$EFFECTIVE_USER_ID

$DEBUGGING

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

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

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

$> The effective uid of this process. For example: $<

$OLD_PERL_VERSION

$^ The name of the current top-of-page format for the currently selected output channel. The default is the name of the filehandle with

$0 Contains the name of the program being executed. On some (but not all) operating systems assigning to

$[ This variable stores the index of the first element in an array, and of the first character in a substring. The default is 0, but you could