Special Variable AlillasMiscellaneous

$ - $ARG
@_ - @ARG
$" - $LIST-SEPARATOR
$; - $SUBSCRIPT_SEPARATOR or $SUBSEP

Regular Expression or pattern matching

$& - $MATCH
$' - $PREMATCH
$` - $POSTMATCH
$+ - $LAST_PAREN_MATCH

Input

$. - $INPUT_LINE_NUMBER or $NR
$/ - $INPUT_RECORD_SEPARATOR or $RS

Output

$I - $OUTPUT_AUTOFLUSH
$, - $OUTPUT_FIELD_SEPARATOR or $OFS
$\ - $OUTPUT_RECORD_SEPARATOR or $ORS

Formats

$% - $FORMAT_PAGE_NUMBER
$= - $FORMAT_LINES_PER_PAGE
$_ - $FORMAT_LINES_LEFT
$~ - $FORMAT_NAME
$^ - $FORMAT_TOP_NAME
$: - $FORMAT LINE BREAK_CHARACTERS
$^L - $FORMAT_FORMFEED

Error Status

$? - $CHILD_ERROR
$! - $OS_ERROR or $ERRNO
$@ - $EVAL_ERROR

Process Information

$$ - $PROCESS_ID or $PID
$< - $REAL_USER_ID or $UID
$> - $EFFECTIVE_USER_ID or $EUID
$( - $REAL_GROUP_ID or $GID
$) - $EFFECTIVE_GROUP_ID or $EGID
$0 - $PROGRAM_NAME

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