use strict;
use warnings;

while (my $line = <DATA>) 
{
    my ($version) = $line =~ /^[a-z-]+(\d.*)\s*$/; 
    print ">>$version<<\n" if $version;   
}
=PRINTS:
>>2.10<<
>>2.10.2-r1<<
>>2.10.5<<
=cut

__DATA__
mono-basic-2.10
mono-2.10.2-r1
mono-2.10.5