Re: Multiline Regex replacement in Multiline file

[Athanasius]

Hello akamboj84, and welcome to the Monastery!

You first create a dictionary mapping each search regex to its corresponding replacement text. Then, before searching, you change the search regex in two ways: (1) by concatenating all the search strings with |; (2) by applying the qr operator. So when you get to the substitution, if a match is found the dictionary lookup $dic{$matchkey} is guaranteed to fail, since the new value of $matchkey does not match any of the keys in the %dic hash!

But even when this problem has been fixed,¹ you will still be replacing the whole of the first user entry, including everything through to the final "engineer", with the single text REPLACE1. I doubt this is what you want. For the monks to help you further, you will need to specify the output you expect/desire.

Update: ¹For example:

use strict;
use warnings;

my @regexen =
(
    q{\s+user\s"[^"]+"\s+password\s"[^"]+"\s+hash2\s+access(\s+console
+){2}} .
    q{(\s+new-password-at-login)?} .
    q{(\s+member\s"(default|engineer|networktest)"){2}(\s+exit){0,2}},

    q{\s+user\s"[^"]+"\s+password\s"[^"]+"\s+hash2\s+access(\s+console
+){2}} .
    q{(\s+new-password-at-login)?} .
    q{(\s+member\s"(default|READ-ONLY)"){2}(\s+exit){0,2}},

    q{\s+user\s"[^"]+"\s+password\s"[^"]+"\s+hash2\s+access} .
    q{(\s+(console|snmp|li)){3}\s+console(\s+new-password-at-login)?} 
+.
    q{(\s+member\s"(default|LI|li-prof1)"){2}(\s+exit){0,2}},
);

my $n    = 1;
my %dic  = map { qr{$_} => 'REPLACE' . $n++ } @regexen;
my $line = join "", <DATA>;

for my $matchkey (keys %dic)
{
   $line =~ s%$matchkey%$dic{$matchkey}%g;
}

print $line;

__DATA__
 user "testuser1"
                password "08Cl3V.leJKU/GskqArA0Yp4MFo" hash2
                access console
                console
                    new-password-at-login
                    member "default"
                    member "engineer"

 user "v-test"
                password "VCp0GjSBK/KiWW.PgkQp7swXVMZ" hash2
                access console
                console
                    new-password-at-login
                    member "default"
                    member "READ-ONLY"

Output:

18:42 >perl 1011_SoPW.pl
REPLACE1REPLACE2

18:43 >

Note that I had to add two doublequote characters to the second regex to get it to match.

Hope that helps,

[akamboj84]

Hi Athanasius, Thanks for that stuff. But I already have a working code like this. But I wanted to avoid the below "for" loop and instead do multi regex replacement.

for my $matchkey (keys %dic)
{
   $line =~ s%$matchkey%$dic{$matchkey}%g;
}

Also for each regex I have seperate set of pre defined replacement String not like Replace1 or Replace2( that was just used as an example) and I want replace the complete matched string with predefined Replacement String.

[Athanasius]

Hello again, akamboj84,

But I wanted to avoid the below "for" loop and instead do multi regex replacement.

...as my regex file is a long one and also i need to process a lot of files, so its kind of time/cpu consuming. I want to get rid of "for" loop...
— Re^3: Multiline Regex replacement in Multiline file

There may be some clever way to do this using Perl’s extended regular expression patterns, but if so I haven’t found it. But deployment of the for loop can likely be made much more efficient. At present, the regexen are being applied to the whole input file; but if you can read in a paragraph at a time, this will save a lot of processing, as there will then be no need for the regex engine to re-search those parts of the input string that have already been matched and replaced:

Read more... (2 kB)

Hope that helps,

[akamboj84]

Hi Athanasius, the only solution i was looking for was to avoid loops, otherwise i am already doing it via looping through Keys and replacing matching string. I am not an expert but this is what i have been doing already :)

 
my $line=join "", <F>;
foreach $k (keys %dic) { 
 $line =~ s/$k/$dic{$k}/gism;
}
print $line;