feat(rc): cleaner process watching for each job

13 files changed, 725 insertions, 265 deletions

diff --git a/sys/cmd/rc/code.c b/sys/cmd/rc/code.c
index 8dec021..d4dd6e1 100644
--- a/sys/cmd/rc/code.c
+++ b/sys/cmd/rc/code.c
@@ -50,7 +50,7 @@ walk(Tree *node)
 
     switch(node->type){
     default:
-        print(errio, "bad type %d in interpreter walk\n", node->type);
+        print(shell.err, "bad type %d in interpreter walk\n", node->type);
         break;
 
     case '$':
@@ -152,7 +152,7 @@ copycode(Code *c)
 int
 compile(Tree *node)
 {
-    flush(errio);
+    flush(shell.err);
     //print(errio, "%t\n", node);
 
     interpreter.i    = 0;
diff --git a/sys/cmd/rc/exec.c b/sys/cmd/rc/exec.c
index 80cd645..d78cb5d 100644
--- a/sys/cmd/rc/exec.c
+++ b/sys/cmd/rc/exec.c
@@ -31,10 +31,10 @@ static
 void
 pushword(char *str)
 {
-    if(!proc->args)
+    if(!runner->args)
         fatal("attempt to push on empty argument stack\n");
 
-    proc->args->word = makeword(str, proc->args->word);
+    runner->args->word = makeword(str, runner->args->word);
 }
 
 static
@@ -42,14 +42,14 @@ void
 popword(void)
 {
     Word *w;
-    if(!proc->args)
+    if(!runner->args)
         fatal("tried to pop word on empty argument stack\n");
 
-    w = proc->args->word;
+    w = runner->args->word;
     if(!w)
         fatal("tried to pop word but nothing there\n");
 
-    proc->args->word = w->link;
+    runner->args->word = w->link;
     efree(w->str);
     efree(w);
 }
@@ -101,21 +101,21 @@ pushlist(void)
     List *stack = emalloc(sizeof(*stack));
 
     stack->word = nil;
-    stack->link = proc->args;
+    stack->link = runner->args;
 
-    proc->args = stack;
+    runner->args = stack;
 }
 
 static
 void
 poplist(void)
 {
-    List *stack = proc->args;
+    List *stack = runner->args;
     if(!stack)
         fatal("attempted to pop an empty argument stack\n");
 
     freelist(stack->word);
-    proc->args = stack->link;
+    runner->args = stack->link;
     efree(stack);
 }
 
@@ -140,12 +140,12 @@ void
 xx(void)
 {
     popword(); // "exec"
-    if(!proc->args->word){
+    if(!runner->args->word){
         Xerror("empty argument list");
         return;
     }
 
-    execute(proc->args->word, path(proc->args->word->str));
+    execute(runner->args->word, path(runner->args->word->str));
     poplist();
 }
 
@@ -160,15 +160,15 @@ xforkx(void)
     case -1:
         return -1;
     case 0: // child
-        clearwait(proc);
+        clearwait(runner);
 
         if(shell.interactive){
-            proc->pid = getpid();
-            if(proc->pgid <= 0)
-                proc->pgid = proc->pid;
+            runner->pid = getpid();
+            if(runner->pgid <= 0)
+                runner->pgid = runner->pid;
 
-            setpgid(pid, proc->pgid);
-            tcsetpgrp(0, proc->pgid);
+            setpgid(pid, runner->pgid);
+            tcsetpgrp(0, runner->pgid);
 
             signal(SIGINT,  SIG_DFL);
             signal(SIGQUIT, SIG_DFL);
@@ -181,16 +181,16 @@ xforkx(void)
         pushword("exec");
         xx();
 
-        exit(1); // NOTE: xx does not return!
+        exit(2); // NOTE: xx does not return!
         /*unreachable*/
     default: // parent
-        addwait(proc, pid);
+        addwait(runner, pid);
 
         /* ensure the state matches for parent and child */
-        proc->pid = pid;
-        if(proc->pgid <= 0)
-            proc->pgid = pid;
-        setpgid(pid, proc->pgid);
+        runner->pid = pid;
+        if(runner->pgid <= 0)
+            runner->pgid = pid;
+        setpgid(pid, runner->pgid);
 
         return pid;
     }
@@ -205,9 +205,9 @@ pushredir(int type, int from, int to)
     r->type = type;
     r->from = from;
     r->to = to;
-    r->link = proc->redir;
+    r->link = runner->redir;
 
-    proc->redir = r;
+    runner->redir = r;
 }
 
 /* byte code */
@@ -219,17 +219,30 @@ run(Code *c, int pc, Var *local)
 
     new->code.i   = pc;
     new->code.exe = copycode(c);
-    new->args     = nil;
-    new->local    = local;
+
     new->cmd.path = nil;
     new->cmd.io   = nil;
+
+    new->args     = nil;
+    new->local    = local;
+    new->redir    = nil;
+
+    new->flag.i   = 0;
     new->flag.eof = 0;
-    new->line     = 1;
-    new->link     = proc;
 
+    new->wait.status = 0;
+    new->wait.len    = 0;
+    new->wait.cap    = 0;
+    new->wait.on     = nil;
+
+    new->status = 0;
     new->pgid = new->pid = -1;
 
-    proc = new;
+    new->line     = 0;
+    new->link     = runner;
+    new->next     = nil;
+
+    runner = new;
 }
 
 // -----------------------------------------------------------------------
@@ -307,12 +320,12 @@ xdot(void)
     }
 #endif
     /* get input file */
-    if(!proc->args->word){
+    if(!runner->args->word){
         Xerror("usage: . [-i] file [arg ...]\n");
         return;
     }
 
-    base = strdup(proc->args->word->str);
+    base = strdup(runner->args->word->str);
     popword();
     for(fd=-1, p=path(base); p; p = p->link){
         strcpy(file, p->str);
@@ -326,23 +339,23 @@ xdot(void)
     }
 
     if(fd<0){
-        print(errio, "%s: ", base);
+        print(shell.err, "%s: ", base);
         //setstatus("can't open");
         Xerror(".: can't open\n");
         return;
     }
     /* set up for a new command loop */
-    old = proc; // store pointer to old code
+    old = runner; // store pointer to old code
     run(dotcmd, 1, nil);
 
     /* operations on new command stack */
     pushredir(Rclose, fd, 0);
-    proc->cmd.path = base;
-    proc->cmd.io   = openfd(fd);
+    runner->cmd.path = base;
+    runner->cmd.io   = openfd(fd);
 
     /* push $* value */
     pushlist();
-    proc->args->word = old->args->word;
+    runner->args->word = old->args->word;
 
     /* free caller's copy of $* */
     argv = old->args;
@@ -361,7 +374,7 @@ xjob(void)
     int i;
     Thread *job;
 
-    for(i = 0, job = shell.jobs; job; job = job->next)
+    for(i=0, job = shell.jobs; job; job = job->next, i++)
         report(job,i);
 
     poplist();
@@ -376,27 +389,23 @@ xfg(void)
     popword(); // fg
 
     /* get input job id */
-    if(!proc->args->word){
-        print(errio, "usage: fg [pid|\%num]\n");
+    if(!runner->args->word){
+        print(shell.err, "usage: fg [pid|\%num]\n");
         poplist();
         return;
     }
 
-    i = atoi(proc->args->word->str);
+    i = atoi(runner->args->word->str);
     popword(); // [jobid]
 
     for(job=shell.jobs; i > 0; job=job->next, --i)
         ;
-    assert(!job->flag.done);
-
-    addwait(job, job->pid);
-    job->flag.stop = 0;
 
     poplist(); // this goes here?
 
-    job->link = proc, proc = job; // XXX: can this leave orphans?
+    wakeup(job);
+    job->link = runner, runner = job; // XXX: can this leave zombies?
     foreground(job, 1);
-    printf("hi\n");
 }
 
 void
@@ -434,8 +443,8 @@ xboot(int argc, char *argv[])
 
     /* main interpreter loop */
     for(;;){
-        proc->code.i++;
-        (*proc->code.exe[proc->code.i-1].f)();
+        runner->code.i++;
+        (*runner->code.exe[runner->code.i-1].f)();
     }
 }
 
@@ -451,52 +460,55 @@ Xmark(void)
 void
 Xerror(char *msg)
 {
-    print(errio, "rc: %s", msg);
-    flush(errio);
-    while(!proc->flag.i)
+    print(shell.err, "rc: %s", msg);
+    flush(shell.err);
+    while(!runner->flag.i)
         Xreturn();
 }
 
 void
 Xreturn(void)
 {
-    Thread *run = proc;
+    Thread *run = runner;
 
+    switch(run->wait.status){
     /*
      * If our job is still running we must:
      * 1. move program one step back to rerun Xreturn upon recall
      * 2. return to our calling thread
      * 3. don't free!
      */
-    if(run->flag.stop){
+    case PStop:
         run->code.i--;
-        proc = run->link;
+        runner = run->link;
         return;
-    }
-
     /*
      * If our job has finished:
      * 1. remove from our list
-     * 2. clean up its memory!
+     * 2. continue to clean up its memory
      */
-    if(run->flag.done)
+    case PDone:
         deljob(run);
+        /* fallthrough */
+    default:
+        ;
+    }
 
     while(run->args)
         poplist();
     freecode(run->code.exe);
-    efree(run->wait.pid);
+    efree(run->wait.on);
 
-    proc = run->link;
+    runner = run->link;
     efree(run);
-    if(!proc)
+    if(!runner)
         exit(0);
 }
 
 void
 Xword(void)
 {
-    pushword(proc->code.exe[proc->code.i++].s);
+    pushword(runner->code.exe[runner->code.i++].s);
 }
 
 void
@@ -506,18 +518,18 @@ Xdollar(void)
     char *s, *t;
     Word *a, *star;
 
-    if(count(proc->args->word)!=1){
+    if(count(runner->args->word)!=1){
         Xerror("variable name not singleton!\n");
         return;
     }
-    s = proc->args->word->str;
+    s = runner->args->word->str;
     // deglob(s);
     n = 0;
 
     for(t = s;'0'<=*t && *t<='9';t++) 
         n = n*10+*t-'0';
 
-    a = proc->args->link->word;
+    a = runner->args->link->word;
 
     if(n==0 || *t)
         a = copywords(var(s)->val, a);
@@ -532,7 +544,7 @@ Xdollar(void)
     }
 
     poplist();
-    proc->args->word = a;
+    runner->args->word = a;
 }
 
 void
@@ -540,22 +552,22 @@ Xassign(void)
 {
     Var *v;
 
-    if(count(proc->args->word)!=1){
+    if(count(runner->args->word)!=1){
         Xerror("variable name not singleton!\n");
         return;
     }
     //deglob(runq->argv->words->word);
-    v = var(proc->args->word->str);
+    v = var(runner->args->word->str);
     poplist();
 
     //globlist();
     freewords(v->val);
-    v->val = proc->args->word;
+    v->val = runner->args->word;
     v->new = 1;
     if(v->update)
         v->update(v);
 
-    proc->args->word = nil;
+    runner->args->word = nil;
     poplist();
 }
 
@@ -566,8 +578,8 @@ Xreadcmd(void)
     Thread *root;
     Word *prompt;
 
-    flush(errio);
-    root = proc;
+    flush(shell.err);
+    root = runner;
 
     if(yyparse()){
         exit(1);
@@ -576,22 +588,22 @@ Xreadcmd(void)
         run(compiled, 1, root->local);
     }
 
-    // killzombies();
+    killzombies();
     freeparsetree();
 }
 
 void
 Xlocal(void)
 {
-    if(count(proc->args->word)!=1){
+    if(count(runner->args->word)!=1){
         Xerror("variable name must be singleton\n");
         return;
     }
     //deglob(shell->args->word->str);
 
-    proc->local      = makevar(strdup(proc->args->word->str), proc->local);
-    proc->local->val = copywords(proc->args->link->word, nil);
-    proc->local->new = 1;
+    runner->local      = makevar(strdup(runner->args->word->str), runner->local);
+    runner->local->val = copywords(runner->args->link->word, nil);
+    runner->local->new = 1;
 
     poplist();
     poplist();
@@ -600,13 +612,11 @@ Xlocal(void)
 void
 Xunlocal(void)
 {
-    Var *v = proc->local, *hide;
+    Var *v = runner->local, *hide;
     if(!v)
         fatal("Xunlocal: no locals!\n", 0);
 
-    printf("unlocal\n");
-
-    proc->local = v->link;
+    runner->local = v->link;
     hide = var(v->name);
     hide->new = 1;
 
@@ -623,19 +633,18 @@ Xbasic(void)
     int pid, status;
     struct Builtin *b;
 
-    arg = proc->args->word;
+    arg = runner->args->word;
     if(!arg){
         Xerror("empty argument list\n");
         return;
     }
-    /* print(errio, "recieved arg: %v\n", arg); // for debugging */
-    flush(errio);
+    flush(shell.err);
 
     v = var(arg->str);
     if(v->func){
-        // xfunc(v);
         return;
     }
+
     // see if it matches a builtin
     for(b = builtin; b->name; b++){
         if(strcmp(b->name, arg->str)==0){
@@ -645,8 +654,7 @@ Xbasic(void)
     }
 
     /* if we are here then it's an external command */
-    killzombies();
-    addjob(proc);
+    addjob(runner);
 
     // run the external command
     if((pid = xforkx()) < 0) {
@@ -657,9 +665,9 @@ Xbasic(void)
     poplist();
 
     if(!shell.interactive)
-        waitall(proc);
+        waitall(runner);
 
-    foreground(proc, 0); // waits for child
+    foreground(runner, 0); // waits for child
 }
 
 void
diff --git a/sys/cmd/rc/input.c b/sys/cmd/rc/input.c
index 4c6b37f..228b2d8 100644
--- a/sys/cmd/rc/input.c
+++ b/sys/cmd/rc/input.c
@@ -995,7 +995,7 @@ notty(void)
 

     for(;;){

         c = fgetc(stdin);

-        put(&proc->cmd.io, c);

+        put(&runner->cmd.io, c);

     }

 }

 

@@ -1019,17 +1019,17 @@ readline(char *prompt)
     int n;

 

     // reset the command buffer

-    proc->cmd.io->e = proc->cmd.io->b = proc->cmd.io->buf;

+    runner->cmd.io->e = runner->cmd.io->b = runner->cmd.io->buf;

 

     if(!shell.interactive)

         return notty();

 

-    if((n = raw(proc->cmd.io->e, proc->cmd.io->cap-1, prompt)) == -1)

+    if((n = raw(runner->cmd.io->e, runner->cmd.io->cap-1, prompt)) == -1)

         return 0;

-    proc->cmd.io->e += n;

+    runner->cmd.io->e += n;

 

     /* insert a newline character at the end */

-    put(&proc->cmd.io, '\n');

+    put(&runner->cmd.io, '\n');

     printf("\n");

 

     return 1;

diff --git a/sys/cmd/rc/job.c b/sys/cmd/rc/job.c
new file mode 100644
index 0000000..779ce6c
--- /dev/null
+++ b/sys/cmd/rc/job.c
@@ -0,0 +1,82 @@
+#include "rc.h"
+
+#include <signal.h>
+#include <termios.h>
+
+// -----------------------------------------------------------------------
+// exports
+
+Thread *
+getjob(int pid, int *index)
+{
+    int i;
+    Thread *job;
+    for(i=0,job=shell.jobs; job && job->pid != pid; i++, job=job->next)
+        ;
+
+    return job;
+}
+
+void
+report(Thread *job, int index)
+{
+    switch(job->wait.status){
+        case PDone:
+            print(shell.err, "job %d [%d]: done\n",      index, job->pid);
+            break;
+        case PStop:
+            print(shell.err, "job %d [%d]: suspended\n", index, job->pid);
+            break;
+        case PAgain:
+            print(shell.err, "job %d [%d]: continued\n", index, job->pid);
+            break;
+        case PRun:
+            print(shell.err, "job %d [%d]: running\n",   index, job->pid);
+            break;
+        default:
+            fatal("bad wait status: %d\n", job->wait.status);
+    }
+}
+
+void
+wakeup(Thread *t)
+{
+    int i;
+    t->wait.status = PRun;
+    for(i=0; i < t->wait.len; i++){
+        if(t->wait.on[i].status == PStop)
+            t->wait.on[i].status = PRun;
+    }
+}
+
+void
+foreground(Thread *job, int signal)
+{
+    tcsetpgrp(0, job->pgid);
+    if(signal){
+        if(kill(-job->pgid, SIGCONT) < 0)
+            perror("kill[SIGCONT]");
+    }
+
+    waitall(job);
+
+    tcsetpgrp(0, shell.pid);
+}
+
+void
+addjob(Thread *job)
+{
+    job->next = shell.jobs;
+    shell.jobs = job;
+}
+
+void
+deljob(Thread *job)
+{
+    Thread **jp;
+
+    for(jp = &shell.jobs; *jp && *jp != job; jp = &(*jp)->next)
+        ;
+
+    *jp = job->next;
+}
diff --git a/sys/cmd/rc/lex.c b/sys/cmd/rc/lex.c
index e7c7d7d..b4a2e8c 100644
--- a/sys/cmd/rc/lex.c
+++ b/sys/cmd/rc/lex.c
@@ -15,16 +15,17 @@ struct Lexer
 static struct Lexer lexer = { .c={0, EOF}, .doprompt=1 };
 
 void
-yyerror(char *msg)
+yyerror(const char *msg)
 {
-    print(errio, "\nrc: ");
+    print(shell.err, "\nrc:%d: ", runner->line);
 
     if(lexer.buf[0] && lexer.buf[0]!='\n')
-        print(errio, "@ %q: ", lexer.buf);
+        print(shell.err, "%q: ", lexer.buf);
 
-    print(errio, "%s\n", msg);
-    flush(errio);
+    print(shell.err, "%s\n", msg);
+    flush(shell.err);
 
+    /* consume remaining tokens */
     while(lexer.c[0] !='\n' && lexer.c[0] != EOF)
         advance();
 }
@@ -40,18 +41,18 @@ readc(void)
         peek = EOF;
         return c;
     }
-    if(proc->flag.eof)
+    if(runner->flag.eof)
         return EOF;
 
     if(!prompt(&lexer.doprompt))
         exit(1); // XXX: hack for signal handling right now...
 
-    c = get(proc->cmd.io);
+    c = get(runner->cmd.io);
 
     lexer.doprompt = lexer.doprompt || c=='\n' || c==EOF;
 
     if(c==EOF)
-        proc->flag.eof = 1;
+        runner->flag.eof = 1;
 
     return c;
 }
diff --git a/sys/cmd/rc/main.c b/sys/cmd/rc/main.c
index d1bbd06..557030a 100644
--- a/sys/cmd/rc/main.c
+++ b/sys/cmd/rc/main.c
@@ -8,9 +8,8 @@
 // -----------------------------------------------------------------------
 // globals
 
-Io     *errio = nil;
-Thread *proc  = nil;
-Shell shell   = { 0 };
+Thread *runner = nil;
+Shell shell    = { 0 };
 
 // -----------------------------------------------------------------------
 // functions
@@ -57,7 +56,7 @@ main(int argc, char *argv[])
     Code bootstrap[32];
     char num[12];
 
-    errio = openfd(2);
+    shell.err = openfd(2);
 
     initenv();
     initpath();
diff --git a/sys/cmd/rc/parse.c b/sys/cmd/rc/parse.c
index e2e4afa..42834ed 100644
--- a/sys/cmd/rc/parse.c
+++ b/sys/cmd/rc/parse.c
@@ -67,12 +67,12 @@
 
 
 /* First part of user prologue.  */
-#line 5 "sys/cmd/rc/syntax.y"
+#line 7 "sys/cmd/rc/syntax.y"
 
     #include "rc.h"
 
     int  yylex(void);
-    void yyerror(char *);
+    void yyerror(const char *);
 
 #line 78 "sys/cmd/rc/parse.c"
 
@@ -133,14 +133,15 @@ enum yysymbol_kind_t
   YYSYMBOL_cmds = 28,                      /* cmds  */
   YYSYMBOL_cmdsln = 29,                    /* cmdsln  */
   YYSYMBOL_ifbody = 30,                    /* ifbody  */
-  YYSYMBOL_cmd = 31,                       /* cmd  */
-  YYSYMBOL_basic = 32,                     /* basic  */
-  YYSYMBOL_atom = 33,                      /* atom  */
-  YYSYMBOL_word = 34,                      /* word  */
-  YYSYMBOL_executable = 35,                /* executable  */
-  YYSYMBOL_nonkeyword = 36,                /* nonkeyword  */
-  YYSYMBOL_keyword = 37,                   /* keyword  */
-  YYSYMBOL_nl = 38                         /* nl  */
+  YYSYMBOL_assign = 31,                    /* assign  */
+  YYSYMBOL_cmd = 32,                       /* cmd  */
+  YYSYMBOL_basic = 33,                     /* basic  */
+  YYSYMBOL_atom = 34,                      /* atom  */
+  YYSYMBOL_word = 35,                      /* word  */
+  YYSYMBOL_executable = 36,                /* executable  */
+  YYSYMBOL_nonkeyword = 37,                /* nonkeyword  */
+  YYSYMBOL_keyword = 38,                   /* keyword  */
+  YYSYMBOL_nl = 39                         /* nl  */
 };
 typedef enum yysymbol_kind_t yysymbol_kind_t;
 
@@ -338,7 +339,7 @@ typedef int yy_state_fast_t;
 
 #define YY_ASSERT(E) ((void) (0 && (E)))
 
-#if !defined yyoverflow
+#if 1
 
 /* The parser invokes alloca or malloc; define the necessary symbols.  */
 
@@ -403,7 +404,7 @@ void free (void *); /* INFRINGES ON USER NAME SPACE */
 #   endif
 #  endif
 # endif
-#endif /* !defined yyoverflow */
+#endif /* 1 */
 
 #if (! defined yyoverflow \
      && (! defined __cplusplus \
@@ -466,18 +467,18 @@ union yyalloc
 #endif /* !YYCOPY_NEEDED */
 
 /* YYFINAL -- State number of the termination state.  */
-#define YYFINAL  24
+#define YYFINAL  25
 /* YYLAST -- Last index in YYTABLE.  */
-#define YYLAST   49
+#define YYLAST   53
 
 /* YYNTOKENS -- Number of terminals.  */
 #define YYNTOKENS  22
 /* YYNNTS -- Number of nonterminals.  */
-#define YYNNTS  17
+#define YYNNTS  18
 /* YYNRULES -- Number of rules.  */
-#define YYNRULES  33
+#define YYNRULES  35
 /* YYNSTATES -- Number of states.  */
-#define YYNSTATES  48
+#define YYNSTATES  52
 
 /* YYMAXUTOK -- Last valid token kind.  */
 #define YYMAXUTOK   266
@@ -527,17 +528,17 @@ static const yytype_int8 yytranslate[] =
 /* YYRLINE[YYN] -- Source line where rule number YYN was defined.  */
 static const yytype_int8 yyrline[] =
 {
-       0,    34,    34,    35,    38,    39,    42,    43,    46,    49,
-      52,    53,    56,    57,    60,    61,    67,    68,    69,    70,
-      73,    74,    83,    84,    87,    88,    91,    92,    95,    96,
-      99,    99,   101,   103
+       0,    36,    36,    37,    40,    41,    44,    45,    48,    51,
+      54,    55,    58,    59,    62,    63,    66,    69,    70,    71,
+      72,    73,    76,    77,    86,    87,    90,    91,    94,    95,
+      98,    99,   102,   102,   104,   106
 };
 #endif
 
 /** Accessing symbol of state STATE.  */
 #define YY_ACCESSING_SYMBOL(State) YY_CAST (yysymbol_kind_t, yystos[State])
 
-#if YYDEBUG || 0
+#if 1
 /* The user-facing name of the symbol whose (internal) number is
    YYSYMBOL.  No bounds checking.  */
 static const char *yysymbol_name (yysymbol_kind_t yysymbol) YY_ATTRIBUTE_UNUSED;
@@ -550,8 +551,8 @@ static const char *const yytname[] =
   "Telse", "Tbang", "Targs", "Tbasic", "Tparen", "Tblock", "Twhile",
   "'\\n'", "'$'", "'('", "')'", "'{'", "'}'", "';'", "'&'", "'='", "'^'",
   "$accept", "rc", "line", "body", "paren", "block", "cmds", "cmdsln",
-  "ifbody", "cmd", "basic", "atom", "word", "executable", "nonkeyword",
-  "keyword", "nl", YY_NULLPTR
+  "ifbody", "assign", "cmd", "basic", "atom", "word", "executable",
+  "nonkeyword", "keyword", "nl", YY_NULLPTR
 };
 
 static const char *
@@ -561,7 +562,7 @@ yysymbol_name (yysymbol_kind_t yysymbol)
 }
 #endif
 
-#define YYPACT_NINF (-10)
+#define YYPACT_NINF (-14)
 
 #define yypact_value_is_default(Yyn) \
   ((Yyn) == YYPACT_NINF)
@@ -575,11 +576,12 @@ yysymbol_name (yysymbol_kind_t yysymbol)
    STATE-NUM.  */
 static const yytype_int8 yypact[] =
 {
-       3,   -10,    -2,    21,     7,    15,     9,   -10,     7,    22,
-      21,    10,   -10,     7,   -10,   -10,   -10,   -10,   -10,   -10,
-      18,   -10,     7,    20,   -10,   -10,   -10,   -10,   -10,   -10,
-      23,    21,    27,     1,   -10,   -10,   -10,    21,   -10,   -10,
-     -10,    38,   -10,   -10,   -10,   -10,     1,   -10
+       3,   -14,   -13,    24,    10,     5,    19,   -14,    10,    10,
+      28,    24,    -3,   -14,    10,   -14,   -14,   -14,   -14,   -14,
+     -14,    -2,   -14,    10,    26,   -14,   -14,   -14,   -14,   -14,
+     -14,   -14,    21,    24,    24,    25,     8,   -14,   -14,   -14,
+      24,    21,   -14,   -14,   -14,    38,   -14,   -14,   -14,   -14,
+       8,   -14
 };
 
 /* YYDEFACT[STATE-NUM] -- Default reduction number in state STATE-NUM.
@@ -587,25 +589,26 @@ static const yytype_int8 yypact[] =
    means the default is an error.  */
 static const yytype_int8 yydefact[] =
 {
-      16,    28,     0,     0,    16,     0,     0,    18,    16,     4,
-      17,    20,    26,    16,    32,    30,    31,    29,    22,    23,
-       0,    12,    16,     6,     1,     3,     5,    10,    11,    24,
-      21,     0,     0,    16,     9,     7,    13,     0,    27,     8,
-      33,    18,    19,    14,    25,    32,    16,    15
+      17,    30,     0,     0,    17,     0,     0,    19,    17,    17,
+       4,    18,    22,    28,    17,    34,    32,    33,    31,    24,
+      25,     0,    12,    17,     6,     1,     3,     5,    20,    10,
+      11,    26,    23,     0,     0,     0,    17,     9,     7,    13,
+       0,    16,    29,     8,    35,    19,    21,    14,    27,    34,
+      17,    15
 };
 
 /* YYPGOTO[NTERM-NUM].  */
 static const yytype_int8 yypgoto[] =
 {
-     -10,   -10,    37,     5,   -10,    14,    29,   -10,   -10,     0,
-     -10,    -9,   -10,   -10,    -1,   -10,     4
+     -14,   -14,    40,    11,   -14,    13,    22,   -14,   -14,   -14,
+       0,   -14,     1,    18,   -14,    -1,   -14,     4
 };
 
 /* YYDEFGOTO[NTERM-NUM].  */
 static const yytype_int8 yydefgoto[] =
 {
-       0,     5,     6,    20,    14,     7,    21,    22,    42,    23,
-      10,    17,    30,    11,    12,    19,    33
+       0,     5,     6,    21,    15,     7,    22,    23,    46,     9,
+      24,    11,    31,    32,    12,    13,    20,    36
 };
 
 /* YYTABLE[YYPACT[STATE-NUM]] -- What to do in state STATE-NUM.  If
@@ -613,20 +616,22 @@ static const yytype_int8 yydefgoto[] =
    number is the opposite.  If YYTABLE_NINF, syntax error.  */
 static const yytype_int8 yytable[] =
 {
-       9,    29,    18,    -2,     1,     2,     1,     2,     9,    18,
-       1,     2,    13,    40,     3,    24,     3,     4,    32,     4,
-       3,    25,    38,     4,     1,    15,    16,    35,    44,     8,
-      18,    31,    36,    43,     3,    34,    18,     8,    27,    28,
-      27,    28,    39,    45,    37,    26,    47,    41,     0,    46
+      10,    14,    19,    -2,    18,    25,     1,     2,    10,    28,
+      19,     1,     2,     1,     2,    37,     3,    33,    34,     4,
+      44,     3,     8,     3,     4,    35,     4,     1,    16,    17,
+       8,    26,    19,    19,    38,    42,    47,     3,    39,    19,
+      43,    48,    40,    49,    29,    30,    29,    30,    27,    45,
+      51,    41,     0,    50
 };
 
 static const yytype_int8 yycheck[] =
 {
-       0,    10,     3,     0,     3,     4,     3,     4,     8,    10,
-       3,     4,    14,    12,    13,     0,    13,    16,    13,    16,
-      13,    12,    31,    16,     3,     4,     5,    22,    37,     0,
-      31,    21,    12,    33,    13,    17,    37,     8,    18,    19,
-      18,    19,    15,     5,    21,     8,    46,    33,    -1,    45
+       0,    14,     3,     0,     3,     0,     3,     4,     8,     9,
+      11,     3,     4,     3,     4,    17,    13,    20,    21,    16,
+      12,    13,     0,    13,    16,    14,    16,     3,     4,     5,
+       8,    12,    33,    34,    23,    34,    36,    13,    12,    40,
+      15,    40,    21,     5,    18,    19,    18,    19,     8,    36,
+      50,    33,    -1,    49
 };
 
 /* YYSTOS[STATE-NUM] -- The symbol kind of the accessing symbol of
@@ -634,28 +639,29 @@ static const yytype_int8 yycheck[] =
 static const yytype_int8 yystos[] =
 {
        0,     3,     4,    13,    16,    23,    24,    27,    28,    31,
-      32,    35,    36,    14,    26,     4,     5,    33,    36,    37,
-      25,    28,    29,    31,     0,    12,    24,    18,    19,    33,
-      34,    21,    25,    38,    17,    25,    12,    21,    33,    15,
-      12,    27,    30,    31,    33,     5,    38,    31
+      32,    33,    36,    37,    14,    26,     4,     5,    34,    37,
+      38,    25,    28,    29,    32,     0,    12,    24,    32,    18,
+      19,    34,    35,    20,    21,    25,    39,    17,    25,    12,
+      21,    35,    34,    15,    12,    27,    30,    32,    34,     5,
+      39,    32
 };
 
 /* YYR1[RULE-NUM] -- Symbol kind of the left-hand side of rule RULE-NUM.  */
 static const yytype_int8 yyr1[] =
 {
        0,    22,    23,    23,    24,    24,    25,    25,    26,    27,
-      28,    28,    29,    29,    30,    30,    31,    31,    31,    31,
+      28,    28,    29,    29,    30,    30,    31,    32,    32,    32,
       32,    32,    33,    33,    34,    34,    35,    35,    36,    36,
-      37,    37,    38,    38
+      37,    37,    38,    38,    39,    39
 };
 
 /* YYR2[RULE-NUM] -- Number of symbols on the right-hand side of rule RULE-NUM.  */
 static const yytype_int8 yyr2[] =
 {
        0,     2,     0,     2,     1,     2,     1,     2,     3,     3,
-       2,     2,     1,     2,     1,     4,     0,     1,     1,     4,
-       1,     2,     1,     1,     1,     3,     1,     3,     1,     2,
-       1,     1,     0,     2
+       2,     2,     1,     2,     1,     4,     3,     0,     1,     1,
+       2,     4,     1,     2,     1,     1,     1,     3,     1,     3,
+       1,     2,     1,     1,     0,     2
 };
 
 
@@ -838,8 +844,275 @@ int yydebug;
 #endif
 
 
+/* Context of a parse error.  */
+typedef struct
+{
+  yy_state_t *yyssp;
+  yysymbol_kind_t yytoken;
+} yypcontext_t;
+
+/* Put in YYARG at most YYARGN of the expected tokens given the
+   current YYCTX, and return the number of tokens stored in YYARG.  If
+   YYARG is null, return the number of expected tokens (guaranteed to
+   be less than YYNTOKENS).  Return YYENOMEM on memory exhaustion.
+   Return 0 if there are more than YYARGN expected tokens, yet fill
+   YYARG up to YYARGN. */
+static int
+yypcontext_expected_tokens (const yypcontext_t *yyctx,
+                            yysymbol_kind_t yyarg[], int yyargn)
+{
+  /* Actual size of YYARG. */
+  int yycount = 0;
+  int yyn = yypact[+*yyctx->yyssp];
+  if (!yypact_value_is_default (yyn))
+    {
+      /* Start YYX at -YYN if negative to avoid negative indexes in
+         YYCHECK.  In other words, skip the first -YYN actions for
+         this state because they are default actions.  */
+      int yyxbegin = yyn < 0 ? -yyn : 0;
+      /* Stay within bounds of both yycheck and yytname.  */
+      int yychecklim = YYLAST - yyn + 1;
+      int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
+      int yyx;
+      for (yyx = yyxbegin; yyx < yyxend; ++yyx)
+        if (yycheck[yyx + yyn] == yyx && yyx != YYSYMBOL_YYerror
+            && !yytable_value_is_error (yytable[yyx + yyn]))
+          {
+            if (!yyarg)
+              ++yycount;
+            else if (yycount == yyargn)
+              return 0;
+            else
+              yyarg[yycount++] = YY_CAST (yysymbol_kind_t, yyx);
+          }
+    }
+  if (yyarg && yycount == 0 && 0 < yyargn)
+    yyarg[0] = YYSYMBOL_YYEMPTY;
+  return yycount;
+}
+
+
+
+
+#ifndef yystrlen
+# if defined __GLIBC__ && defined _STRING_H
+#  define yystrlen(S) (YY_CAST (YYPTRDIFF_T, strlen (S)))
+# else
+/* Return the length of YYSTR.  */
+static YYPTRDIFF_T
+yystrlen (const char *yystr)
+{
+  YYPTRDIFF_T yylen;
+  for (yylen = 0; yystr[yylen]; yylen++)
+    continue;
+  return yylen;
+}
+# endif
+#endif
+
+#ifndef yystpcpy
+# if defined __GLIBC__ && defined _STRING_H && defined _GNU_SOURCE
+#  define yystpcpy stpcpy
+# else
+/* Copy YYSRC to YYDEST, returning the address of the terminating '\0' in
+   YYDEST.  */
+static char *
+yystpcpy (char *yydest, const char *yysrc)
+{
+  char *yyd = yydest;
+  const char *yys = yysrc;
 
+  while ((*yyd++ = *yys++) != '\0')
+    continue;
 
+  return yyd - 1;
+}
+# endif
+#endif
+
+#ifndef yytnamerr
+/* Copy to YYRES the contents of YYSTR after stripping away unnecessary
+   quotes and backslashes, so that it's suitable for yyerror.  The
+   heuristic is that double-quoting is unnecessary unless the string
+   contains an apostrophe, a comma, or backslash (other than
+   backslash-backslash).  YYSTR is taken from yytname.  If YYRES is
+   null, do not copy; instead, return the length of what the result
+   would have been.  */
+static YYPTRDIFF_T
+yytnamerr (char *yyres, const char *yystr)
+{
+  if (*yystr == '"')
+    {
+      YYPTRDIFF_T yyn = 0;
+      char const *yyp = yystr;
+      for (;;)
+        switch (*++yyp)
+          {
+          case '\'':
+          case ',':
+            goto do_not_strip_quotes;
+
+          case '\\':
+            if (*++yyp != '\\')
+              goto do_not_strip_quotes;
+            else
+              goto append;
+
+          append:
+          default:
+            if (yyres)
+              yyres[yyn] = *yyp;
+            yyn++;
+            break;
+
+          case '"':
+            if (yyres)
+              yyres[yyn] = '\0';
+            return yyn;
+          }
+    do_not_strip_quotes: ;
+    }
+
+  if (yyres)
+    return yystpcpy (yyres, yystr) - yyres;
+  else
+    return yystrlen (yystr);
+}
+#endif
+
+
+static int
+yy_syntax_error_arguments (const yypcontext_t *yyctx,
+                           yysymbol_kind_t yyarg[], int yyargn)
+{
+  /* Actual size of YYARG. */
+  int yycount = 0;
+  /* There are many possibilities here to consider:
+     - If this state is a consistent state with a default action, then
+       the only way this function was invoked is if the default action
+       is an error action.  In that case, don't check for expected
+       tokens because there are none.
+     - The only way there can be no lookahead present (in yychar) is if
+       this state is a consistent state with a default action.  Thus,
+       detecting the absence of a lookahead is sufficient to determine
+       that there is no unexpected or expected token to report.  In that
+       case, just report a simple "syntax error".
+     - Don't assume there isn't a lookahead just because this state is a
+       consistent state with a default action.  There might have been a
+       previous inconsistent state, consistent state with a non-default
+       action, or user semantic action that manipulated yychar.
+     - Of course, the expected token list depends on states to have
+       correct lookahead information, and it depends on the parser not
+       to perform extra reductions after fetching a lookahead from the
+       scanner and before detecting a syntax error.  Thus, state merging
+       (from LALR or IELR) and default reductions corrupt the expected
+       token list.  However, the list is correct for canonical LR with
+       one exception: it will still contain any token that will not be
+       accepted due to an error action in a later state.
+  */
+  if (yyctx->yytoken != YYSYMBOL_YYEMPTY)
+    {
+      int yyn;
+      if (yyarg)
+        yyarg[yycount] = yyctx->yytoken;
+      ++yycount;
+      yyn = yypcontext_expected_tokens (yyctx,
+                                        yyarg ? yyarg + 1 : yyarg, yyargn - 1);
+      if (yyn == YYENOMEM)
+        return YYENOMEM;
+      else
+        yycount += yyn;
+    }
+  return yycount;
+}
+
+/* Copy into *YYMSG, which is of size *YYMSG_ALLOC, an error message
+   about the unexpected token YYTOKEN for the state stack whose top is
+   YYSSP.
+
+   Return 0 if *YYMSG was successfully written.  Return -1 if *YYMSG is
+   not large enough to hold the message.  In that case, also set
+   *YYMSG_ALLOC to the required number of bytes.  Return YYENOMEM if the
+   required number of bytes is too large to store.  */
+static int
+yysyntax_error (YYPTRDIFF_T *yymsg_alloc, char **yymsg,
+                const yypcontext_t *yyctx)
+{
+  enum { YYARGS_MAX = 5 };
+  /* Internationalized format string. */
+  const char *yyformat = YY_NULLPTR;
+  /* Arguments of yyformat: reported tokens (one for the "unexpected",
+     one per "expected"). */
+  yysymbol_kind_t yyarg[YYARGS_MAX];
+  /* Cumulated lengths of YYARG.  */
+  YYPTRDIFF_T yysize = 0;
+
+  /* Actual size of YYARG. */
+  int yycount = yy_syntax_error_arguments (yyctx, yyarg, YYARGS_MAX);
+  if (yycount == YYENOMEM)
+    return YYENOMEM;
+
+  switch (yycount)
+    {
+#define YYCASE_(N, S)                       \
+      case N:                               \
+        yyformat = S;                       \
+        break
+    default: /* Avoid compiler warnings. */
+      YYCASE_(0, YY_("syntax error"));
+      YYCASE_(1, YY_("syntax error, unexpected %s"));
+      YYCASE_(2, YY_("syntax error, unexpected %s, expecting %s"));
+      YYCASE_(3, YY_("syntax error, unexpected %s, expecting %s or %s"));
+      YYCASE_(4, YY_("syntax error, unexpected %s, expecting %s or %s or %s"));
+      YYCASE_(5, YY_("syntax error, unexpected %s, expecting %s or %s or %s or %s"));
+#undef YYCASE_
+    }
+
+  /* Compute error message size.  Don't count the "%s"s, but reserve
+     room for the terminator.  */
+  yysize = yystrlen (yyformat) - 2 * yycount + 1;
+  {
+    int yyi;
+    for (yyi = 0; yyi < yycount; ++yyi)
+      {
+        YYPTRDIFF_T yysize1
+          = yysize + yytnamerr (YY_NULLPTR, yytname[yyarg[yyi]]);
+        if (yysize <= yysize1 && yysize1 <= YYSTACK_ALLOC_MAXIMUM)
+          yysize = yysize1;
+        else
+          return YYENOMEM;
+      }
+  }
+
+  if (*yymsg_alloc < yysize)
+    {
+      *yymsg_alloc = 2 * yysize;
+      if (! (yysize <= *yymsg_alloc
+             && *yymsg_alloc <= YYSTACK_ALLOC_MAXIMUM))
+        *yymsg_alloc = YYSTACK_ALLOC_MAXIMUM;
+      return -1;
+    }
+
+  /* Avoid sprintf, as that infringes on the user's name space.
+     Don't have undefined behavior even if the translation
+     produced a string with the wrong number of "%s"s.  */
+  {
+    char *yyp = *yymsg;
+    int yyi = 0;
+    while ((*yyp = *yyformat) != '\0')
+      if (*yyp == '%' && yyformat[1] == 's' && yyi < yycount)
+        {
+          yyp += yytnamerr (yyp, yytname[yyarg[yyi++]]);
+          yyformat += 2;
+        }
+      else
+        {
+          ++yyp;
+          ++yyformat;
+        }
+  }
+  return 0;
+}
 
 
 /*-----------------------------------------------.
@@ -908,7 +1181,10 @@ yyparse (void)
      action routines.  */
   YYSTYPE yyval;
 
-
+  /* Buffer for error messages, and its allocated size.  */
+  char yymsgbuf[128];
+  char *yymsg = yymsgbuf;
+  YYPTRDIFF_T yymsg_alloc = sizeof yymsgbuf;
 
 #define YYPOPSTACK(N)   (yyvsp -= (N), yyssp -= (N))
 
@@ -1119,109 +1395,121 @@ yyreduce:
   switch (yyn)
     {
   case 2: /* rc: %empty  */
-#line 34 "sys/cmd/rc/syntax.y"
+#line 36 "sys/cmd/rc/syntax.y"
             { return 0; }
-#line 1125 "sys/cmd/rc/parse.c"
+#line 1401 "sys/cmd/rc/parse.c"
     break;
 
   case 3: /* rc: line '\n'  */
-#line 35 "sys/cmd/rc/syntax.y"
+#line 37 "sys/cmd/rc/syntax.y"
             { return compile((yyvsp[-1].tree)); }
-#line 1131 "sys/cmd/rc/parse.c"
+#line 1407 "sys/cmd/rc/parse.c"
     break;
 
   case 5: /* line: cmds line  */
-#line 39 "sys/cmd/rc/syntax.y"
+#line 41 "sys/cmd/rc/syntax.y"
             { (yyval.tree) = maketree2(';', (yyvsp[-1].tree), (yyvsp[0].tree)); }
-#line 1137 "sys/cmd/rc/parse.c"
+#line 1413 "sys/cmd/rc/parse.c"
     break;
 
   case 7: /* body: cmdsln body  */
-#line 43 "sys/cmd/rc/syntax.y"
+#line 45 "sys/cmd/rc/syntax.y"
               { (yyval.tree) = maketree2(';', (yyvsp[-1].tree), (yyvsp[0].tree)); }
-#line 1143 "sys/cmd/rc/parse.c"
+#line 1419 "sys/cmd/rc/parse.c"
     break;
 
   case 8: /* paren: '(' body ')'  */
-#line 46 "sys/cmd/rc/syntax.y"
+#line 48 "sys/cmd/rc/syntax.y"
                { (yyval.tree) = maketree1(Tparen, (yyvsp[-1].tree)); }
-#line 1149 "sys/cmd/rc/parse.c"
+#line 1425 "sys/cmd/rc/parse.c"
     break;
 
   case 9: /* block: '{' body '}'  */
-#line 49 "sys/cmd/rc/syntax.y"
+#line 51 "sys/cmd/rc/syntax.y"
                { (yyval.tree) = maketree1(Tblock, (yyvsp[-1].tree)); }
-#line 1155 "sys/cmd/rc/parse.c"
+#line 1431 "sys/cmd/rc/parse.c"
     break;
 
   case 11: /* cmds: cmd '&'  */
-#line 53 "sys/cmd/rc/syntax.y"
+#line 55 "sys/cmd/rc/syntax.y"
           { (yyval.tree) = maketree1('&', (yyvsp[-1].tree)); }
-#line 1161 "sys/cmd/rc/parse.c"
+#line 1437 "sys/cmd/rc/parse.c"
     break;
 
   case 14: /* ifbody: cmd  */
-#line 60 "sys/cmd/rc/syntax.y"
+#line 62 "sys/cmd/rc/syntax.y"
                      { (yyval.tree) = maketree2(Tif, nil, (yyvsp[0].tree)); }
-#line 1167 "sys/cmd/rc/parse.c"
+#line 1443 "sys/cmd/rc/parse.c"
     break;
 
   case 15: /* ifbody: block Telse nl cmd  */
-#line 61 "sys/cmd/rc/syntax.y"
+#line 63 "sys/cmd/rc/syntax.y"
                      { (yyval.tree) = maketree3(Tif, nil, (yyvsp[-3].tree), (yyvsp[-2].tree)); }
-#line 1173 "sys/cmd/rc/parse.c"
+#line 1449 "sys/cmd/rc/parse.c"
+    break;
+
+  case 16: /* assign: executable '=' word  */
+#line 66 "sys/cmd/rc/syntax.y"
+                        { (yyval.tree) = maketree2('=', (yyvsp[-2].tree), (yyvsp[0].tree)); }
+#line 1455 "sys/cmd/rc/parse.c"
     break;
 
-  case 16: /* cmd: %empty  */
-#line 67 "sys/cmd/rc/syntax.y"
+  case 17: /* cmd: %empty  */
+#line 69 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = nil; }
-#line 1179 "sys/cmd/rc/parse.c"
+#line 1461 "sys/cmd/rc/parse.c"
     break;
 
-  case 17: /* cmd: basic  */
-#line 68 "sys/cmd/rc/syntax.y"
+  case 18: /* cmd: basic  */
+#line 70 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = maketree1(Tbasic, (yyvsp[0].tree)); }
-#line 1185 "sys/cmd/rc/parse.c"
+#line 1467 "sys/cmd/rc/parse.c"
     break;
 
-  case 19: /* cmd: Tif paren nl ifbody  */
-#line 70 "sys/cmd/rc/syntax.y"
+  case 20: /* cmd: assign cmd  */
+#line 72 "sys/cmd/rc/syntax.y"
+                          { (yyval.tree) = hangchild1((yyvsp[-1].tree), (yyvsp[0].tree), 2); }
+#line 1473 "sys/cmd/rc/parse.c"
+    break;
+
+  case 21: /* cmd: Tif paren nl ifbody  */
+#line 73 "sys/cmd/rc/syntax.y"
                           { (yyval.tree) = hangchild1((yyvsp[-2].tree), (yyvsp[-3].tree), 0); }
-#line 1191 "sys/cmd/rc/parse.c"
+#line 1479 "sys/cmd/rc/parse.c"
     break;
 
-  case 21: /* basic: basic word  */
-#line 74 "sys/cmd/rc/syntax.y"
+  case 23: /* basic: basic word  */
+#line 77 "sys/cmd/rc/syntax.y"
              { (yyval.tree) = maketree2(Targs, (yyvsp[-1].tree), (yyvsp[0].tree)); }
-#line 1197 "sys/cmd/rc/parse.c"
+#line 1485 "sys/cmd/rc/parse.c"
     break;
 
-  case 23: /* atom: keyword  */
-#line 84 "sys/cmd/rc/syntax.y"
+  case 25: /* atom: keyword  */
+#line 87 "sys/cmd/rc/syntax.y"
               { (yyval.tree) = maketree1(Tword, (yyvsp[0].tree)); }
-#line 1203 "sys/cmd/rc/parse.c"
+#line 1491 "sys/cmd/rc/parse.c"
     break;
 
-  case 25: /* word: word '^' atom  */
-#line 88 "sys/cmd/rc/syntax.y"
+  case 27: /* word: word '^' atom  */
+#line 91 "sys/cmd/rc/syntax.y"
                 { (yyval.tree) = maketree2('^', (yyvsp[-2].tree), (yyvsp[0].tree)); }
-#line 1209 "sys/cmd/rc/parse.c"
+#line 1497 "sys/cmd/rc/parse.c"
     break;
 
-  case 27: /* executable: executable '^' atom  */
-#line 92 "sys/cmd/rc/syntax.y"
+  case 29: /* executable: executable '^' atom  */
+#line 95 "sys/cmd/rc/syntax.y"
                       { (yyval.tree) = maketree2('^', (yyvsp[-2].tree), (yyvsp[0].tree)); }
-#line 1215 "sys/cmd/rc/parse.c"
+#line 1503 "sys/cmd/rc/parse.c"
     break;
 
-  case 29: /* nonkeyword: '$' atom  */
-#line 96 "sys/cmd/rc/syntax.y"
+  case 31: /* nonkeyword: '$' atom  */
+#line 99 "sys/cmd/rc/syntax.y"
            { (yyval.tree) = maketree1('$', (yyvsp[0].tree)); }
-#line 1221 "sys/cmd/rc/parse.c"
+#line 1509 "sys/cmd/rc/parse.c"
     break;
 
 
-#line 1225 "sys/cmd/rc/parse.c"
+#line 1513 "sys/cmd/rc/parse.c"
 
       default: break;
     }
@@ -1268,7 +1556,37 @@ yyerrlab:
   if (!yyerrstatus)
     {
       ++yynerrs;
-      yyerror (YY_("syntax error"));
+      {
+        yypcontext_t yyctx
+          = {yyssp, yytoken};
+        char const *yymsgp = YY_("syntax error");
+        int yysyntax_error_status;
+        yysyntax_error_status = yysyntax_error (&yymsg_alloc, &yymsg, &yyctx);
+        if (yysyntax_error_status == 0)
+          yymsgp = yymsg;
+        else if (yysyntax_error_status == -1)
+          {
+            if (yymsg != yymsgbuf)
+              YYSTACK_FREE (yymsg);
+            yymsg = YY_CAST (char *,
+                             YYSTACK_ALLOC (YY_CAST (YYSIZE_T, yymsg_alloc)));
+            if (yymsg)
+              {
+                yysyntax_error_status
+                  = yysyntax_error (&yymsg_alloc, &yymsg, &yyctx);
+                yymsgp = yymsg;
+              }
+            else
+              {
+                yymsg = yymsgbuf;
+                yymsg_alloc = sizeof yymsgbuf;
+                yysyntax_error_status = YYENOMEM;
+              }
+          }
+        yyerror (yymsgp);
+        if (yysyntax_error_status == YYENOMEM)
+          YYNOMEM;
+      }
     }
 
   if (yyerrstatus == 3)
@@ -1410,9 +1728,10 @@ yyreturnlab:
   if (yyss != yyssa)
     YYSTACK_FREE (yyss);
 #endif
-
+  if (yymsg != yymsgbuf)
+    YYSTACK_FREE (yymsg);
   return yyresult;
 }
 
-#line 104 "sys/cmd/rc/syntax.y"
+#line 107 "sys/cmd/rc/syntax.y"
 
diff --git a/sys/cmd/rc/parse.h b/sys/cmd/rc/parse.h
index 5328340..8fc661f 100644
--- a/sys/cmd/rc/parse.h
+++ b/sys/cmd/rc/parse.h
@@ -85,7 +85,7 @@ extern int yydebug;
 #if ! defined YYSTYPE && ! defined YYSTYPE_IS_DECLARED
 union YYSTYPE
 {
-#line 20 "sys/cmd/rc/syntax.y"
+#line 22 "sys/cmd/rc/syntax.y"
 
     struct Tree *tree;
 
diff --git a/sys/cmd/rc/prompt.c b/sys/cmd/rc/prompt.c
index 21078e8..94022ca 100644
--- a/sys/cmd/rc/prompt.c
+++ b/sys/cmd/rc/prompt.c
@@ -6,11 +6,11 @@ prompt(ushort *flag)
     int f = *flag;
     if(f){
         if(!readline("> ")){
-            proc->flag.eof = 1;
+            runner->flag.eof = 1;
             return 0;
         }
 
-        proc->line++;
+        runner->line++;
         *flag = 0;
     }
     return 1;
diff --git a/sys/cmd/rc/rc.h b/sys/cmd/rc/rc.h
index 9c6307f..ef7c18e 100644
--- a/sys/cmd/rc/rc.h
+++ b/sys/cmd/rc/rc.h
@@ -93,6 +93,22 @@ struct Redir
     struct Redir *link;     /* what else to do (reverse order) */
 };
 
+enum
+{
+    PNil,
+    PRun,
+    PStop,
+    PSig,
+    PAgain,
+    PDone,
+};
+
+struct WaitItem
+{
+    int    pid;
+    ushort status;
+};
+
 struct Thread
 {
     struct {
@@ -109,21 +125,19 @@ struct Thread
     Redir *redir; // list of redirections
 
     struct {
-        ushort i     : 1;
-        ushort eof   : 1;
-        ushort stop  : 1;
-        ushort done  : 1;
-        ushort again : 1;
-    } flag;    // flags for process
+        ushort i   : 1;
+        ushort eof : 1;
+    } flag;
 
     struct {
-        int len, cap, *pid;
+        ushort status;
+        int len, cap;
+        struct WaitItem *on;
     } wait;
 
     int  pid, pgid, status;
     long line;
 
-    Tree  *nodes; // memory allocation
     Thread *link; // process we return to
     Thread *next; // next job
 };
@@ -131,6 +145,7 @@ struct Thread
 struct Shell
 {
     int pid;
+    Io *err;
     int status;
     int interactive;
     Thread *jobs;
@@ -140,9 +155,7 @@ struct Shell
 // globals
 
 extern Shell shell;
-
-extern Thread *proc;
-extern Io     *errio;
+extern Thread *runner;
 extern Code   *compiled;
 
 // -----------------------------------------------------------------------
@@ -203,6 +216,7 @@ void killzombies(void);
 Thread *getjob(int, int*);
 void    addjob(Thread *);
 void    deljob(Thread *);
+void    wakeup(Thread *);
 void    report(Thread *, int);
 
 void foreground(Thread *, int);
diff --git a/sys/cmd/rc/syntax.y b/sys/cmd/rc/syntax.y
index 247cc8a..a580cb0 100644
--- a/sys/cmd/rc/syntax.y
+++ b/sys/cmd/rc/syntax.y
@@ -2,11 +2,13 @@
 %token Targs
 %token Tbasic Tparen Tblock
 
+%define parse.error verbose
+
 %{
     #include "rc.h"
 
     int  yylex(void);
-    void yyerror(char *);
+    void yyerror(const char *);
 %}
 
 /* operator precendence: lowest first */
@@ -67,6 +69,7 @@ cmd:
 /* empty */  %prec Twhile { $$ = nil; }
 | basic                   { $$ = maketree1(Tbasic, $1); }
 | block
+| assign cmd %prec Tbang  { $$ = hangchild1($1, $2, 2); }
 | Tif paren nl ifbody     { $$ = hangchild1($2, $1, 0); }
 
 basic:
diff --git a/sys/cmd/rc/var.c b/sys/cmd/rc/var.c
index 7b5d75a..5e1e90c 100644
--- a/sys/cmd/rc/var.c
+++ b/sys/cmd/rc/var.c
@@ -159,7 +159,7 @@ globalvar(char *name)
     h = hash(name, arrlen(globals));
 
     if(strcmp(name,"PATH")==0){
-        flush(errio);
+        flush(shell.err);
     }
 
     for(v = globals[h]; v; v = v->link){
@@ -175,8 +175,8 @@ Var*
 var(char *name)
 {
     Var *v;
-    if(proc){
-        for(v = proc->local; v; v=v->link)
+    if(runner){
+        for(v = runner->local; v; v=v->link)
             if(strcmp(v->name, name) == 0)
                 return v;
     }
@@ -206,7 +206,7 @@ mkenv(void)
                 nchr+=strlen(a->str)+1;     \
         }
 
-    for(v= proc->local; v; v=v->link){
+    for(v= runner->local; v; v=v->link){
         BODY
     }
     for(h=globals; h!=arrend(globals); h++){
@@ -238,7 +238,7 @@ mkenv(void)
         *p++='\0';                      \
     }
 
-    for(v=proc->local; v; v=v->link){
+    for(v=runner->local; v; v=v->link){
         BODY
     }
     for(h=globals; h!=arrend(globals); h++){
@@ -265,7 +265,7 @@ initpath(void)
     v = globalvar("PATH");
     v->update = bigpath;
 
-    flush(errio);
+    flush(shell.err);
     bigpath(v);
 }
 
diff --git a/sys/cmd/rc/wait.c b/sys/cmd/rc/wait.c
index db586cb..44ffb58 100644
--- a/sys/cmd/rc/wait.c
+++ b/sys/cmd/rc/wait.c
@@ -8,13 +8,11 @@
 struct WaitMsg
 {
     int pid;
+    int type;
     ulong time[3];
     int status;
-    int signal;
-    int suspend;
 };
 
-
 // -----------------------------------------------------------------------
 // internal
 
@@ -30,7 +28,7 @@ await(int pid4, int opt, struct WaitMsg *msg)
     for(;;){
         if((pid = wait4(pid4, &status, opt, &ru)) <= 0){
             msg->pid = 0;
-            perror("failed wait");
+            perror("failed wait4");
             return 0;
         }
 
@@ -43,8 +41,7 @@ await(int pid4, int opt, struct WaitMsg *msg)
             msg->time[1] = s;
             msg->time[2] = u+s;
             msg->status  = WEXITSTATUS(status);
-            msg->signal  = 0;
-            msg->suspend = 0;
+            msg->type    = PDone;
 
             return 1;
         }
@@ -55,8 +52,7 @@ await(int pid4, int opt, struct WaitMsg *msg)
             msg->time[1] = s;
             msg->time[2] = u+s;
             msg->status  = WCOREDUMP(status);
-            msg->signal  = 1;
-            msg->suspend = 0;
+            msg->type    = PSig;
 
             return 1;
         }
@@ -67,14 +63,27 @@ await(int pid4, int opt, struct WaitMsg *msg)
             msg->time[1] = s;
             msg->time[2] = u+s;
             msg->status  = WSTOPSIG(status);
-            msg->signal  = 0;
-            msg->suspend = 1;
+            msg->type    = PStop;
 
             return 1;
         }
     }
 }
 
+static
+int
+shouldwait(Thread *job)
+{
+    int i;
+
+    for(i=0; i<job->wait.len; i++){
+        if(job->wait.on[i].status == PRun)
+            return 1;
+    }
+
+    return 0;
+}
+
 // -----------------------------------------------------------------------
 // exported
 
@@ -90,7 +99,7 @@ havewait(Thread *job, int pid)
     int i;
 
     for(i=0; i<job->wait.len; i++)
-        if(job->wait.pid[i] == pid)
+        if(job->wait.on[i].pid == pid)
             return 1;
     return 0;
 }
@@ -100,9 +109,10 @@ addwait(Thread *job, int pid)
 {
     if(job->wait.len == job->wait.cap){
         job->wait.cap = job->wait.cap + 2;
-        job->wait.pid = erealloc(job->wait.pid, job->wait.cap*sizeof(*job->wait.pid));
+        job->wait.on  = erealloc(job->wait.on, job->wait.cap*sizeof(*job->wait.on));
     }
-    job->wait.pid[job->wait.len++] = pid;
+
+    job->wait.on[job->wait.len++] = (struct WaitItem){.pid=pid, .status=PRun};
 }
 
 void
@@ -111,8 +121,8 @@ delwait(Thread *job, int pid)
     int r, w;
 
     for(r=w=0; r < job->wait.len; r++){
-        if(job->wait.pid[r] != pid)
-            job->wait.pid[w++] = job->wait.pid[r];
+        if(job->wait.on[r].pid != pid)
+            job->wait.on[w++].pid = job->wait.on[r].pid;
     }
     job->wait.len = w;
 }
@@ -120,36 +130,63 @@ delwait(Thread *job, int pid)
 int
 waitall(Thread *job)
 {
+    int i;
     Thread *t;
     struct WaitMsg msg;
 
-    while(job->wait.len && await(-job->pgid, WUNTRACED, &msg)){
-        if(msg.pid == 0 && errno == ECHILD){
+    while(shouldwait(job) && await(-job->pgid, WUNTRACED, &msg)){
+        if(msg.pid == 0){
             perror("wait job");
             return 0;
         }
 
+        for(i=0; i < job->wait.len; i++){
+            if(job->wait.on[i].pid == msg.pid){
+                switch(msg.type){
+                case PStop:
+                    print(shell.err, "%d: suspended\n", msg.pid);
+                    job->wait.status = PStop;
+                    job->wait.on[i].status = PStop;
+                    break;
+
+                case PSig:
+                    print(shell.err, "%d: terminated by signal %d\n", msg.pid, msg.status);
+                    /* fallthrough */
+                case PDone:
+                    job->wait.on[i].status = PDone;
+                    delwait(job, msg.pid);
+                    if(!job->wait.len)
+                        job->wait.status = PDone;
+                    break;
+
+                default:
+                    fatal("%d: unrecognized message type %d\n", msg.pid, msg.type);
+                }
+                break;
+            }
+        }
+    }
+#if 0
         for(t=job; t; t=t->link){
             if(t->pid == msg.pid){
                 t->status = msg.status;
-                t->flag.stop = t->flag.done = t->flag.again = 0;
                 if(msg.suspend){
                     t->flag.stop = 1;
                 }else{
                     t->flag.done = 1;
                     if(msg.signal){
-                        print(errio, "%d: terminated by signal %d\n", msg.pid, msg.status);
+                        print(shell.err, "%d: terminated by signal %d\n", msg.pid, msg.status);
                     }
                 }
                 delwait(t, msg.pid);
                 goto outer;
             }
         }
-
         perror("waitpid");
         return 0;
     outer:;
     }
+#endif
 
     return 1;
 }
@@ -161,24 +198,21 @@ killzombies(void)
     int index, status, pid;
 
     while((pid=waitpid(-1, &status, WNOHANG))>0){
-        print(errio, "pid %d\n", pid);
-        flush(errio);
+        print(shell.err, "found zombie pid %d\n", pid);
+        flush(shell.err);
 
         job = getjob(pid, &index);
-        if(!job){
+        if(!job)
             perror("invalid pid");
-        }
-
-        job->flag.done = job->flag.stop = job->flag.again = 0;
 
         if(WIFEXITED(status))
-            job->flag.done = 1;
+            job->wait.status = PDone;
         if(WIFSTOPPED(status))
-            job->flag.stop = 1;
+            job->wait.status = PStop;
         if(WIFCONTINUED(status))
-            job->flag.again = 1;
+            job->wait.status = PAgain;
 
-        if(job->flag.done){
+        if(job->wait.status == PDone){
             report(job,index);
             deljob(job);
         }