=over =item $PERL_VERSION =item $] The version + patchlevel / 1000 of the Perl interpreter. This variable can be used to determine whether the Perl interpreter executing a script is in the right range of versions. (Mnemonic: Is this version of perl in the right bracket?) Example: warn "No checksumming!\n" if $] < 3.019; See also the documentation of C and C for a convenient way to fail if the Perl interpreter is too old. =back