Plan 9's rc.

not a clear win over byron's,
but at least it has the right syntax.

src/cmd/rc/here.c

@@ -0,0 +1,131 @@
+#include "rc.h"
+#include "exec.h"
+#include "io.h"
+#include "fns.h"
+struct here *here, **ehere;
+int ser=0;
+char tmp[]="/tmp/here0000.0000";
+char hex[]="0123456789abcdef";
+void psubst(io*, char*);
+void pstrs(io*, word*);
+void hexnum(char *p, int n)
+{
+	*p++=hex[(n>>12)&0xF];
+	*p++=hex[(n>>8)&0xF];
+	*p++=hex[(n>>4)&0xF];
+	*p=hex[n&0xF];
+}
+tree *heredoc(tree *tag)
+{
+	struct here *h=new(struct here);
+	if(tag->type!=WORD) yyerror("Bad here tag");
+	h->next=0;
+	if(here)
+		*ehere=h;
+	else
+		here=h;
+	ehere=&h->next;
+	h->tag=tag;
+	hexnum(&tmp[9], getpid());
+	hexnum(&tmp[14], ser++);
+	h->name=strdup(tmp);
+	return token(tmp, WORD);
+}
+/*
+ * bug: lines longer than NLINE get split -- this can cause spurious
+ * missubstitution, or a misrecognized EOF marker.
+ */
+#define	NLINE	4096
+void readhere(void){
+	struct here *h, *nexth;
+	io *f;
+	char *s, *tag;
+	int c, subst;
+	char line[NLINE+1];
+	for(h=here;h;h=nexth){
+		subst=!h->tag->quoted;
+		tag=h->tag->str;
+		c=Creat(h->name);
+		if(c<0) yyerror("can't create here document");
+		f=openfd(c);
+		s=line;
+		pprompt();
+		while((c=rchr(runq->cmdfd))!=EOF){
+			if(c=='\n' || s==&line[NLINE]){
+				*s='\0';
+				if(strcmp(line, tag)==0) break;
+				if(subst) psubst(f, line);
+				else pstr(f, line);
+				s=line;
+				if(c=='\n'){
+					pprompt();
+					pchr(f, c);
+				}
+				else *s++=c;
+			}
+			else *s++=c;
+		}
+		flush(f);
+		closeio(f);
+		cleanhere(h->name);
+		nexth=h->next;
+		efree((char *)h);
+	}
+	here=0;
+	doprompt=1;
+}
+void psubst(io *f, char *s)
+{
+	char *t, *u;
+	int savec, n;
+	word *star;
+	while(*s){
+		if(*s!='$'){
+			if(0xa0<=(*s&0xff) && (*s&0xff)<=0xf5){
+				pchr(f, *s++);
+				if(*s=='\0') break;
+			}
+			else if(0xf6<=(*s&0xff) && (*s&0xff)<=0xf7){
+				pchr(f, *s++);
+				if(*s=='\0') break;
+				pchr(f, *s++);
+				if(*s=='\0') break;
+			}
+			pchr(f, *s++);
+		}
+		else{
+			t=++s;
+			if(*t=='$') pchr(f, *t++);
+			else{
+				while(*t && idchr(*t)) t++;
+				savec=*t;
+				*t='\0';
+				n=0;
+				for(u=s;*u && '0'<=*u && *u<='9';u++) n=n*10+*u-'0';
+				if(n && *u=='\0'){
+					star=vlook("*")->val;
+					if(star && 1<=n && n<=count(star)){
+						while(--n) star=star->next;
+						pstr(f, star->word);
+					}
+				}
+				else
+					pstrs(f, vlook(s)->val);
+				*t=savec;
+				if(savec=='^') t++;
+			}
+			s=t;
+		}
+	}
+}
+void pstrs(io *f, word *a)
+{
+	if(a){
+		while(a->next && a->next->word){
+			pstr(f, a->word);
+			pchr(f, ' ');
+			a=a->next;
+		}
+		pstr(f, a->word);
+	}
+}