=over =item $OLD_PERL_VERSION =item $] X<$]> X<$OLD_PERL_VERSION> See L for a more modern representation of the Perl version that allows accurate string comparisons. 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: warn "No checksumming!\n" if $] < 3.019; The floating point representation can sometimes lead to inaccurate numeric comparisons. See also the documentation of C and C for a convenient way to fail if the running Perl interpreter is too old. Mnemonic: Is this version of perl in the right bracket? =back