$ARG

$<digits> ($1, $2, ...) Contains the subpattern from the corresponding set of capturing parentheses from the last successful pattern

$< The real uid of this process. You can change both the real uid and the effective uid at the same time by using

$` The string preceding whatever was matched by the last successful pattern match, not counting any matches hidden within a BLOCK or

${^UTF8CACHE} This variable controls the state of the internal UTF-8 offset caching code. 1 for on (the default), 0 for off, -1 to debug the

$^E Error information specific to the current operating system. At the moment, this differs from $!

$* $* was a variable that you could use to enable multiline matching. After a deprecation

$~ The name of the current report format for the currently selected output channel. The default format name is the same as the filehandle name

$. Current line number for the last filehandle accessed. Each filehandle in Perl counts the number of lines

@LAST_MATCH_START