feat(rc): added index operations

6 files changed, 358 insertions, 215 deletions

diff --git a/sys/cmd/rc/code.c b/sys/cmd/rc/code.c
index bcc3d38..0723279 100644
--- a/sys/cmd/rc/code.c
+++ b/sys/cmd/rc/code.c
@@ -72,6 +72,14 @@ walk(Tree *node)
         emitf(Xjoin);
         break;
 
+    case Tindex:
+        emitf(Xmark);
+        walk(node->child[1]);
+        emitf(Xmark);
+        walk(node->child[0]);
+        emitf(Xindex);
+        break;
+
     case ';':
         walk(node->child[0]);
         walk(node->child[1]);
diff --git a/sys/cmd/rc/exec.c b/sys/cmd/rc/exec.c
index e8d59c1..fbcfb9b 100644
--- a/sys/cmd/rc/exec.c
+++ b/sys/cmd/rc/exec.c
@@ -703,6 +703,119 @@ Xconcatenate(void)
 }
 
 void
+Xdollar(void)
+{
+    int n;
+    char *s, *t;
+    Word *a, *star;
+
+    if(count(runner->args->word)!=1){
+        Xerror("variable name not singleton!\n");
+        return;
+    }
+    s = runner->args->word->str;
+    // deglob(s);
+    n = 0;
+
+    for(t = s;'0'<=*t && *t<='9';t++) 
+        n = n*10+*t-'0';
+
+    a = runner->args->link->word;
+
+    if(n==0 || *t)
+        a = copywords(var(s)->val, a);
+    else{
+        star = var("*")->val;
+        if(star && 1<=n && n<=count(star)){
+            while(--n)
+                star = star->link;
+
+            a = makeword(star->str, a);
+        }
+    }
+
+    poplist();
+    runner->args->word = a;
+}
+
+static
+Word*
+cpwords(Word *array, Word *tail, int n)
+{
+    Word *cp, **end;
+
+    cp = nil, end = &cp;
+    while(n-- > 0){
+        *end = makeword(array->str, nil);
+        end = &(*end)->link;
+        array = array->link;
+    }
+    *end = tail;
+
+    return cp;
+}
+
+
+static
+Word*
+getindex(Word *array, int len, Word *index, Word *tail)
+{
+    char *s;
+    int n, m;
+    if(!index)
+        return tail;
+
+    tail = getindex(array, len, index->link, tail);
+
+    s = index->str;
+    //deglob(s)
+
+    m = 0, n = 0;
+    while('0' <= *s && *s <= '9')
+        n = 10*n + (*s++ - '0');
+    if(*s == '-'){
+        if(*++s == 0)
+            m = len - n;
+        else{
+            while('0' <= *s && *s <= '9')
+                m = 10*m + (*s++ - '0');
+            m -= n;
+        }
+    }
+
+    if(n<1 || n > len || m < 0)
+        return tail;
+    if(n+m > len)
+        m = len-n;
+    while(--n > 0)
+        array = array->link;
+    return cpwords(array, tail, m+1);
+}
+
+void
+Xindex(void)
+{
+    char *s;
+    Word *val, *ret;
+
+    if(count(runner->args->word) != 1){
+        Xerror("variable name not a singleton");
+        return;
+    }
+    s = runner->args->word->str;
+    //deglob(s)
+    val = var(s)->val;
+    poplist();
+
+    ret = runner->args->link->word; // pointer to next stack frame
+    ret = getindex(val, count(val), runner->args->word, ret);
+    poplist();
+
+    // push result back on stack
+    runner->args->word = ret;
+}
+
+void
 Xjoin(void)
 {
     int  n;
@@ -744,42 +857,6 @@ Xjoin(void)
 }
 
 void
-Xdollar(void)
-{
-    int n;
-    char *s, *t;
-    Word *a, *star;
-
-    if(count(runner->args->word)!=1){
-        Xerror("variable name not singleton!\n");
-        return;
-    }
-    s = runner->args->word->str;
-    // deglob(s);
-    n = 0;
-
-    for(t = s;'0'<=*t && *t<='9';t++) 
-        n = n*10+*t-'0';
-
-    a = runner->args->link->word;
-
-    if(n==0 || *t)
-        a = copywords(var(s)->val, a);
-    else{
-        star = var("*")->val;
-        if(star && 1<=n && n<=count(star)){
-            while(--n)
-                star = star->link;
-
-            a = makeword(star->str, a);
-        }
-    }
-
-    poplist();
-    runner->args->word = a;
-}
-
-void
 Xassign(void)
 {
     Var *v;
diff --git a/sys/cmd/rc/exec.h b/sys/cmd/rc/exec.h
index 9edd9ed..635eb1d 100644
--- a/sys/cmd/rc/exec.h
+++ b/sys/cmd/rc/exec.h
@@ -2,24 +2,23 @@
 
 /*
  * opcode routines
- * Arguments on stack (...)
- * Arguments in line [...]
- * Code in line with jump around {...}
+ * arguments on stack (...)
+ * arguments in line [...]
+ * code in line with jump around {...}
  */
 
-void Xtrue(void);
-void Xfalse(void);
-void Xdollar(void);
-void Xexit(void);
-void Xmark(void);
-void Xreturn(void);
-void Xlocal(void);
-void Xreadcmd(void);
-void Xunlocal(void);
+void Xmark(void);           // Xmark            marks stack location for word
+void Xtrue(void);           // Xtrue{...}       execute {} if true
+void Xfalse(void);          // Xfalse{...}      execute {} if false
+void Xdollar(void);         // Xdollar(name)    get value of name
+void Xindex(void);          // Xindex
+void Xlocal(void);          // Xlocal(name,val) create local variable, assign value
+void Xunlocal(void);        // Xunlocal         delete local variable
+void Xreadcmd(void);        //
 void Xassign(void);
 void Xbang(void);
 void Xasync(void);
-void Xbasic(void);     // Xbasic(args) run command and wait for result
+void Xbasic(void);          // Xbasic(args) run command and wait for result
 void Xsubshell(void);
 void Xword(void);
 void Xjoin(void);
@@ -30,6 +29,9 @@ void Xpipe(void);
 void Xpipewait(void);
 void Xpopredir(void);
 
+void Xreturn(void);
+void Xexit(void);
+
 void Xerror(char*);
 
 /* builtin commands */
diff --git a/sys/cmd/rc/main.c b/sys/cmd/rc/main.c
index 3f2e02e..9e35a87 100644
--- a/sys/cmd/rc/main.c
+++ b/sys/cmd/rc/main.c
@@ -60,4 +60,5 @@ main(int argc, char *argv[])
 
     // enablevi();
     xboot(argc, argv);
+    /* unreachable */
 }
diff --git a/sys/cmd/rc/parse.c b/sys/cmd/rc/parse.c
index 774e8d4..687956b 100644
--- a/sys/cmd/rc/parse.c
+++ b/sys/cmd/rc/parse.c
@@ -139,27 +139,29 @@ enum yysymbol_kind_t
   YYSYMBOL_34_ = 34,                       /* ';'  */
   YYSYMBOL_35_ = 35,                       /* '&'  */
   YYSYMBOL_36_ = 36,                       /* '='  */
-  YYSYMBOL_YYACCEPT = 37,                  /* $accept  */
-  YYSYMBOL_rc = 38,                        /* rc  */
-  YYSYMBOL_line = 39,                      /* line  */
-  YYSYMBOL_body = 40,                      /* body  */
-  YYSYMBOL_paren = 41,                     /* paren  */
-  YYSYMBOL_block = 42,                     /* block  */
-  YYSYMBOL_cmds = 43,                      /* cmds  */
-  YYSYMBOL_cmdsln = 44,                    /* cmdsln  */
-  YYSYMBOL_ifbody = 45,                    /* ifbody  */
-  YYSYMBOL_assign = 46,                    /* assign  */
-  YYSYMBOL_redir = 47,                     /* redir  */
-  YYSYMBOL_epilog = 48,                    /* epilog  */
-  YYSYMBOL_cmd = 49,                       /* cmd  */
-  YYSYMBOL_basic = 50,                     /* basic  */
-  YYSYMBOL_atom = 51,                      /* atom  */
-  YYSYMBOL_word = 52,                      /* word  */
-  YYSYMBOL_executable = 53,                /* executable  */
-  YYSYMBOL_nonkeyword = 54,                /* nonkeyword  */
-  YYSYMBOL_keyword = 55,                   /* keyword  */
-  YYSYMBOL_wordsnl = 56,                   /* wordsnl  */
-  YYSYMBOL_nl = 57                         /* nl  */
+  YYSYMBOL_37_ = 37,                       /* '`'  */
+  YYSYMBOL_YYACCEPT = 38,                  /* $accept  */
+  YYSYMBOL_rc = 39,                        /* rc  */
+  YYSYMBOL_line = 40,                      /* line  */
+  YYSYMBOL_body = 41,                      /* body  */
+  YYSYMBOL_paren = 42,                     /* paren  */
+  YYSYMBOL_block = 43,                     /* block  */
+  YYSYMBOL_cmds = 44,                      /* cmds  */
+  YYSYMBOL_cmdsln = 45,                    /* cmdsln  */
+  YYSYMBOL_ifbody = 46,                    /* ifbody  */
+  YYSYMBOL_assign = 47,                    /* assign  */
+  YYSYMBOL_redir = 48,                     /* redir  */
+  YYSYMBOL_epilog = 49,                    /* epilog  */
+  YYSYMBOL_cmd = 50,                       /* cmd  */
+  YYSYMBOL_basic = 51,                     /* basic  */
+  YYSYMBOL_atom = 52,                      /* atom  */
+  YYSYMBOL_word = 53,                      /* word  */
+  YYSYMBOL_executable = 54,                /* executable  */
+  YYSYMBOL_nonkeyword = 55,                /* nonkeyword  */
+  YYSYMBOL_keyword = 56,                   /* keyword  */
+  YYSYMBOL_words = 57,                     /* words  */
+  YYSYMBOL_wordsnl = 58,                   /* wordsnl  */
+  YYSYMBOL_nl = 59                         /* nl  */
 };
 typedef enum yysymbol_kind_t yysymbol_kind_t;
 
@@ -485,18 +487,18 @@ union yyalloc
 #endif /* !YYCOPY_NEEDED */
 
 /* YYFINAL -- State number of the termination state.  */
-#define YYFINAL  47
+#define YYFINAL  49
 /* YYLAST -- Last index in YYTABLE.  */
-#define YYLAST   195
+#define YYLAST   290
 
 /* YYNTOKENS -- Number of terminals.  */
-#define YYNTOKENS  37
+#define YYNTOKENS  38
 /* YYNNTS -- Number of nonterminals.  */
-#define YYNNTS  21
+#define YYNNTS  22
 /* YYNRULES -- Number of rules.  */
-#define YYNRULES  59
+#define YYNRULES  63
 /* YYNSTATES -- Number of states.  */
-#define YYNSTATES  90
+#define YYNSTATES  96
 
 /* YYMAXUTOK -- Last valid token kind.  */
 #define YYMAXUTOK   281
@@ -522,7 +524,7 @@ static const yytype_int8 yytranslate[] =
        2,    36,     2,     2,     2,     2,     2,     2,     2,     2,
        2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
        2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
-       2,     2,     2,     2,    27,     2,     2,     2,     2,     2,
+       2,     2,     2,     2,    27,     2,    37,     2,     2,     2,
        2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
        2,     2,     2,     2,     2,     2,     2,     2,     2,     2,
        2,     2,     2,    32,     2,    33,     2,     2,     2,     2,
@@ -552,8 +554,9 @@ static const yytype_uint8 yyrline[] =
       56,    57,    60,    61,    64,    65,    68,    71,    72,    75,
       76,    79,    80,    81,    82,    83,    84,    85,    86,    87,
       88,    89,    92,    93,    94,    97,    98,   101,   102,   105,
-     106,   109,   110,   111,   112,   113,   117,   117,   117,   117,
-     117,   117,   117,   117,   117,   124,   125,   126,   128,   130
+     106,   109,   110,   111,   112,   113,   114,   115,   120,   120,
+     120,   120,   120,   120,   120,   120,   120,   123,   124,   127,
+     128,   129,   131,   133
 };
 #endif
 
@@ -574,9 +577,9 @@ static const char *const yytname[] =
   "Tfunc", "Tredir", "Tdup", "Tpipe", "Tindex", "Tbasic", "Targs", "Tword",
   "Twords", "Tparen", "Tblock", "')'", "Tandand", "Toror", "'\\n'", "'^'",
   "'$'", "Tcount", "Tjoin", "'('", "'{'", "'}'", "';'", "'&'", "'='",
-  "$accept", "rc", "line", "body", "paren", "block", "cmds", "cmdsln",
-  "ifbody", "assign", "redir", "epilog", "cmd", "basic", "atom", "word",
-  "executable", "nonkeyword", "keyword", "wordsnl", "nl", YY_NULLPTR
+  "'`'", "$accept", "rc", "line", "body", "paren", "block", "cmds",
+  "cmdsln", "ifbody", "assign", "redir", "epilog", "cmd", "basic", "atom",
+  "word", "executable", "nonkeyword", "keyword", "words", "wordsnl", "nl", YY_NULLPTR
 };
 
 static const char *
@@ -586,7 +589,7 @@ yysymbol_name (yysymbol_kind_t yysymbol)
 }
 #endif
 
-#define YYPACT_NINF (-34)
+#define YYPACT_NINF (-46)
 
 #define yypact_value_is_default(Yyn) \
   ((Yyn) == YYPACT_NINF)
@@ -600,15 +603,16 @@ yysymbol_name (yysymbol_kind_t yysymbol)
    STATE-NUM.  */
 static const yytype_int16 yypact[] =
 {
-      70,   -24,   163,   163,   129,   -34,   -34,   129,   129,   129,
-     -34,   163,    26,     2,    38,   163,   163,   163,    62,    27,
-      17,   -34,   163,   -34,    30,    30,   -34,   -34,   -34,   -34,
-     -34,   -34,   -34,   -34,   -34,   -34,    21,   -34,   -34,   -34,
-     -34,   -34,   100,    16,   -34,   163,   146,   -34,   -34,    38,
-     -34,   -34,    30,    30,   -34,   -34,   -34,   -34,   -34,   -34,
-      21,   129,   129,    45,   136,   129,   -34,   -34,    21,   -34,
-     -34,   -34,   -34,   136,   136,   136,   -34,    21,   -34,   -34,
-      11,   -34,    35,   -34,   -34,    30,    30,   -34,   136,    35
+      22,   -17,   253,   253,   197,   -46,   -46,   197,   197,   197,
+     -46,   253,   -13,    45,    23,    49,   253,   253,   253,    57,
+      92,     7,   -46,   253,   -46,    40,    40,   -46,   -46,   -46,
+     -46,   -46,   -46,   -46,   -46,   -46,   -46,    31,   -46,   -46,
+      44,   -46,   -46,   127,    37,   -46,   253,     5,   -46,   -46,
+     -46,    49,   -46,   -46,    40,    40,   -46,   -46,   -46,   -46,
+     -46,   -46,    31,   197,   197,    52,   225,   197,   -46,   -46,
+     -46,    31,   -46,   -46,   -46,   -46,   225,   225,   225,   -46,
+      31,   -46,   -46,    60,   -46,    32,   -46,   162,   -46,    40,
+      40,   -46,   -46,    31,   225,    32
 };
 
 /* YYDEFACT[STATE-NUM] -- Default reduction number in state STATE-NUM.
@@ -617,30 +621,31 @@ static const yytype_int16 yypact[] =
 static const yytype_int8 yydefact[] =
 {
       21,     0,    21,    21,     0,    17,    41,     0,     0,     0,
-      55,    21,     0,     0,    19,    21,    21,    21,     4,    22,
-      32,    39,    21,    58,    29,    30,    47,    46,    48,    49,
-      50,    51,    52,    53,    54,    37,    18,    35,    36,    42,
-      44,    45,     0,     0,    12,    21,     6,     1,     3,    19,
-      23,     5,    28,    27,    58,    58,    58,    10,    11,    34,
-      33,     0,     0,     0,    21,     0,    43,    56,    57,     9,
-       7,    13,    20,    21,    21,    21,    40,    16,     8,    59,
-      19,    31,    14,    38,    24,    25,    26,    58,    21,    15
+      59,    21,     0,     0,     0,    19,    21,    21,    21,     4,
+      22,    32,    39,    21,    62,    29,    30,    49,    48,    50,
+      51,    52,    53,    54,    55,    56,    37,    18,    35,    36,
+      42,    45,    46,     0,     0,    12,    21,     6,    47,     1,
+       3,    19,    23,     5,    28,    27,    62,    62,    62,    10,
+      11,    34,    33,     0,     0,     0,    21,     0,    57,    44,
+      60,    61,     9,     7,    13,    20,    21,    21,    21,    40,
+      16,     8,    63,    19,    31,    14,    38,     0,    24,    25,
+      26,    62,    43,    58,    21,    15
 };
 
 /* YYPGOTO[NTERM-NUM].  */
 static const yytype_int8 yypgoto[] =
 {
-     -34,   -34,    46,    -3,   -34,     7,    14,   -34,   -34,   -34,
-     -13,    23,     0,   -34,     4,   -15,   -34,     1,   -34,   -34,
-     -33
+     -46,   -46,    64,    -8,   -46,    -5,    26,   -46,   -46,   -46,
+     -14,    33,     0,   -46,    16,   -16,   -46,     1,   -46,   -46,
+     -46,   -45
 };
 
 /* YYDEFGOTO[NTERM-NUM].  */
 static const yytype_int8 yydefgoto[] =
 {
-       0,    12,    13,    43,    23,    14,    44,    45,    81,    16,
-      17,    50,    46,    19,    35,    36,    20,    21,    38,    42,
-      64
+       0,    13,    14,    44,    24,    15,    45,    46,    84,    17,
+      18,    52,    47,    20,    36,    37,    21,    22,    39,    87,
+      43,    66
 };
 
 /* YYTABLE[YYPACT[STATE-NUM]] -- What to do in state STATE-NUM.  If
@@ -648,50 +653,70 @@ static const yytype_int8 yydefgoto[] =
    number is the opposite.  If YYTABLE_NINF, syntax error.  */
 static const yytype_int8 yytable[] =
 {
-      18,    49,    24,    25,    60,    37,    59,    22,    37,    37,
-      37,    39,    40,    41,    15,    18,    52,    53,    87,    63,
-      37,    73,    74,    75,     4,     5,    47,    68,    48,    15,
-      26,    27,    28,    29,    30,    31,    49,    32,    33,    34,
-       4,     5,    70,    37,    61,    54,     6,    77,    65,    69,
-      54,     4,     5,    62,    88,     7,     8,     9,    10,    55,
-      56,    51,    37,    37,    82,    76,    37,    49,    78,    83,
-      -2,    80,    72,    84,    85,    86,     1,    54,     0,     0,
-       2,     3,     0,     4,     5,     0,    55,    56,    89,     6,
-       0,     0,     0,     0,     0,     0,    57,    58,     7,     8,
-       9,    10,    11,    26,    27,    28,    29,    30,    31,     0,
-      32,    33,    34,     0,     0,     0,     0,     0,     0,     6,
-       0,     0,     0,    66,     0,     0,    67,     0,     7,     8,
-       9,    10,    26,    27,    28,    29,    30,    31,     0,    32,
-      33,    34,     1,     0,     0,     0,     2,     3,     6,     4,
-       5,     0,     0,     0,     0,     6,     0,     7,     8,     9,
-      10,    54,    79,     0,     7,     8,     9,    10,    11,     1,
-      55,    56,    71,     2,     3,     0,     4,     5,     0,     0,
-      57,    58,     6,     0,     0,     0,     0,     0,     0,     0,
-       0,     7,     8,     9,    10,    11
+      19,    51,    25,    26,    62,    38,    61,    48,    38,    38,
+      38,    76,    77,    78,    23,    65,    19,    54,    55,    11,
+      56,    38,    -2,    40,    41,    42,    16,    71,     1,    57,
+      58,    74,     2,     3,    63,     4,     5,    51,    73,    59,
+      60,     6,    16,    64,    38,    49,    94,    56,    80,    50,
+       7,     8,     9,    10,    11,    56,    57,    58,    67,    12,
+      68,    83,     4,     5,    38,    38,    85,    91,    38,    51,
+      72,    93,    56,     4,     5,    81,    88,    89,    90,    79,
+      53,    57,    58,    86,    75,     0,     0,     0,    38,     0,
+       0,    59,    60,     0,    95,    27,    28,    29,    30,    31,
+      32,     0,    33,    34,    35,     4,     5,     0,     0,     0,
+       0,     6,     0,     0,     0,     0,     0,     0,     0,     0,
+       7,     8,     9,    10,     0,     0,     0,     0,     0,    12,
+      27,    28,    29,    30,    31,    32,     0,    33,    34,    35,
+       0,     0,     0,     0,     0,     0,     6,     0,     0,     0,
+      69,     0,     0,    70,     0,     7,     8,     9,    10,     0,
+       0,     0,     0,     0,    12,    27,    28,    29,    30,    31,
+      32,     0,    33,    34,    35,     0,     0,     0,     0,     0,
+       0,     6,     0,     0,     0,    92,     0,     0,     0,     0,
+       7,     8,     9,    10,     0,     0,     0,     0,     0,    12,
+      27,    28,    29,    30,    31,    32,     0,    33,    34,    35,
+       0,     0,     0,     0,     0,     0,     6,     0,     0,     0,
+       0,     0,     0,     0,     0,     7,     8,     9,    10,     0,
+       0,     1,     0,     0,    12,     2,     3,     0,     4,     5,
+       0,     0,     0,     0,     6,     0,     0,     0,     0,     0,
+       0,    82,     0,     7,     8,     9,    10,    11,     0,     1,
+       0,     0,    12,     2,     3,     0,     4,     5,     0,     0,
+       0,     0,     6,     0,     0,     0,     0,     0,     0,     0,
+       0,     7,     8,     9,    10,    11,     0,     0,     0,     0,
+      12
 };
 
 static const yytype_int8 yycheck[] =
 {
-       0,    14,     2,     3,    19,     4,    19,    31,     7,     8,
-       9,     7,     8,     9,     0,    15,    16,    17,     7,    22,
-      19,    54,    55,    56,    13,    14,     0,    42,    26,    15,
-       3,     4,     5,     6,     7,     8,    49,    10,    11,    12,
-      13,    14,    45,    42,    27,    15,    19,    62,    27,    33,
-      15,    13,    14,    36,    87,    28,    29,    30,    31,    24,
-      25,    15,    61,    62,    64,    61,    65,    80,    23,    65,
-       0,    64,    49,    73,    74,    75,     6,    15,    -1,    -1,
-      10,    11,    -1,    13,    14,    -1,    24,    25,    88,    19,
-      -1,    -1,    -1,    -1,    -1,    -1,    34,    35,    28,    29,
-      30,    31,    32,     3,     4,     5,     6,     7,     8,    -1,
-      10,    11,    12,    -1,    -1,    -1,    -1,    -1,    -1,    19,
-      -1,    -1,    -1,    23,    -1,    -1,    26,    -1,    28,    29,
-      30,    31,     3,     4,     5,     6,     7,     8,    -1,    10,
-      11,    12,     6,    -1,    -1,    -1,    10,    11,    19,    13,
-      14,    -1,    -1,    -1,    -1,    19,    -1,    28,    29,    30,
-      31,    15,    26,    -1,    28,    29,    30,    31,    32,     6,
-      24,    25,    26,    10,    11,    -1,    13,    14,    -1,    -1,
-      34,    35,    19,    -1,    -1,    -1,    -1,    -1,    -1,    -1,
-      -1,    28,    29,    30,    31,    32
+       0,    15,     2,     3,    20,     4,    20,    12,     7,     8,
+       9,    56,    57,    58,    31,    23,    16,    17,    18,    32,
+      15,    20,     0,     7,     8,     9,     0,    43,     6,    24,
+      25,    26,    10,    11,    27,    13,    14,    51,    46,    34,
+      35,    19,    16,    36,    43,     0,    91,    15,    64,    26,
+      28,    29,    30,    31,    32,    15,    24,    25,    27,    37,
+      16,    66,    13,    14,    63,    64,    66,     7,    67,    83,
+      33,    87,    15,    13,    14,    23,    76,    77,    78,    63,
+      16,    24,    25,    67,    51,    -1,    -1,    -1,    87,    -1,
+      -1,    34,    35,    -1,    94,     3,     4,     5,     6,     7,
+       8,    -1,    10,    11,    12,    13,    14,    -1,    -1,    -1,
+      -1,    19,    -1,    -1,    -1,    -1,    -1,    -1,    -1,    -1,
+      28,    29,    30,    31,    -1,    -1,    -1,    -1,    -1,    37,
+       3,     4,     5,     6,     7,     8,    -1,    10,    11,    12,
+      -1,    -1,    -1,    -1,    -1,    -1,    19,    -1,    -1,    -1,
+      23,    -1,    -1,    26,    -1,    28,    29,    30,    31,    -1,
+      -1,    -1,    -1,    -1,    37,     3,     4,     5,     6,     7,
+       8,    -1,    10,    11,    12,    -1,    -1,    -1,    -1,    -1,
+      -1,    19,    -1,    -1,    -1,    23,    -1,    -1,    -1,    -1,
+      28,    29,    30,    31,    -1,    -1,    -1,    -1,    -1,    37,
+       3,     4,     5,     6,     7,     8,    -1,    10,    11,    12,
+      -1,    -1,    -1,    -1,    -1,    -1,    19,    -1,    -1,    -1,
+      -1,    -1,    -1,    -1,    -1,    28,    29,    30,    31,    -1,
+      -1,     6,    -1,    -1,    37,    10,    11,    -1,    13,    14,
+      -1,    -1,    -1,    -1,    19,    -1,    -1,    -1,    -1,    -1,
+      -1,    26,    -1,    28,    29,    30,    31,    32,    -1,     6,
+      -1,    -1,    37,    10,    11,    -1,    13,    14,    -1,    -1,
+      -1,    -1,    19,    -1,    -1,    -1,    -1,    -1,    -1,    -1,
+      -1,    28,    29,    30,    31,    32,    -1,    -1,    -1,    -1,
+      37
 };
 
 /* YYSTOS[STATE-NUM] -- The symbol kind of the accessing symbol of
@@ -699,25 +724,27 @@ static const yytype_int8 yycheck[] =
 static const yytype_int8 yystos[] =
 {
        0,     6,    10,    11,    13,    14,    19,    28,    29,    30,
-      31,    32,    38,    39,    42,    43,    46,    47,    49,    50,
-      53,    54,    31,    41,    49,    49,     3,     4,     5,     6,
-       7,     8,    10,    11,    12,    51,    52,    54,    55,    51,
-      51,    51,    56,    40,    43,    44,    49,     0,    26,    47,
-      48,    39,    49,    49,    15,    24,    25,    34,    35,    47,
-      52,    27,    36,    40,    57,    27,    23,    26,    52,    33,
-      40,    26,    48,    57,    57,    57,    51,    52,    23,    26,
-      42,    45,    49,    51,    49,    49,    49,     7,    57,    49
+      31,    32,    37,    39,    40,    43,    44,    47,    48,    50,
+      51,    54,    55,    31,    42,    50,    50,     3,     4,     5,
+       6,     7,     8,    10,    11,    12,    52,    53,    55,    56,
+      52,    52,    52,    58,    41,    44,    45,    50,    43,     0,
+      26,    48,    49,    40,    50,    50,    15,    24,    25,    34,
+      35,    48,    53,    27,    36,    41,    59,    27,    16,    23,
+      26,    53,    33,    41,    26,    49,    59,    59,    59,    52,
+      53,    23,    26,    43,    46,    50,    52,    57,    50,    50,
+      50,     7,    23,    53,    59,    50
 };
 
 /* YYR1[RULE-NUM] -- Symbol kind of the left-hand side of rule RULE-NUM.  */
 static const yytype_int8 yyr1[] =
 {
-       0,    37,    38,    38,    39,    39,    40,    40,    41,    42,
-      43,    43,    44,    44,    45,    45,    46,    47,    47,    48,
-      48,    49,    49,    49,    49,    49,    49,    49,    49,    49,
-      49,    49,    50,    50,    50,    51,    51,    52,    52,    53,
-      53,    54,    54,    54,    54,    54,    55,    55,    55,    55,
-      55,    55,    55,    55,    55,    56,    56,    56,    57,    57
+       0,    38,    39,    39,    40,    40,    41,    41,    42,    43,
+      44,    44,    45,    45,    46,    46,    47,    48,    48,    49,
+      49,    50,    50,    50,    50,    50,    50,    50,    50,    50,
+      50,    50,    51,    51,    51,    52,    52,    53,    53,    54,
+      54,    55,    55,    55,    55,    55,    55,    55,    56,    56,
+      56,    56,    56,    56,    56,    56,    56,    57,    57,    58,
+      58,    58,    59,    59
 };
 
 /* YYR2[RULE-NUM] -- Number of symbols on the right-hand side of rule RULE-NUM.  */
@@ -727,8 +754,9 @@ static const yytype_int8 yyr2[] =
        2,     2,     1,     2,     1,     4,     3,     1,     2,     0,
        2,     0,     1,     2,     4,     4,     4,     2,     2,     2,
        2,     4,     1,     2,     2,     1,     1,     1,     3,     1,
-       3,     1,     2,     3,     2,     2,     1,     1,     1,     1,
-       1,     1,     1,     1,     1,     0,     2,     2,     0,     2
+       3,     1,     2,     5,     3,     2,     2,     2,     1,     1,
+       1,     1,     1,     1,     1,     1,     1,     0,     2,     0,
+       2,     2,     0,     2
 };
 
 
@@ -1464,215 +1492,239 @@ yyreduce:
   case 2: /* rc: %empty  */
 #line 38 "sys/cmd/rc/syntax.y"
             { return 0; }
-#line 1468 "sys/cmd/rc/parse.c"
+#line 1496 "sys/cmd/rc/parse.c"
     break;
 
   case 3: /* rc: line '\n'  */
 #line 39 "sys/cmd/rc/syntax.y"
             { return compile((yyvsp[-1].tree)); }
-#line 1474 "sys/cmd/rc/parse.c"
+#line 1502 "sys/cmd/rc/parse.c"
     break;
 
   case 5: /* line: cmds line  */
 #line 43 "sys/cmd/rc/syntax.y"
             { (yyval.tree) = maketree2(';', (yyvsp[-1].tree), (yyvsp[0].tree)); }
-#line 1480 "sys/cmd/rc/parse.c"
+#line 1508 "sys/cmd/rc/parse.c"
     break;
 
   case 7: /* body: cmdsln body  */
 #line 47 "sys/cmd/rc/syntax.y"
               { (yyval.tree) = maketree2(';', (yyvsp[-1].tree), (yyvsp[0].tree)); }
-#line 1486 "sys/cmd/rc/parse.c"
+#line 1514 "sys/cmd/rc/parse.c"
     break;
 
   case 8: /* paren: '(' body ')'  */
 #line 50 "sys/cmd/rc/syntax.y"
                { (yyval.tree) = maketree1(Tparen, (yyvsp[-1].tree)); }
-#line 1492 "sys/cmd/rc/parse.c"
+#line 1520 "sys/cmd/rc/parse.c"
     break;
 
   case 9: /* block: '{' body '}'  */
 #line 53 "sys/cmd/rc/syntax.y"
                { (yyval.tree) = maketree1(Tblock, (yyvsp[-1].tree)); }
-#line 1498 "sys/cmd/rc/parse.c"
+#line 1526 "sys/cmd/rc/parse.c"
     break;
 
   case 11: /* cmds: cmd '&'  */
 #line 57 "sys/cmd/rc/syntax.y"
           { (yyval.tree) = maketree1('&', (yyvsp[-1].tree)); }
-#line 1504 "sys/cmd/rc/parse.c"
+#line 1532 "sys/cmd/rc/parse.c"
     break;
 
   case 14: /* ifbody: cmd  */
 #line 64 "sys/cmd/rc/syntax.y"
                      { (yyval.tree) = maketree2(Tif, nil, (yyvsp[0].tree)); }
-#line 1510 "sys/cmd/rc/parse.c"
+#line 1538 "sys/cmd/rc/parse.c"
     break;
 
   case 15: /* ifbody: block Telse nl cmd  */
 #line 65 "sys/cmd/rc/syntax.y"
                      { (yyval.tree) = maketree3(Tif, nil, (yyvsp[-3].tree), (yyvsp[-2].tree)); }
-#line 1516 "sys/cmd/rc/parse.c"
+#line 1544 "sys/cmd/rc/parse.c"
     break;
 
   case 16: /* assign: executable '=' word  */
 #line 68 "sys/cmd/rc/syntax.y"
                         { (yyval.tree) = maketree2('=', (yyvsp[-2].tree), (yyvsp[0].tree)); }
-#line 1522 "sys/cmd/rc/parse.c"
+#line 1550 "sys/cmd/rc/parse.c"
     break;
 
   case 18: /* redir: Tredir word  */
 #line 72 "sys/cmd/rc/syntax.y"
                            { (yyval.tree) = hangchild1((yyvsp[-1].tree), (yyvsp[0].tree), 0); }
-#line 1528 "sys/cmd/rc/parse.c"
+#line 1556 "sys/cmd/rc/parse.c"
     break;
 
   case 19: /* epilog: %empty  */
 #line 75 "sys/cmd/rc/syntax.y"
                 { (yyval.tree) = nil; }
-#line 1534 "sys/cmd/rc/parse.c"
+#line 1562 "sys/cmd/rc/parse.c"
     break;
 
   case 20: /* epilog: redir epilog  */
 #line 76 "sys/cmd/rc/syntax.y"
                 { (yyval.tree) = hangchild1((yyvsp[-1].tree), (yyvsp[0].tree), 1); }
-#line 1540 "sys/cmd/rc/parse.c"
+#line 1568 "sys/cmd/rc/parse.c"
     break;
 
   case 21: /* cmd: %empty  */
 #line 79 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = nil; }
-#line 1546 "sys/cmd/rc/parse.c"
+#line 1574 "sys/cmd/rc/parse.c"
     break;
 
   case 22: /* cmd: basic  */
 #line 80 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = maketree1(Tbasic, (yyvsp[0].tree)); }
-#line 1552 "sys/cmd/rc/parse.c"
+#line 1580 "sys/cmd/rc/parse.c"
     break;
 
   case 23: /* cmd: block epilog  */
 #line 81 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = hangepilog((yyvsp[-1].tree), (yyvsp[0].tree)); }
-#line 1558 "sys/cmd/rc/parse.c"
+#line 1586 "sys/cmd/rc/parse.c"
     break;
 
   case 24: /* cmd: cmd Tpipe nl cmd  */
 #line 82 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = hangchild2((yyvsp[-2].tree), (yyvsp[-3].tree), 0, (yyvsp[0].tree), 1); }
-#line 1564 "sys/cmd/rc/parse.c"
+#line 1592 "sys/cmd/rc/parse.c"
     break;
 
   case 25: /* cmd: cmd Tandand nl cmd  */
 #line 83 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = maketree2(Tandand, (yyvsp[-3].tree), (yyvsp[0].tree)); }
-#line 1570 "sys/cmd/rc/parse.c"
+#line 1598 "sys/cmd/rc/parse.c"
     break;
 
   case 26: /* cmd: cmd Toror nl cmd  */
 #line 84 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = maketree2(Toror, (yyvsp[-3].tree), (yyvsp[0].tree)); }
-#line 1576 "sys/cmd/rc/parse.c"
+#line 1604 "sys/cmd/rc/parse.c"
     break;
 
   case 27: /* cmd: redir cmd  */
 #line 85 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = hangchild1((yyvsp[-1].tree), (yyvsp[0].tree), 1); }
-#line 1582 "sys/cmd/rc/parse.c"
+#line 1610 "sys/cmd/rc/parse.c"
     break;
 
   case 28: /* cmd: assign cmd  */
 #line 86 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = hangchild1((yyvsp[-1].tree), (yyvsp[0].tree), 2); }
-#line 1588 "sys/cmd/rc/parse.c"
+#line 1616 "sys/cmd/rc/parse.c"
     break;
 
   case 29: /* cmd: Tbang cmd  */
 #line 87 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = maketree1(Tbang, (yyvsp[0].tree)); }
-#line 1594 "sys/cmd/rc/parse.c"
+#line 1622 "sys/cmd/rc/parse.c"
     break;
 
   case 30: /* cmd: Tsubshell cmd  */
 #line 88 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = maketree1(Tsubshell, (yyvsp[0].tree)); }
-#line 1600 "sys/cmd/rc/parse.c"
+#line 1628 "sys/cmd/rc/parse.c"
     break;
 
   case 31: /* cmd: Tif paren nl ifbody  */
 #line 89 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = hangchild1((yyvsp[-2].tree), (yyvsp[-3].tree), 0); }
-#line 1606 "sys/cmd/rc/parse.c"
+#line 1634 "sys/cmd/rc/parse.c"
     break;
 
   case 33: /* basic: basic word  */
 #line 93 "sys/cmd/rc/syntax.y"
                 { (yyval.tree) = maketree2(Targs, (yyvsp[-1].tree), (yyvsp[0].tree)); }
-#line 1612 "sys/cmd/rc/parse.c"
+#line 1640 "sys/cmd/rc/parse.c"
     break;
 
   case 34: /* basic: basic redir  */
 #line 94 "sys/cmd/rc/syntax.y"
                 { (yyval.tree) = maketree2(Targs, (yyvsp[-1].tree), (yyvsp[0].tree)); }
-#line 1618 "sys/cmd/rc/parse.c"
+#line 1646 "sys/cmd/rc/parse.c"
     break;
 
   case 36: /* atom: keyword  */
 #line 98 "sys/cmd/rc/syntax.y"
                       { (yyval.tree) = maketree1(Tword, (yyvsp[0].tree)); }
-#line 1624 "sys/cmd/rc/parse.c"
+#line 1652 "sys/cmd/rc/parse.c"
     break;
 
   case 38: /* word: word '^' atom  */
 #line 102 "sys/cmd/rc/syntax.y"
                       { (yyval.tree) = maketree2('^', (yyvsp[-2].tree), (yyvsp[0].tree)); }
-#line 1630 "sys/cmd/rc/parse.c"
+#line 1658 "sys/cmd/rc/parse.c"
     break;
 
   case 40: /* executable: executable '^' atom  */
 #line 106 "sys/cmd/rc/syntax.y"
                       { (yyval.tree) = maketree2('^', (yyvsp[-2].tree), (yyvsp[0].tree)); }
-#line 1636 "sys/cmd/rc/parse.c"
+#line 1664 "sys/cmd/rc/parse.c"
     break;
 
   case 42: /* nonkeyword: '$' atom  */
 #line 110 "sys/cmd/rc/syntax.y"
-                  { (yyval.tree) = maketree1('$', (yyvsp[0].tree)); }
-#line 1642 "sys/cmd/rc/parse.c"
+                            { (yyval.tree) = maketree1('$', (yyvsp[0].tree)); }
+#line 1670 "sys/cmd/rc/parse.c"
     break;
 
-  case 43: /* nonkeyword: '(' wordsnl ')'  */
+  case 43: /* nonkeyword: '$' atom Tindex words ')'  */
 #line 111 "sys/cmd/rc/syntax.y"
-                  { (yyval.tree) = (yyvsp[-1].tree); }
-#line 1648 "sys/cmd/rc/parse.c"
+                            { (yyval.tree) = maketree2(Tindex, (yyvsp[-3].tree), (yyvsp[-1].tree)); }
+#line 1676 "sys/cmd/rc/parse.c"
     break;
 
-  case 44: /* nonkeyword: Tcount atom  */
+  case 44: /* nonkeyword: '(' wordsnl ')'  */
 #line 112 "sys/cmd/rc/syntax.y"
-                  { (yyval.tree) = maketree1(Tcount, (yyvsp[0].tree)); }
-#line 1654 "sys/cmd/rc/parse.c"
+                            { (yyval.tree) = (yyvsp[-1].tree); }
+#line 1682 "sys/cmd/rc/parse.c"
     break;
 
-  case 45: /* nonkeyword: Tjoin atom  */
+  case 45: /* nonkeyword: Tcount atom  */
 #line 113 "sys/cmd/rc/syntax.y"
-                  { (yyval.tree) = maketree1(Tjoin, (yyvsp[0].tree)); }
-#line 1660 "sys/cmd/rc/parse.c"
+                            { (yyval.tree) = maketree1(Tcount, (yyvsp[0].tree)); }
+#line 1688 "sys/cmd/rc/parse.c"
+    break;
+
+  case 46: /* nonkeyword: Tjoin atom  */
+#line 114 "sys/cmd/rc/syntax.y"
+                            { (yyval.tree) = maketree1(Tjoin, (yyvsp[0].tree)); }
+#line 1694 "sys/cmd/rc/parse.c"
+    break;
+
+  case 47: /* nonkeyword: '`' block  */
+#line 115 "sys/cmd/rc/syntax.y"
+                            { (yyval.tree) = maketree1('`', (yyvsp[0].tree)); }
+#line 1700 "sys/cmd/rc/parse.c"
     break;
 
-  case 55: /* wordsnl: %empty  */
+  case 57: /* words: %empty  */
+#line 123 "sys/cmd/rc/syntax.y"
+             { (yyval.tree) = nil; }
+#line 1706 "sys/cmd/rc/parse.c"
+    break;
+
+  case 58: /* words: words word  */
 #line 124 "sys/cmd/rc/syntax.y"
+             { (yyval.tree) = maketree2(Twords, (yyvsp[-1].tree), (yyvsp[0].tree)); }
+#line 1712 "sys/cmd/rc/parse.c"
+    break;
+
+  case 59: /* wordsnl: %empty  */
+#line 127 "sys/cmd/rc/syntax.y"
                { (yyval.tree) = nil; }
-#line 1666 "sys/cmd/rc/parse.c"
+#line 1718 "sys/cmd/rc/parse.c"
     break;
 
-  case 57: /* wordsnl: wordsnl word  */
-#line 126 "sys/cmd/rc/syntax.y"
+  case 61: /* wordsnl: wordsnl word  */
+#line 129 "sys/cmd/rc/syntax.y"
                {(yyval.tree) = (!(yyvsp[-1].tree)) ? ((!(yyvsp[0].tree)) ? nil : (yyvsp[0].tree)) : ((!(yyvsp[0].tree)) ? (yyvsp[-1].tree) : maketree2(Twords, (yyvsp[-1].tree), (yyvsp[0].tree))); }
-#line 1672 "sys/cmd/rc/parse.c"
+#line 1724 "sys/cmd/rc/parse.c"
     break;
 
 
-#line 1676 "sys/cmd/rc/parse.c"
+#line 1728 "sys/cmd/rc/parse.c"
 
       default: break;
     }
@@ -1896,5 +1948,5 @@ yyreturnlab:
   return yyresult;
 }
 
-#line 131 "sys/cmd/rc/syntax.y"
+#line 134 "sys/cmd/rc/syntax.y"
 
diff --git a/sys/cmd/rc/syntax.y b/sys/cmd/rc/syntax.y
index 2e7e1da..f3c9f29 100644
--- a/sys/cmd/rc/syntax.y
+++ b/sys/cmd/rc/syntax.y
@@ -27,7 +27,7 @@
 %type<tree> line cmds cmdsln body paren block ifbody assign epilog redir;
 %type<tree> cmd basic executable nonkeyword keyword word words wordsnl atom;
 %type<tree> Tfor Tin Twhile Tif Telse Tswitch Ttwiddle Tbang Tsubshell Tfunc;
-%type<tree> Tword Tredir Tpipe;
+%type<tree> Tword Tredir Tpipe Tdup;
 
 /* grammar */
 
@@ -107,11 +107,14 @@ executable:
 
 nonkeyword:
   Tword
-| '$' atom        { $$ = maketree1('$', $2); }
-| '(' wordsnl ')' { $$ = $2; }
-| Tcount atom     { $$ = maketree1(Tcount, $2); }
-| Tjoin atom      { $$ = maketree1(Tjoin, $2); }
-//| '`'  block      { $$ = maketree1('`', $2); }
+| '$' atom                  { $$ = maketree1('$', $2); }
+| '$' atom Tindex words ')' { $$ = maketree2(Tindex, $2, $4); }
+| '(' wordsnl ')'           { $$ = $2; }
+| Tcount atom               { $$ = maketree1(Tcount, $2); }
+| Tjoin atom                { $$ = maketree1(Tjoin, $2); }
+| '`'  block                { $$ = maketree1('`', $2); }
+//| '('  words ')'            { $$ = maketree1(Tparen, $2); }
+//| Tredir block    { $$ = hangchild1($1, $2, 0); $$->type = Tpipefd; }
 
 keyword:
     Tin|Tfor|Twhile|Tif|Telse|Tswitch|Tbang|Tsubshell|Tfunc