Unless the exclusionary items you're looking for in column 8 also appear in another column, it's not necessary to isolate column 8 to check for them. If you find them within an entry--as a whole--you can skip that entry:

use strict; use warnings;

my $regex = join '|', map qq|\Q$_\E|, qw(sno=; tail->tail head->head);

open my $file, '<file1.txt' or die "$!";
while( <$file> ) { next if /$regex/; print }
close $file;
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$regex is created by first using qw to make a list of quoted words from the space-delimited exclusionary items. This list is passed to map which uses qq|\Q$_\E| to escape all special characters in each list item ($_ contains a list item). The results of map are joined with '|' for use as an or between the exclusionary items in the subsequent pattern match.

while we're reading each of the file's lines, if the pattern match finds an exclusionary item, the next line's requested, else the line's printed--both the matching and print operating on perl's default scaler: $_.

Hope this helps!