Re: No tools? Use Perl?!

[codiac]

Your while loop looks at one line at a time but your text says "synopsis (multi line)" ... D'oh!

Even if you are disconnected from the net you must have some modules installed, maybe you can have a look around and see if someone else got a useful module installed.

If not, let's hope the files are small enough to fit in memory

# Suck in the whole file
my $text = do { local $/; <$fh> };

# use a nested group to exclude the close tag
while ($text=~ m{<ReportHost[^>]*>(?:(?!</ReportHost>).)*</ReportHost>
+}s) {
    # print out the content of each ReportHost tag
    print "$1\n";
}

Untested! :)

[haukex]

Hi codiac,

The regexp needs the /g switch or the code will loop forever, and you use $1 but don't have capturing groups.

Regards,
-- Hauke D

[Boyd.Ako]

The regexp needs the /g switch or the code will loop forever, and you use $1 but don't have capturing groups.
I don't know the specifics as to how /g works. All I know is that in other scripts I've wrote it stops at the first instance. Considering that I have multiple <RemoteHost> sections I don't think it will work and thus am assuming that is what I want. I haven't set up $1 captures yet because it should only have one thing being feed to it; the file. I'll work on error handling for invalid input later.

[haukex]

Hi Boyd.Ako,

I don't know the specifics as to how /g works.

/g on an m// match is documented in perlop, in this case: "In scalar context, each execution of m//g finds the next match, returning true if it matches, and false if there is no further match." Since the regexp is being used in a while loop, without the /g modifier it would simply match the first occurrence every time and the loop would never end. With /g, the match advances through the string.

Alternatively: "The /g modifier specifies global pattern matching--that is, matching as many times as possible within the string. ... In list context, it returns a list of the substrings matched by any capturing parentheses in the regular expression." Without /g, it would only find the first match.

When you add the /g and the capturing group to codiac's code it works:

use warnings;
use strict;

my $text = <<'END';
<y><ReportHost>one</ReportHost>
<x>test</x></y>
<ReportHost>
two
</ReportHost>
    <ReportHost><z>thr</z>ee</ReportHost>
END

# m//g in scalar context
while ($text=~ m{<ReportHost[^>]*>((?:(?!</ReportHost>).)*)</ReportHos
+t>}sg) {
    print "a: \"$1\"\n";
}

# m//g in list context
my @m = $text=~ m{<ReportHost[^>]*>((?:(?!</ReportHost>).)*)</ReportHo
+st>}sg;
print "b: \"$_\"\n" for @m;

__END__
a: "one"
a: "
two
"
a: "<z>thr</z>ee"
b: "one"
b: "
two
"
b: "<z>thr</z>ee"

Hope this helps,
-- Hauke D

[Anonymous Monk]

Your while loop looks at one line at a time but your text says "synopsis (multi line)" ... D'oh!

So what is the problem? The tags he is matching do not contain a newline. The flip-flop maintains a state to govern the filter logic; there is no compelling reason to slurp the file.

[Boyd.Ako]

Your while loop looks at one line at a time but your text says "synopsis (multi line)" ... D'oh! What I mean is that the XML object data spans serveral lines between the opening and closing tags. It's not a <tag text="blah blah blah"></tag> but more of a


<tag name="stuff">
blah
blah
blah
</tag>

Even if you are disconnected from the net you must have some modules installed, maybe you can have a look around and see if someone else got a useful module installed.
From instmodsh:

CPAN::Meta
CPAN::Meta::Requirements
CPAN::Meta::YAML
Crypt::Blowfish_PP
ExtUtils::CBuilder
File::SearchPath
IPC::Cmd
JMX::JMX4Perl
JSON::PP
Locale::Maketext::Simple
Module::Build
Module::CoreList
Module::Load
Module::Load::Conditional
Module::Metadata
Params::Check
Parse::CPAN::Meta
Perl
Perl::OSType
Term::Clui
Term::ShellUI
Term::Size
Test::Simple
check_postgres
parent
version

If not, let's hope the files are small enough to fit in memory
I'm iffy to the concept of slurping and generally avoid it due to all the warnings that come with it. The files get anywhere from 3-5MB on a 2GB system with nagios running. Don't know if that's "small" enough.