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) 1987-2009 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
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation, either version 3 of the License, or
  11 (at your option) any later version.
  12
  13 Bash is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  20
  21 $PRODUCES shift.c
  22
  23 #include <config.h>
  24
  25 #if defined (HAVE_UNISTD_H)
  26 #  ifdef _MINIX
  27 #    include <sys/types.h>
  28 #  endif
  29 #  include <unistd.h>
  30 #endif
  31
  32 #include "../bashansi.h"
  33 #include "../bashintl.h"
  34
  35 #include "../shell.h"
  36 #include "common.h"
  37
  38 $BUILTIN shift
  39 $FUNCTION shift_builtin
  40 $SHORT_DOC shift [n]
  41 Shift positional parameters.
  42
  43 Rename the positional parameters $N+1,$N+2 ... to $1,$2 ...  If N is
  44 not given, it is assumed to be 1.
  45
  46 Exit Status:
  47 Returns success unless N is negative or greater than $#.
  48 $END
  49
  50 int print_shift_error;
  51
  52 /* Shift the arguments ``left''.  Shift DOLLAR_VARS down then take one
  53    off of REST_OF_ARGS and place it into DOLLAR_VARS[9].  If LIST has
  54    anything in it, it is a number which says where to start the
  55    shifting.  Return > 0 if `times' > $#, otherwise 0. */
  56 int
  57 shift_builtin (list)
  58      WORD_LIST *list;
  59 {
  60   intmax_t times;
  61   register int count;
  62   WORD_LIST *temp;
  63
  64   if (get_numeric_arg (list, 0, &times) == 0)
  65     return (EXECUTION_FAILURE);
  66
  67   if (times == 0)
  68     return (EXECUTION_SUCCESS);
  69   else if (times < 0)
  70     {
  71       sh_erange (list ? list->word->word : NULL, _("shift count"));
  72       return (EXECUTION_FAILURE);
  73     }
  74   else if (times > number_of_args ())
  75     {
  76       if (print_shift_error)
  77         sh_erange (list ? list->word->word : NULL, _("shift count"));
  78       return (EXECUTION_FAILURE);
  79     }
  80
  81   while (times-- > 0)
  82     {
  83       if (dollar_vars[1])
  84         free (dollar_vars[1]);
  85
  86       for (count = 1; count < 9; count++)
  87         dollar_vars[count] = dollar_vars[count + 1];
  88
  89       if (rest_of_args)
  90         {
  91           temp = rest_of_args;
  92           dollar_vars[9] = savestring (temp->word->word);
  93           rest_of_args = rest_of_args->next;
  94           temp->next = (WORD_LIST *)NULL;
  95           dispose_words (temp);
  96         }
  97       else
  98         dollar_vars[9] = (char *)NULL;
  99     }
 100   return (EXECUTION_SUCCESS);
 101 }