: > Additionally, I'll have several empty log file copies named .1, .2, .3,
: > etc. How can I set perl to NOT follow the file
: > when it is renamed by logrotate, such that a condition will be created
: > where I will be able to initialize the
: > replacement file?
: >
: > Thanks!!
: >
: > - William Kimball
: > "Programming is an art-form that fights back!"
: >
:
: --
: Maranatha!
: John McKown
:
:
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