Here's a contrived example

#!/usr/bin/perl

# Never leave home without these!
use strict;
use warnings;

# Loop through the faux data log, and...
while (<DATA>) {

    # ...find lines that might be interesting...
    if (/--/) { 

        # ... but ignore certain ones, like those
        # that say "logging" or "disconnected".
        unless ( /logging/ || /disconnected/ ) {

            # Print the rest.
            print "NOTE: $_";

        }

    }

}

# Our faux data for this example
__DATA__
081407 start up server
081407 -- fatal error in procedure 1
081407 -- disconnected user
081407 -- logging started
081407 -- not enough space
[download]

This produces:

NOTE: 081407 -- fatal error in procedure 1
NOTE: 081407 -- not enough space
[download]

Hope this helps,
-v

I like Velaki's approach; take everything and filter out the ones you know you want to ignore. If something new comes in, you can assess that and then update your ignore list if it's not important.

If you did it the other way (listing only what you want), then something new might be ignored that you actually want.

In the next value frame, you might externalize the list of known "ignore" patterns. That way you wouldn't be updating your code, but a config file instead.

---

I humbly seek wisdom.

thank you guys for helping a noob. you have helped a lot! thanks velaki for giving me that code!

If you want to look up the errors in the logfile for context later on, it would be handy to also print out $. which will contain the line number of the logfile you are currently reading.

while ( <DATA> )
{
    next if m/(?:start up server)|(?:-- logging started)|(?:-- disconn
+ected user)/;
    print
}
__DATA__
081407 start up server
081407 -- fatal error in procedure 1
081407 -- disconnected user
081407 -- logging started
081407 -- not enough space
[download]

Output:

081407 -- fatal error in procedure 1
081407 -- not enough space
[download]

You should ask your friend to tell you how to format your posts, and read How do I compose an effective node title? and Writeup Formatting Tips.

sorry for the bad formatting. its my first time to use this. i was thinking more of somethingl ike this:

$regex = qr/--/

if($thestring =~ $regex || $thestring !~ $regex)
{
   unshift(@match, $thestring);
}
[download]

but the problem is the logfile is a bit dynamic and i dont know what errors i am going to get. i just know that "--" usually indicates an error but not all lines with "--" means that they are really errors. so in this sample log file:

081407 start up server
081407 -- fatal error in procedure 1
081407 -- disconnected user
081407 -- logging started
081407 -- not enough space
[download]

i just want to get

081407 -- fatal error in procedure 1
081407 -- not enough space
[download]

and disregard the rest like:

081407 -- disconnected user
081407 -- logging started
[download]

is there a way i can use it in qr// function? i guess something like this:

1. get all occurrences of "--".
2. in those occurrences of "--" ignore those that have "logging" and "
+disconnected"

could it be place in a qr// function like:

qr/-- || ~! logging,disconnected/ (wrong syntax of course)

something like an ignore list.
[download]

hope thats clearer

but the problem is the logfile is a bit dynamic and i dont know what errors i am going to get. i just know that "--" usually indicates an error but not all lines with "--" means that they are really errors. so in this sample log file

Well then, your first step is to find out either what you want, or what you don't want. No regular expression is going to solve that one for you.

Thanks for taking the time to properly format your post. It is most appreciated.

Second suggestion: provide some sample expected output.

It will be much easier for others to help you if you follow these simple suggestions.

The post box doesn't automatically convert \n to <br>

You've gotta put in your own html. <p></p> blocks, and an unordered list <ul></ul> would work well for your post.