Perl - Regex line that starts with "Out[1]="

Question

I have a Perl script to capture Mathematica output, but am trying to find a good way to just catch the line starting with "Out[1]".

I thought I would just check if ( $line =~ /^Out[1]=/ )

What am I doing wrong? Code is below, and then output of program below that:

#!/usr/bin/perl
#perl testMathy.pl
use strict;
use warnings;

### Test 1: Print entire Mathematica output from calling Roots[]
my @charPoly = "-R^3 + R^2 + 3*R - 3";
my @roots = `echo \" Roots[@charPoly == 0, R] \" | math`;

print "\n***ROOTS (TEST 1)***: [@roots]\n~~~~~~~~~~\n";

### Test 2: Print line beginning with Out[1]
my $rootList = "";

for my $line ( @roots ){
        #take line that starts with Out[1]
        print "LINE:", $line;
        if ( $line =~ /^Out[1]=/ ){
            print "success\n";
            $rootList .= $line;
            last; #break
        }
    }

print "\n***ROOTS (TEST 2)***: $rootList\n~~~~~~~~~~\n";

Output:

***ROOTS (TEST 1)***: [Mathematica 10.1.0 for Linux x86 (64-bit)
 Copyright 1988-2015 Wolfram Research, Inc.

 In[1]:= 
 Out[1]= R == Sqrt[3] || R == -Sqrt[3] || R == 1

 In[2]:= 
]
~~~~~~~~~~
LINE:Mathematica 10.1.0 for Linux x86 (64-bit)
LINE:Copyright 1988-2015 Wolfram Research, Inc.
LINE:
LINE:In[1]:= 
LINE:Out[1]= R == Sqrt[3] || R == -Sqrt[3] || R == 1
LINE:
LINE:In[2]:= 

***ROOTS (TEST 2)***: 
~~~~~~~~~~

Why is ROOTS(TEST 2): blank?

Answer 1

Square brackets are special characters in a regex. Try: $line =~ /^Out\[1\]=/

I'd recommend reading a regex tutorial like this one to learn this kind of thing.