I have cut down my perlmon to the basics, and here are some ideas you can grab:

1. Use a $RUNFILE that holds in its modification time when it was run last. This way you can compare the modification time of the $IN_FILE, and hopefully skip early because there has been no update.

2. Use an $ERRORSTATE file. Here I have made a modification in that the filesize is the same as the hour you have analized. If not, it is the first encountered error in the current $IN_FILE, and thus, we email.

3. There IS this problem, where you miss out on the logging.

09:59:01 your monitor runs
09:59:50 some error is written to ./logs/09
10:00:01 your monitor runs again, but check ./logs/10 (which probably is empty).

If you really just have 24 directories (one for each hour), then you should keep state files for each one of them (and check modification times), maybe tie them to a file (provides persistant data, like a DB, just good enough)

Assuming you only have one file in the logs directory, you can get all the files like so: 

@CHECK_THESE_FILES = </raid/logs/*>;

[download]

Here is the minimized code:

#!/usr/bin/perl
use strict;
use warnings;


my $HOUR = (localtime(time))[2];
# $HOUR = '0'.$HOUR if $HOUR<10; # make it a 09 instead of 9

my $RUNFILE = "/tmp/minimon.run";
my $ERRORSTATE = "/tmp/minimon.error";

 
my $lastrun = -f $RUNFILE ? (int( (-M $RUNFILE) *60*60*24) || 1) : 0; 
+# Seconds ago it has run. (or 1 if less than 1) 

# touch early to avoid bordercases (we rather check double than not)
if(open(FF, ">", $RUNFILE)){
    close FF;
}else{
    warn "Could not open $RUNFILE, $!";
}

my $IN_FILE = "/tmp/raid/logs/$HOUR";

if (-f $IN_FILE){
    my $fileage = -M $IN_FILE;
    if($lastrun > $fileage){
        print "File $IN_FILE has not been updated, no action";
        exitOK();
    }else{
        # loop through file here and determine exitERROR() or exitOK()
    }
}else{
    warn "No RAID files? I expected $IN_FILE";
}

my $cmd = "cat /raid/logs/`date +%H`";
my $out_file = "/home/resource/certchange.txt";

sub exitOK{
    unlink $ERRORSTATE if -f $ERRORSTATE;
    exit 0;
}

sub exitERROR{
    if(-f $ERRORSTATE && ( -s $ERRORSTATE eq $HOUR) ){
        warn "Already reported an error in $IN_FILE";
        return 0;
    }
    if(open(ERR, ">", $ERRORSTATE)){
        print ERR "." x $HOUR;
        close ERR;
    }else{
        warn "Could not open ERRORSTATE $ERRORSTATE $!";
    }
    # do email thing here 
    exit 0;
}

[download]

In reply to Re^3: How can one open a filehandle in realtime or current log by FreeBeerReekingMonk
in thread How can one open a filehandle in realtime or current log by new2perl2016

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