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
use VERSION and
require VERSION for a convenient way to fail if the running Perl interpreter is too old.
The use of this variable is deprecated. The floating point representation can sometimes lead to inaccurate numeric comparisons. See
$^V for a more modern representation of the Perl version that allows accurate string comparisons.