@res = sort { int($a) <=> int($b) } <DATA>;
print foreach(@res);

__END__
34:dsfalk:as4
2:asd:3425
67:dfa:srkwej9
98:erwvrklj:sek

output -
2:asd:3425
34:dsfalk:as4
67:dfa:srkwej9
98:erwvrklj:sek