$^R The result of evaluation of the last successful (?{ code }) regular expression assertion (see

$PERLDB

@F The array @F contains the fields of each line read in when autosplit mode is turned on

$EFFECTIVE_GROUP_ID

${^RE_TRIE_MAXBUF} Controls how certain regex optimisations are applied and how much memory they utilize. This value by default is 65536 which

$SUBSEP

$^I The current value of the inplace-edit extension. Use

$FORMAT_PAGE_NUMBER

$! When referenced, $! retrieves the current value of the C

$CHILD_ERROR