Problems with grep

spstansbury has asked for the wisdom of the Perl Monks concerning the following question:

I'm having problems getting the output I need.

"founds_vuln_test" is just a list of IP addrs and an associated CVE vulnerability ID.
"CVE_data_Demo" is a csv file of CVE ID and a list of their attributes.

#!/usr/bin/perl

use strict;
use warnings;

open (DATA, "found_vulns_test");
open (CVE_ID, "CVE_data_Demo");

my @cve_list = <CVE_ID>;
    

while (<DATA>) {
    chomp;
    my @list = split/,/;
    my $vuln = $list[1];
    
    my @matched = (grep (/$vuln/, @cve_list));
    
# works up to here - grep outputs a string, right? But when I get to t
+he next line, I get the scalar/count output...
    
    my @matched_cve = split(',', @matched);
    
    
    
# Then I want to go through the fields as in the snippet below:
    

    $_= $matched_cve[1];
    if( /COMPLETE|[C]/i ) {
        $biasedConf= 100;        # percentage Confidentiality Impact v
+alues
    } elsif( /PARTIAL|[P]/i ) {
        $biasedConf= 50;        # percentage Confidentiality Impact va
+lues
    } elsif( /NONE|[I]/i ) {
        $biasedConf= 0;            # percentage Confidentiality Impact
+ values
    } else {
        $biasedConf= 0;            # percentage Confidentiality Impact
+ values
    };


}
[download]

Any help would be greatly appreciated!

Best regards,

Scott...

Comment on Problems with grep Download Code

Replies are listed 'Best First'.
Re: Problems with grep by citromatik (Curate) on Jan 30, 2009 at 14:11 UTC
grep outputs a string, right? But when I get to the next line, I get the scalar/count output... `my @matched_cve = split(',', @matched);` [download] grep returns a list not a scalar. Also, split evaluates the expression in scalar context that is why you are getting the count of the elements in `@matched` citromatik	[reply] [d/l] [select]
Re: Problems with grep by johngg (Canon) on Jan 30, 2009 at 15:14 UTC
I wonder if you would be better off parsing the "CVE_data_Demo" file into a hash rather than slurping the file into an array and repeatedly greping over it. Then you would be able to do a simple hash lookup for each line of your "found_vulns_test" file. It would be useful to see a sample of the data, sanitised if necessary, to form a better judgement. It appears that you are matching against an alternation of, for example, '`PARTIAL`' or '`[P]`' but you should note that square brackets are regular expression metacharacters that enclose a character class; in this case a class with a single member, 'P'. They should be escaped to match literals. `... } elsif( /PARTIAL\|\[P\]/i ) { ...` [download] Again, I wonder if a hash might be better. `... my %biasedConfLookup = ( COMPLETE => 100, q{[C]} => 100, PARTIAL => 50, q{[P]} => 50, NONE => 0, q{[I]} => 0, ); ... $biasedConf = exists $biasedConfLookup{ uc $_ } ? $biasedConfLookup{ uc $_ } : 0; ...` [download] Another point; you should always check for the success or otherwise of your open statements and it is recommended that you use the three-argument form with lexical filehandles `open my $foundVulnsFH, q{<}, q{found_vulns_test} or die qq{open: < found_vulns_test: $!\n};` [download] and you should avoid using the `DATA` filehandle for a file you open, as filehandle of that name is opened automatically for you by the perl interpreter if your script contains data inline after `__DATA__` or `__END__` tags. I hope these points are helpful. Cheers, JohnGG	[reply] [d/l] [select]
Re: Problems with grep by Anonymous Monk on Jan 30, 2009 at 14:16 UTC
# works up to here - grep outputs a string, right? But when I get to t +he next line, I get the scalar/count output... Grep returns scalars, example `D:\>perl -e"die grep /6/, 3 .. 6,6,6" 666 at -e line 1.` [download] your problem is you're misusing split, example `D:\>perl -e"die split 1, 121314" 234 at -e line 1. D:\>perl -e"die split 1, 121314, 1" 121314 at -e line 1. D:\>perl -e"die split 1, 121314, 2" 21314 at -e line 1. D:\>perl -e"die split 1, 121314, 3" 2314 at -e line 1. D:\>perl -e"die split 1, 121314, 4"` [download] you may have intended `my @matched_cve = map { split(',', $_) } @matched;` [download]	[reply] [d/l] [select]
Re^2: Problems with grep by citromatik (Curate) on Jan 30, 2009 at 14:36 UTC
Grep returns scalars, example `D:\>perl -e"die grep /6/, 3 .. 6,6,6" 666 at -e line 1.` [download] grep returns a list, and in scalar context, the number of elements the expression was true. In your example, die outputs the list returned by grep: `perl -e "die scalar grep /6/, 3 .. 6,6,6" 3 at -e line 1.` [download] What you did is essentially the same as: `perl -e 'die qw/1 2 3/' 123 at -e line 1.` [download] citromatik	[reply] [d/l] [select]
Re^3: Problems with grep by Anonymous Monk on Jan 30, 2009 at 14:58 UTC
`\| \\|/ scalars<-- /\|\ \|` [download] `perldoc -f grep` is better :)	[reply] [d/l] [select]
Re^4: Problems with grep by citromatik (Curate) on Jan 30, 2009 at 15:11 UTC
Re^5: Problems with grep by ikegami (Patriarch) on Jan 30, 2009 at 15:31 UTC
Re^2: Problems with grep by spstansbury (Monk) on Jan 30, 2009 at 14:59 UTC
I knew that I was misusing something! Thanks for your help... As a brand new member, I can only say that I am astounded by the support here. The timeliness and helpfulness of the responses is incredible! Thank you all again! Scott...	[reply]
Re^3: Problems with grep by locked_user sundialsvc4 (Abbot) on Jan 30, 2009 at 16:44 UTC
Welcome. “Come, friend, and do likewise.”