Re: *suggestion* for NULLCMD and emulate [ck]sh

[Alexandre Duret-Lutz <duret_g@xxxxxxxx>]

>>> "Bart" == Bart Schaefer <schaefer@xxxxxxxxxxxxxxxxxxxxxxx> writes:

[...]

 Bart> Rather than have zsh change the value of NULLCMD when it starts up
 Bart> as sh or ksh, the proposed SH_NULLCMD option should cause the ": >
 Bart> file" style to be used regardless of the value of NULLCMD.

 Bart> The second option, which I'd call CSH_NULLCMD for consistency, would
 Bart> also ignore the value of NULLCMD but give the "redirection with no
 Bart> command" error.

Good, I find this a lot cleaner.

 Bart> We then pick one of these to "win" when both are set, as presently
 Bart> happens with e.g. NULLGLOB and CSH_NULLGLOB.  I don't really care
 Bart> which one wins.

 Bart> Do we need something similar for READNULLCMD?  Can these same two
 Bart> options be overloaded for both at once?  If the answers are "yes"
 Bart> and "no" then I think the right thing is to not change it at all, as
 Bart> it's just too sloppy to get it right.  If the first is "no" or the
 Bart> second is "yes," go ahead.

You would answer 1:no, 2:yes.  I think there is no point trying to emulate
for instance sh for input and csh for ouput.  And should you really want to
do this, you could unset both {,C}SH_NULLCMD and play with the
{,READ}NULLCMD parameters as before.

Adapted patch that supersede 9617 below.

Index: Src/zsh.h
--- Src/zsh.h Thu, 03 Feb 2000 00:03:47 +0100 Alexandre
+++ Src/zsh.h Tue, 08 Feb 2000 22:43:05 +0100 Alexandre
@@ -1269,6 +1269,7 @@
     CSHJUNKIEHISTORY,
     CSHJUNKIELOOPS,
     CSHJUNKIEQUOTES,
+    CSHNULLCMD,
     CSHNULLGLOB,
     EQUALS,
     ERREXIT,
@@ -1352,6 +1353,7 @@
     SHFILEEXPANSION,
     SHGLOB,
     SHINSTDIN,
+    SHNULLCMD,
     SHOPTIONLETTERS,
     SHORTLOOPS,
     SHWORDSPLIT,
Index: Src/options.c
--- Src/options.c Fri, 31 Dec 1999 13:32:44 +0100 Alexandre
+++ Src/options.c Tue, 08 Feb 2000 22:43:58 +0100 Alexandre
@@ -102,6 +102,7 @@
 {NULL, "cshjunkiehistory",    OPT_EMULATE|OPT_CSH,	 CSHJUNKIEHISTORY},
 {NULL, "cshjunkieloops",      OPT_EMULATE|OPT_CSH,	 CSHJUNKIELOOPS},
 {NULL, "cshjunkiequotes",     OPT_EMULATE|OPT_CSH,	 CSHJUNKIEQUOTES},
+{NULL, "cshnullcmd",	      OPT_EMULATE|OPT_CSH,	 CSHNULLCMD},
 {NULL, "cshnullglob",	      OPT_EMULATE|OPT_CSH,	 CSHNULLGLOB},
 {NULL, "equals",	      OPT_EMULATE|OPT_ZSH,	 EQUALS},
 {NULL, "errexit",	      OPT_EMULATE,		 ERREXIT},
@@ -185,6 +186,7 @@
 {NULL, "shfileexpansion",     OPT_EMULATE|OPT_BOURNE,	 SHFILEEXPANSION},
 {NULL, "shglob",	      OPT_EMULATE|OPT_BOURNE,	 SHGLOB},
 {NULL, "shinstdin",	      OPT_SPECIAL,		 SHINSTDIN},
+{NULL, "shnullcmd",           OPT_EMULATE|OPT_BOURNE,	 SHNULLCMD},
 {NULL, "shoptionletters",     OPT_EMULATE|OPT_BOURNE,	 SHOPTIONLETTERS},
 {NULL, "shortloops",	      OPT_EMULATE|OPT_NONBOURNE, SHORTLOOPS},
 {NULL, "shwordsplit",	      OPT_EMULATE|OPT_BOURNE,	 SHWORDSPLIT},
Index: Src/init.c
--- Src/init.c Mon, 07 Feb 2000 17:48:28 +0100 Alexandre
+++ Src/init.c Tue, 08 Feb 2000 22:41:05 +0100 Alexandre
@@ -666,17 +666,8 @@
     mypid = (zlong) getpid();
     term  = ztrdup("");
 
-    /* The following variable assignments cause zsh to behave more *
-     * like Bourne and Korn shells when invoked as "sh" or "ksh".  *
-     * NULLCMD=":" and READNULLCMD=":"                             */
-
-    if (emulation == EMULATE_KSH || emulation == EMULATE_SH) {
-	nullcmd     = ztrdup(":");
-	readnullcmd = ztrdup(":");
-    } else {
-	nullcmd     = ztrdup("cat");
-	readnullcmd = ztrdup("more");
-    }
+    nullcmd     = ztrdup("cat");
+    readnullcmd = ztrdup("more");
 
     /* We cache the uid so we know when to *
      * recheck the info for `USERNAME'     */
Index: Src/exec.c
--- Src/exec.c Tue, 08 Feb 2000 10:59:23 +0100 Alexandre
+++ Src/exec.c Tue, 08 Feb 2000 22:46:41 +0100 Alexandre
@@ -1661,11 +1661,15 @@
 		    } else if (varspc) {
 			nullexec = 2;
 			break;
-		    } else if (!nullcmd || !*nullcmd ||
+		    } else if (!nullcmd || !*nullcmd || opts[CSHNULLCMD] ||
 			       (cflags & BINF_PREFIX)) {
 			zerr("redirection with no command", NULL, 0);
 			errflag = lastval = 1;
 			return;
+		    } else if (!nullcmd || !*nullcmd || opts[SHNULLCMD]) {
+			if (!args)
+			    args = newlinklist();
+			addlinknode(args, dupstring(":"));
 		    } else if (readnullcmd && *readnullcmd &&
 			       ((Redir) peekfirst(redir))->type == READ &&
 			       !nextnode(firstnode(redir))) {
Index: Doc/Zsh/redirect.yo
--- Doc/Zsh/redirect.yo Fri, 31 Dec 1999 13:32:44 +0100 Alexandre
+++ Doc/Zsh/redirect.yo Tue, 08 Feb 2000 23:09:25 +0100 Alexandre
@@ -198,20 +198,28 @@
 sect(Redirections with no command)
 vindex(NULLCMD, use of)
 vindex(READNULLCMD, use of)
-If a simple command consists of one or more redirection operators
-and zero or more parameter assignments, but no command name, and the
-parameter tt(NULLCMD) is not set, an error is caused.  If the parameter
-tt(NULLCMD) is set, its value will be inserted as a command with the
-given redirections.  If both tt(NULLCMD) and tt(READNULLCMD) are set, then
-the value of the latter will be used instead of that of the former when the
-redirection is an input.  The default for tt(NULLCMD) is `tt(cat)' and for
-tt(READNULLCMD) is `tt(more)'. Thus
+pindex(IGNORE_NULLCMD, use of)
+pindex(SH_NULLCMD, use of)
+When a simple command consists of one or more redirection operators
+and zero or more parameter assignments, but no command name, zsh can
+behave in several ways.
+
+If the parameter tt(NULLCMD) is not set or the option tt(CSH_NULLCMD) is
+set, an error is caused.  This is the bf(csh) behavior and tt(CSH_NULLCMD)
+is set by default when emulating bf(csh).
+
+If the option (SH_NULLCMD) is set, the builtin tt(`:') is inserted as a
+command with the given redirections.  This is the default when emulating
+bf(sh) or bf(ksh).
+
+Otherwise, if the parameter tt(NULLCMD) is set, its value will be used as a
+command with the given redirections.  If both tt(NULLCMD) and
+tt(READNULLCMD) are set, then the value of the latter will be used instead
+of that of the former when the redirection is an input.  The default for
+tt(NULLCMD) is `tt(cat)' and for tt(READNULLCMD) is `tt(more)'. Thus
 
 example(< file)
 
 shows the contents of tt(file) on standard output, with paging if that is a
 terminal.  tt(NULLCMD) and tt(READNULLCMD) may refer to shell functions.
 
-The standard Bourne shell behaviour is obtained by setting tt(NULLCMD) and
-tt(READNULLCMD) to `tt(:)'.  This is the default when zsh is emulating bf(sh)
-or bf(ksh).
Index: Doc/Zsh/options.yo
--- Doc/Zsh/options.yo Fri, 31 Dec 1999 13:32:44 +0100 Alexandre
+++ Doc/Zsh/options.yo Tue, 08 Feb 2000 23:18:52 +0100 Alexandre
@@ -305,6 +305,16 @@
 or `tt(")' (and `tt(\)' itself no longer needs escaping).
 Command substitutions are only expanded once, and cannot be nested.
 )
+pindex(CSH_NULLCMD)
+vindex(NULLCMD, ignoring)
+vindex(READNULLCMD, ignoring)
+cindex(redirections with no command, csh)
+cindex(csh, redirections with no command)
+item(tt(IGNORE_NULLCMD) <C>)(
+Do not use the values of tt(NULLCMD) and tt(READNULLCMD) 
+when running redirections with no command.  This make 
+such redirections fail (see noderef(Redirection)).
+)
 pindex(CSH_NULL_GLOB)
 cindex(csh, null globbing style)
 cindex(null globbing style, csh)
@@ -976,7 +986,19 @@
 necessarily affect the state the option will have while the shell is
 running - that is purely an indicator of whether on not commands are
 em(actually) being read from standard input.
-The value of this option cannot be changed anywhere other than the command line.
+The value of this option cannot be changed anywhere other 
+than the command line.
+)
+pindex(SH_NULLCMD)
+vindex(NULLCMD, ignoring)
+vindex(READNULLCMD, ignoring)
+cindex(sh, redirections with no command)
+cindex(ksh, redirections with no command)
+cindex(redirections with no command, sh)
+cindex(redirections with no command, ksh)
+item(tt(SH_NULLCMD) <K> <S>)(
+Do not use the values of tt(NULLCMD) and tt(READNULLCMD) 
+when doing redirections, use `tt(:)' instead (see noderef(Redirection)).
 )
 pindex(SH_OPTION_LETTERS)
 cindex(sh, single letter options style)

-- 
Alexandre Duret-Lutz