Handle '$LINENO'.

* geesh/lexer.scm (get-parameter-expansion): Include the current line
number with the variable name if it is 'LINENO'.
(call-with-metered-input-port): Set the line number of the soft port.
* geesh/word.scm (parameter-ref): Unpack the included line number when
the parameter name is 'LINENO'.

geesh/lexer.scm

@@ -309,11 +309,15 @@ leading '$')."
 (define (get-parameter-expansion port)
   "Get a parameter expansion (either '$name' or '${...}') from
 @var{port} (excluding the leading '$')."
-  (match (lookahead-char port)
-    (#\{ (get-parameter-expression port))
-    (_ (and=> (get-parameter port)
-              (lambda (name)
-                `(<sh-ref> ,name))))))
+  (let ((result (match (lookahead-char port)
+                  (#\{ (get-parameter-expression port))
+                  (_ (and=> (get-parameter port)
+                            (lambda (name)
+                              `(<sh-ref> ,name)))))))
+    (match result
+      ((op "LINENO") `(,op ("LINENO" . ,(1+ (port-line port)))))
+      ((op "LINENO" x) `(,op ("LINENO" . ,(1+ (port-line port))) ,x))
+      (_ result))))
 
 (define (get-bracketed-command port)
   "Get a bracketed command ('$(...)') from @var{port} (excluding the
@@ -479,6 +483,7 @@ characters read."
       ;; close-port
       #f)
      "r"))
+  (set-port-line! wrapped-port (port-line port))
   (let ((result (proc wrapped-port)))
     ;; The soft port seems to have an independent buffer from the
     ;; input port. This means that the "lookahead" character on the

geesh/word.scm

@@ -231,6 +231,7 @@ the environment.  If @var{name} is unset, return @code{#f}."
     ("#" (number->string (length (cdr (program-arguments)))))
     ("?" (number->string (get-status)))
     ("$" (number->string (get-root-pid)))
+    (("LINENO" . line) (number->string line))
     (x (let ((n (string->number x)))
          (if (and n (integer? n) (> n 0)
                   (<= n (length (cdr (program-arguments)))))