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

# words to search for
my @words = qw( wort1 wort2 wort3 wort4 );

# built a regex for the search; each word is to be treated as string
my $regex = join '|', map {"\Q${_}\E"} @words;          # list of alternative strings
$regex    = qr{($regex)};                               # capture the match

my %position;
while ( my $line = <DATA> ) {

        # save line number ($.) of each occurence in read lines;
        # use a while loop to catch multiple words in line
        push @{ $position{$1} }, $.     while $line =~ m{$regex}g; 
}

# show result
for my $word ( sort keys %position ) {
        printf "%s Zeile: %s\n", $word,join ", ", @{$position{$word}};
}



__DATA__
aaaa, aaaaa, aaaaaa, aaaaaa, wort1, aaaa, aaaa,
bbbbb, bbbbb, bbbb, wort2, bbbbb, bbbb, bbbbbb,
cccccc, ccccc, cccc, cccccc, wort3, cccc, cccc,
ddddd, dddddd, wort1, dddddd, ddddd, dddd, ddd,
eee, eee, eeeeee, eeeeeeee, wort4, wort2, eeee,

wort1 Zeile: 1, 4
wort2 Zeile: 2, 5
wort3 Zeile: 3
wort4 Zeile: 5