whence following symlinks

["Juergen A. Erhard" <jae@xxxxxxxxxxxx>]

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My first zsh hack.

Ever did a 'which sh', and wondered whether '/bin/sh' was REALLY just
'/bin/sh' or not, rather, '/bin/bash'... honest, how many systems do
YOU know that have a '/bin/sh'? Is your's NOT linked to '/bin/zsh'?
Shame on you ;-)

Okay. Now with this patch, 'which -s' follows symlinks and prints
them, separated by ' -> ', after the first path found.

Unfortunately, 'whence -ms' doesn't work as expected, because '-m'
jumps to a different code section, and that code doesn't care for
'-s'.

To get 'whence -ms', do something like this

  whence -m '*sh' | sed 's/.*/whence -s 

This at least works for me.

Another thing missing is checking for hard links... but that is a lot
more complicated, next to impossible. At least we might check whether
the path found has more than one name (hard links > 1), to give the
user an idea that this might not be what it seems to be.

And now, here's the patch, done with 'diff -cp', relative to zsh 3.1.0.

Enjoy -- JAE

*** hashtable.h	1997/03/19 09:45:12	1.1
- --- hashtable.h	1997/03/19 10:07:07
*************** struct builtin builtins[] =
*** 338,346 ****
      {NULL, "unset", BINF_PSPECIAL, bin_unset, 1, -1, 0, "fm", NULL},
      {NULL, "unsetopt", 0, bin_setopt, 0, -1, BIN_UNSETOPT, NULL, NULL},
      {NULL, "wait", 0, bin_fg, 0, -1, BIN_WAIT, NULL, NULL},
!     {NULL, "whence", 0, bin_whence, 0, -1, 0, "acmpvf", NULL},
      {NULL, "where", 0, bin_whence, 0, -1, 0, "pm", "ca"},
!     {NULL, "which", 0, bin_whence, 0, -1, 0, "amp", "c"},
      {NULL, NULL}
  };
  #else
- --- 338,346 ----
      {NULL, "unset", BINF_PSPECIAL, bin_unset, 1, -1, 0, "fm", NULL},
      {NULL, "unsetopt", 0, bin_setopt, 0, -1, BIN_UNSETOPT, NULL, NULL},
      {NULL, "wait", 0, bin_fg, 0, -1, BIN_WAIT, NULL, NULL},
!     {NULL, "whence", 0, bin_whence, 0, -1, 0, "acmpvfs", NULL},
      {NULL, "where", 0, bin_whence, 0, -1, 0, "pm", "ca"},
!     {NULL, "which", 0, bin_whence, 0, -1, 0, "amps", "c"},
      {NULL, NULL}
  };
  #else
*** builtin.c	1997/03/19 07:48:38	1.1
- --- builtin.c	1997/04/09 15:09:10
***************
*** 2244,2252 ****
  	} else if ((cnam = findcmd(*argv))) {
  	    /* Found external command. */
  	    if (v && !csh)
! 		printf("%s is %s\n", *argv, cnam);
  	    else
! 		puts(cnam);
  	    zsfree(cnam);
  	} else {
  	    /* Not found at all. */
- --- 2244,2278 ----
  	} else if ((cnam = findcmd(*argv))) {
  	    /* Found external command. */
  	    if (v && !csh)
! 		printf("%s is %s", *argv, cnam);
  	    else
! 		fputs(cnam,stdout);
! 
! 	    /* now check symlinks if -s given */
! 	    if (ops['s']) {
! 		/* temporary vars for this if */
! 		char *try_link;
! 		int chase;
! 		
! 		/* temporarily set CHASELINKS */
! 		chase = isset(CHASELINKS);
! 		dosetopt(CHASELINKS, 1, 0);
! 		
! 		/* get possible link */
! 		try_link = xsymlink(cnam);
! 
! 		/* if it is one (different from cnam), print it */
! 		if (strcmp(cnam,try_link)!=0)
! 		    printf(" -> %s",try_link);
! 		
! 		/* revert setting of CHASELINKS */
! 		dosetopt(CHASELINKS, chase, 0);
! 
! 		/* throw away try_link... hope this is the right fn */
! 		zsfree(try_link);
! 	    }
! 
! 	    fputc('\n',stdout);
  	    zsfree(cnam);
  	} else {
  	    /* Not found at all. */

- -- 
Juergen A. Erhard (that ue is actually \"u (TeX) or ü (HTML/SGML))
eMail: jae@xxxxxxxxxxxx                             |
snailMail: Belfortstr. 6; 76133 Karlsruhe; GERMANY  |  pros do it for money,
phone: +49 721 27326                                |  amateurs out of love.
WWW: http://members.tripod.com/~Juergen_Erhard/  (under construction!)

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