builtins/shift.def

   1 This file is shift.def, from which is created shift.c.
   2 It implements the builtin "shift" in Bash.
   3
   4 Copyright (C) 1987-2002 Free Software Foundation, Inc.
   5
   6 This file is part of GNU Bash, the Bourne Again SHell.
   7
   8 Bash is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 2, or (at your option) any later
  11 version.
  12
  13 Bash is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License along
  19 with Bash; see the file COPYING.  If not, write to the Free Software
  20 Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.
  21
  22 $PRODUCES shift.c
  23
  24 #include <config.h>
  25
  26 #if defined (HAVE_UNISTD_H)
  27 #  ifdef _MINIX
  28 #    include <sys/types.h>
  29 #  endif
  30 #  include <unistd.h>
  31 #endif
  32
  33 #include "../bashansi.h"
  34
  35 #include "../shell.h"
  36 #include "common.h"
  37
  38 $BUILTIN shift
  39 $FUNCTION shift_builtin
  40 $SHORT_DOC shift [n]
  41 The positional parameters from $N+1 ... are renamed to $1 ...  If N is
  42 not given, it is assumed to be 1.
  43 $END
  44
  45 int print_shift_error;
  46
  47 /* Shift the arguments ``left''.  Shift DOLLAR_VARS down then take one
  48    off of REST_OF_ARGS and place it into DOLLAR_VARS[9].  If LIST has
  49    anything in it, it is a number which says where to start the
  50    shifting.  Return > 0 if `times' > $#, otherwise 0. */
  51 int
  52 shift_builtin (list)
  53      WORD_LIST *list;
  54 {
  55   intmax_t times;
  56   register int count;
  57   WORD_LIST *temp;
  58
  59   times = get_numeric_arg (list, 0);
  60
  61   if (times == 0)
  62     return (EXECUTION_SUCCESS);
  63   else if (times < 0)
  64     {
  65       sh_erange (list->word->word, "shift count");
  66       return (EXECUTION_FAILURE);
  67     }
  68   else if (times > number_of_args ())
  69     {
  70       if (print_shift_error)
  71         sh_erange (list->word->word, "shift count");
  72       return (EXECUTION_FAILURE);
  73     }
  74
  75   while (times-- > 0)
  76     {
  77       if (dollar_vars[1])
  78         free (dollar_vars[1]);
  79
  80       for (count = 1; count < 9; count++)
  81         dollar_vars[count] = dollar_vars[count + 1];
  82
  83       if (rest_of_args)
  84         {
  85           temp = rest_of_args;
  86           dollar_vars[9] = savestring (temp->word->word);
  87           rest_of_args = rest_of_args->next;
  88           temp->next = (WORD_LIST *)NULL;
  89           dispose_words (temp);
  90         }
  91       else
  92         dollar_vars[9] = (char *)NULL;
  93     }
  94   return (EXECUTION_SUCCESS);
  95 }