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To: zsh-workers@sunsite.auc.dk (Zsh hackers list)
Subject: PATCH: pws-25: parameter assignment with redirection
Date: Mon, 05 Jul 1999 16:41:41 +0200
From: Peter Stephenson <pws@ibmth.df.unipi.it>

This

  foo=bar >&/dev/null

is interpreted as a redirection which uses $NULLCMD to write to /dev/null.
I would interpret it as a parameter assigment with the output redirected so
that error messages about bad patterns and so forth don't appear.  This
patch does that.

--- Src/exec.c.av	Mon Jul  5 13:16:12 1999
+++ Src/exec.c	Mon Jul  5 16:38:12 1999
@@ -1532,6 +1532,9 @@
 			/* Was this "exec < foobar"? */
 			nullexec = 1;
 			break;
+		    } else if (vars && nonempty(vars)) {
+			nullexec = 2;
+			break;
 		    } else if (!nullcmd || !*nullcmd ||
 			       (cflags & BINF_PREFIX)) {
 			zerr("redirection with no command", NULL, 0);
@@ -1871,7 +1874,8 @@
 		addfd(forked, save, mfds, fn->fd1, fil, 0);
 		/* If this is 'exec < file', read from stdin, *
 		 * not terminal, unless `file' is a terminal. */
-		if (nullexec && fn->fd1 == 0 && isset(SHINSTDIN) && interact)
+		if (nullexec == 1 && fn->fd1 == 0 &&
+		    isset(SHINSTDIN) && interact)
 		    init_io();
 		break;
 	    case CLOSE:
@@ -1931,17 +1935,28 @@
 	closemn(mfds, i);
 
     if (nullexec) {
-	for (i = 0; i < 10; i++)
-	    if (save[i] != -2)
-		zclose(save[i]);
+	if (nullexec == 1) {
+	    /*
+	     * If nullexec is 1 we specifically *don't* restore the original
+	     * fd's before returning.
+	     */
+	    for (i = 0; i < 10; i++)
+		if (save[i] != -2)
+		    zclose(save[i]);
+	    return;
+	}
 	/*
-	 * Here we specifically *don't* restore the original fd's
-	 * before returning.
+	 * If nullexec is 2, we have variables to add with the redirections
+	 * in place.
 	 */
-	return;
-    }
-
-    if (isset(EXECOPT) && !errflag) {
+	if (vars)
+	    addvars(vars, 0);
+	lastval = errflag ? errflag : cmdoutval;
+	if (isset(XTRACE)) {
+	    fputc('\n', stderr);
+	    fflush(stderr);
+	}
+    } else if (isset(EXECOPT) && !errflag) {
 	/*
 	 * We delay the entersubsh() to here when we are exec'ing
 	 * the current shell (including a fake exec to run a builtin then

-- 
Peter Stephenson <pws@ibmth.df.unipi.it>       Tel: +39 050 844536
WWW:  http://www.ifh.de/~pws/
Dipartimento di Fisica, Via Buonarroti 2, 56127 Pisa, Italy