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# 1  
Old 10-28-2002

can i include this command into my crontab file

> /var/adm/wtmp

to clear the contents on a regular basis ?
what about file permissions ?
# 2  
Old 10-28-2002
Just as a suggestion.

You could do the following..

## - Suitable comment here.
[mm] [hh] * * * rm /var/adm/wtmp ; touch /var/adm/wtmp ; chmod ??? /var/adm/wtmp

Makes it easier to read and even more so for newbie's who happen to be learning what is being run from cron.
# 3  
Old 10-28-2002
I would really recommend using ">" to truncate the file, rather than rm it, and have a different file (different inode) used for the next.

Depending on your Unix version, you may be able to use something like "logrotate". You'll probably need to install a version for your Unix, if one exists.
# 4  
Old 10-29-2002
I will admit, my suggestion is a long-winded approach.

I didn't know of the inode detail that LivinFree raised, thanks LivinFree.
# 5  
Old 10-29-2002
Aix 3.2

ancient i know but just one module still runs on this server , we have migrated to solaris 8 . I've never heard about logrotate livinfree... whats it abt

# 6  
Old 10-29-2002
Logrotate is typically distributed with Linux systems, but should be fairly simple to port over to others, since it's based (I believe) on perl. It's run via cron, and each time it runs, checks a set of config files that define archival, truncation, etc of log files.

If you just want to clear out that one periodically, it may just be easier to whip up a little script that cp's it to another file (in case you want to review it later), compresses the archive, and truncates that file.
# 7  
Old 10-29-2002
Originally posted by LivinFree
If you just want to clear out that one periodically, it may just be easier to whip up a little script that cp's it to another file (in case you want to review it later), compresses the archive, and truncates that file.
Here is a little Perl script that I cooked up for automagically rotating logs of an application that sends the data to STDOUT and redirected to file.

Seems that in the above situation that you can't just cp the file as the inode pointer will still point at the new filename and keep on adding data (I simulated this on my FreeBSD system for a thread on another forum).


# Real cheezy attempt at piping STDOUT into a perl routine to automagically
# rotate logs. Idea inspired by cRock.
# Auswipe sez "Hey, no guarantees!"

my $lineCounter = 0;
my $logCount    = 1;

#open(LOGFILE, ">app.log.$logCount");

while (true) {
  if (($lineCounter > 1000) || ($lineCounter == 0)) {
    open(LOGFILE, ">app.log.$logCount");
    $lineCounter = 1;
    # print STDERR "Rolled log to app.log.$logCount\n";
  $logEntry = <STDIN>;
  print LOGFILE "$logEntry";
  #print STDERR "Made log entry.\n";


./someapp | ./perl_buffer

Hmmm. After looking at my code I realize that I could just keep on incrementing $lineCounter and just use modular arithmatic to set the point to rotate the log. That'll teach me.
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