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variables in regular expressions

jknash
stranger

Jul 6, 2001, 10:05 AM

Post #1 of 4 (15682 views)

variables in regular expressions	Can't Post

I am trying to use 2 variables in my regex and I can't get it to work. I can never get it to evaluate to true. Here's a code snippet ------>

#!/usr/bin/perl

%hash = (data => "172.31.1.1");

$entry = "172.31.1.1_se0.1.html";

if ($entry =~ m/%hash->{'data'}+/) {

print "Match\!\n";

}

Can someone please tell me what I'm doing wrong?

thanks for your help

randor
User

Jul 6, 2001, 10:45 AM

Post #2 of 4 (15678 views)

Re: variables in regular expressions [In reply to]	Can't Post

jknash,

replace:

if ($entry =~ m/%hash->{'data'}+/) {

with:

if ($entry =~ m/$hash{'data'}+/) {

I Hope this helps...

perl programmers don't die.. they just start writing a new script.

jknash
stranger

Jul 6, 2001, 12:15 PM

Post #3 of 4 (15676 views)

Re: variables in regular expressions [In reply to]	Can't Post

I tried that and now I get a match every time,,,whethere the hash is included in my script or not. I am running a program called mrtg to monitor our routers which outputs some html files for each router into a predefined directory. I want to do a couple of things with the html files. The html files are named the same - 172.30.12.1.se0.1.html is a good example. I want to parse the ip address out of the filename and compare it to a record in a table in the mysql database. If it's found in the database, I want to query and see if the ip(172.30.12.1) and interface(se0.1) exist in the interfaces table. So basically I need to setup the query, execute it, read the path where the file should be, if it's there parse the filename and put the ip/interface into the interfaces table. That shouldn't be too hard with perl, right? :-)

thanks for all of your help

mhx
Enthusiast

Jul 6, 2001, 12:58 PM

Post #4 of 4 (15675 views)

Re: variables in regular expressions [In reply to]	Can't Post

Hi,

I've commented the code, so it shouldn't be hard to understand.

Code

#!/usr/bin/perl -w 
use strict; 
use warnings; 
  
# Use the following to see what the 
# regex engine is actually doing... 
use re 'debug'; 
  
my $entry = "172.31.1.1_se0.1.html"; 
  
my %hash = (data => "172.31.1.1"); 
  
# All strings that are about to be 
# interpolated into a regex should 
# be quotemeta'd before. Otherwise, 
# the dots will match any character! 
$_ = quotemeta foreach values %hash; 
  
# Now, we want to check if $entry 
# begins with $hash{data}... 
if( $entry =~ /^$hash{data}/ ) { 
  print "Match!\n"; 
}

If you have any specific questions, feel free to ask. Hope this helps.

-- Marcus

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