Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!comp.vuw.ac.nz!nickson
From: nickson@comp.vuw.ac.nz (Ray Nickson)
Newsgroups: gnu.bash.bug
Subject: Re: File Name Globbing
Message-ID: <8907160207.AA22322@comp.vuw.ac.nz>
Date: 16 Jul 89 02:05:56 GMT
References: <BITBUG.89Jul14121502@lonewolf.sun.com>
Sender: daemon@tut.cis.ohio-state.edu
Distribution: gnu
Organization: GNUs Not Usenet
Lines: 156


   Date: 14 Jul 89 19:15:02 GMT
   From: bitbug@sun.COM
   Subject: File Name Globbing
   
   It seems what is desired is a variable that toggles globbing between one of
   two behaviors:
   
   The result of a globbing operation that fails causes the shell to return
   the filename substitution pattern, rather than an error, if the pattern
   is not matched, i.e.
   ...
   
   *or* a globbing operation that fails causes the shell to print a diagnostic
   and stop processing the current command or script, i.e.
   ...


All right, time for me to stick my neck out again.  The patch at the
end implements behaviour that is almost this; I despise csh's 
`No Match' whingeing so much that I refuse to make an empty glob an
error.  If this causes some scripts to hang reading stdin, then you
bought it, you pay for it.

This patch should be considered experimental; I don't intend to put it
into the installed bash here.  While I like the idea, I'm unhappy that
I had to change the globbing semantics to such an extent to make this
work comfortably; in particular, I've hacked gloobing so that the
first word of a command is _never_ globbed.  I can't think why anyone
would want the first word globbed, but still...  The reason I did this
was that `[' is a perfectly valid (and oft-used) command; perhaps the
best solution is to say that invalid (as opposed to empty) globbing
characters should be left as is.  Discussion?

Anyway, here's the patch; take it or leave it.  It gives current
behaviour when nullglobok is unset, and allows empty globs if it's
set.

-rgn
--
nickson@comp.vuw.ac.nz       ...!uunet!vuwcomp!nickson      + 64 4 721000x8593

PS: I intend to complete one more bash-hack, then revert to writing
my thesis for a week or so... :-)

--------------------cut here--------------------
*** subst.c.orig	Thu Jun 29 15:38:23 1989
--- subst.c	Sun Jul 16 13:47:59 1989
***************
*** 1227,1232 ****
--- 1227,1235 ----
    return (expand_words_1 (list, 0));
  }
  
+ /* do we accept null globs, or refuse to glob? */
+ int nullglobok = 0;
+ 
  /* The workhorse for expand_words () and expand_words_no_var ().
     First arg is LIST, a WORD_LIST of words.
     Second arg DO_VARS is non-zero if you want to do environment and
***************
*** 1315,1321 ****
      WORD_LIST *glob_list;
  
      orig_list = (WORD_LIST *)NULL;
!     tlist = new_list;
  
      if (!disallow_filename_globbing)
        {
--- 1318,1325 ----
      WORD_LIST *glob_list;
  
      orig_list = (WORD_LIST *)NULL;
!     tlist = new_list && nullglobok ? new_list->next : new_list;
!     /* nullglobok: chop off word 0 so it doesn't get globbed */
  
      if (!disallow_filename_globbing)
        {
***************
*** 1362,1369 ****
  	  
  		if (glob_list)
  		  orig_list = (WORD_LIST *)list_append (glob_list, orig_list);
! 		else
! 		  orig_list = make_word_list (copy_word (tlist->word), orig_list);
  	      }
  	    else
  	      {
--- 1366,1374 ----
  	  
  		if (glob_list)
  		  orig_list = (WORD_LIST *)list_append (glob_list, orig_list);
! 		else if (!nullglobok)
! 		  orig_list =
! 		    make_word_list (copy_word (tlist->word), orig_list);
  	      }
  	    else
  	      {
***************
*** 1379,1384 ****
--- 1384,1394 ----
  
  	    tlist = tlist->next;
  	  }
+ 	/* nullglobok: patch word 0 back on */
+ 	if (nullglobok)
+ 	  orig_list = (WORD_LIST *)
+ 	    list_append (orig_list,
+ 			 make_word_list (copy_word (new_list->word), 0));
  	dispose_words (new_list);
  	new_list = orig_list;
        }
***************
*** 1428,1434 ****
  /* Not really `extern' just `forward'. */
  extern int sv_path (), sv_mail (), sv_terminal (), sv_histsize (), sv_uids (),
    sv_ignoreeof (), sv_glob_dot_filenames (), sv_histchars (), sv_nolinks (),
!   sv_hostname_completion_file ();
  
  #ifndef NOJOBS
  extern int sv_notify ();
--- 1438,1444 ----
  /* Not really `extern' just `forward'. */
  extern int sv_path (), sv_mail (), sv_terminal (), sv_histsize (), sv_uids (),
    sv_ignoreeof (), sv_glob_dot_filenames (), sv_histchars (), sv_nolinks (),
!   sv_hostname_completion_file (), sv_nullglobok ();
  
  #ifndef NOJOBS
  extern int sv_notify ();
***************
*** 1456,1461 ****
--- 1466,1472 ----
    { "histchars", sv_histchars },
    { "nolinks", sv_nolinks },
    { "hostname_completion_file", sv_hostname_completion_file },
+   { "nullglobok", sv_nullglobok },
    { (char *)0x00, (Function *)0x00 }
  };
  
***************
*** 1475,1480 ****
--- 1486,1499 ----
  	}
        i++;
      }
+ }
+ 
+ /* what to do just after the nullglobok variable has changed */
+ sv_nullglobok ()
+ {
+   extern int nullglobok;
+   
+   nullglobok = (find_variable ("nullglobok") != 0);
  }
  
  /* What to do just after the PATH variable has changed. */