Four problems. (Aside from not previewing your node. Use <c>...</c> around code in your nodes.)

• You call your file handle TABLE, table and IN. The name is case-sensitive, and using the wrong name obviously won't work. Furthermore, you're better off using lexical file handles:

  open(my $fh, '<', $inputs)
     or die ...
  
  while (<$fh>) { ... }
  
  close($fh);  # Optional.
  [download]

• Similarly, you read each line into $line, yet you use $_ further on.

• Third, keep in mind that the lines returned by the <HANDLE> operator include a trailing newline. Use chomp($line); as the first line of the while loop if you wish to remove this newline.

• Finally, you treat $string as if it's a regexp while it's probably just text. (Added for clarification: If $string contains text as opposed to a regexp, you can convert the text to a regexp using \Q...\E or quotemeta. )

  if ($line =~ /\Q$string\E/) { ... }
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  If you want to check for equality:

  if ($line eq $string) { ... }
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if ($line =~ /\Q$string\E/) { ... }

This is a good idea. I didn't make the leap to quoting the string when building the regex, but that's probably what the OP wants.

Is this what the actual code looks like?

#!/usr/bin/perl
$string = 'test';
$inputs = 'test.txt';

open(TABLE, $inputs) or die "can't open $inputs.\n";

while ( $line = <IN> ) {
    if ( $_ =~ $string ) { print $_; }
}
close(IN);
[download]

If that's the case, then I see at least these problems at a glance:

• you're not reading the file you are opening. You're certainly not closing the one you're opening. open and close will tell you about what those items you're passing to open() and close() do.
• You're also assigning the readline (<filename>) operator's results to $line, then working on $_ which is the default variable which would have otherwise taken that value. perlvar can help you figure that out.
• You then test a scalar variable against a scalar variable without anything other than the binding operator. You need a regular expression match. perlre and Regexp Quote Like Operators operator, regexp should help with that.

You might try the below code (untested):

#!/usr/bin/perl
use strict;
use warnings;

my $string = 'test';
my $inputs = 'test.txt';

# see perlfunc
open( my $in, '<', $inputs) or die "can't open $inputs.\n";

while ( <$in> ) { # see perlsyn, perlop
    if ( $_ =~ m/^$string(.*)/ ) { # see perlre
        print $1; # see perlvar, perlre
    }
}
close( $in ); # see perlfunc
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#!/usr/bin/perl
use strict;
use warnings;

while ( <> ) {
# takes filenames on the command line or STDIN if none
    print ( ( split )[1] );
}
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BTW, Perl is a wonderful tool, but you might also want to 'man 1 cut' if you're using a Unixy OS.

Update: The code was missing a couple of $ sigils. Thanks to ikegami for pointing it out to me.

#!/usr/bin/perl 
use warnings;
use strict;
#
# Using __DATA__ to test a loop.
#
my $string = 'test'; 
my $inputs = 'test.txt'; 
# open(my $table, "<", $inputs) or die "can't open $inputs.\n"; 
# while (<$table>) { 
while (<DATA>) { 
    print if ( m/\Q$string\E/o );
} 
# close($table); 
__DATA__
test
tst
foo bar test
This is a test
This is something else.
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C:\Code>perl match.pl
test
foo bar test
This is a test
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use strict;
use warnings;
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near the start of the programs they posted. Those two statements are the most important Perl you'll ever learn. Put them in every program you write. They will save you many, many hours of heartache.

Use code tags. Refer to Writeup Formatting Tips.

Show your exact input data.

Show your desired output data.

What might I be missing below, because it doesn't seem to work on UNIX
+?
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...
PrivoxyWindowOpen(TABLE, $inputs) or die "can't open $inputs.\n";
...
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