$" When an array or an array slice is interpolated into a double-quoted string or a similar context such as /

${^PREMATCH} This is similar to $` ($PREMATCH) except that it does not incur the performance

@+ This array holds the offsets of the ends of the last successful submatches in the currently active dynamic scope.

$^W The current value of the warning switch, initially true if -w was used, false otherwise, but directly modifiable.

%ERRNO

%^H The %^H hash provides the same scoping semantic as

$OLD_PERL_VERSION

$$ The process number of the Perl running this script. Though you can set this variable, doing so is generally discouraged, although

$INPLACE_EDIT

$OUTPUT_FIELD_SEPARATOR