The English Module
English module helps you to deal with the confusing variable names, like $^X and $'.
English module associates the odd-named variables with something more understandable.
Variable English Usage
$^A $ACCUMULATOR Current value of write accumulator for format data.
$_ $ARG Default input and pattern-searching variable.
$^T $BASETIME Time script began running in time format.
$? $CHILD_ERROR Status returned by last pipe close or system function.
$^D $DEBUGGING Current value of Perl's debugging flags.
$) $EFFECTIVE_GROUP_ID Effective group ID for the Perl process.
$> $EFFECTIVE_USER_ID Effective user ID of process.
$^X $EXECUTABLE_NAME Name of Perl binary executable file
$! $ERRNO If numeric context, holds errno result of math function; if string context, holds error message. Also $OS_ERROR.
$@ $EVAL_ERROR Error message from last eval call.
$^E $EXTENDED_OS_ERROR Extended error on various operating systems. On Windows, holds the last error from the Win32 GetLastError() call.
$^L $FORMAT_FORMFEED Output to advance a page from write.
$: $FORMAT_LINE_BREAK_CHARACTERS Characters allowed to break on when filling continuation fields in a format.
$- $FORMAT_LINES_LEFT Number of lines left on current page.
$= $FORMAT_LINES_PER_PAGE Total number of lines available on page.
$~ $FORMAT_NAME Name of current format.
$% $FORMAT_PAGE_NUMBER Page number in current format.
$^ $FORMAT_TOP_NAME Name of top-of-page format.
$. $INPUT_LINE_NUMBER Line number in the last file handle that was read.
$/ $INPUT_RECORD_SEPARATOR Ends a line of text for input, newline on UNIX, carriage return and newline on Windows.
$+ $LAST_PAREN_MATCH Last bracket matched by last search.
$& $MATCH String matched by last match.
$# $OFMT Output format for numbers printed with print (not using the format command described in Chapter 5). Normally %.20g.
$^O $OSNAME Operating system name.
$| $OUTPUT_AUTOFLUSH If non-zero forces a flush with each write or print.
$, $OUTPUT_FIELD_SEPARATOR Output field separator.
$\ $OUTPUT_RECORD_SEPARATOR Output record separator, equivalent of $/ for output.
$^V $PERL_VERSION String printed by perl -v; version number.
$' $POSTMATCH String following last match.
$` $PREMATCH String preceding last match.
$$ $PROCESS_ID The process ID for this script. Also $PID.
$0 $PROGRAM_NAME Name of current Perl script (zero, not oh).
$( $REAL_GROUP_ID Group ID for the Perl process.
$< $REAL_USER_ID Real user ID.
$; $SUBSCRIPT_SEPARATOR Subscript separator for multi-dimensional arrays.
$^F $SYSTEM_FD_MAX Maximum system file descriptor.
$^W $WARNING True if warning is turned on (by perl -w); false otherwise.
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