This file is shift.def, from which is created shift.c.
It implements the builtin "shift" in Bash.

Copyright (C) 1987, 1989, 1991 Free Software Foundation, Inc.

This file is part of GNU Bash, the Bourne Again SHell.

Bash is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

Bash is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License along
with Bash; see the file COPYING.  If not, write to the Free Software
Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.

$PRODUCES shift.c

#include <config.h>

#if defined (HAVE_UNISTD_H)
#  ifdef _MINIX
#    include <sys/types.h>
#  endif
#  include <unistd.h>
#endif

#include "../bashansi.h"

#include "../shell.h"
#include "common.h"

$BUILTIN shift
$FUNCTION shift_builtin
$SHORT_DOC shift [n]
The positional parameters from $N+1 ... are renamed to $1 ...  If N is
not given, it is assumed to be 1.
$END

int print_shift_error;

/* Shift the arguments ``left''.  Shift DOLLAR_VARS down then take one
   off of REST_OF_ARGS and place it into DOLLAR_VARS[9].  If LIST has
   anything in it, it is a number which says where to start the
   shifting.  Return > 0 if `times' > $#, otherwise 0. */
int
shift_builtin (list)
     WORD_LIST *list;
{
  int times;
  register int count;
  WORD_LIST *temp;

  times = get_numeric_arg (list, 0);

  if (times == 0)
    return (EXECUTION_SUCCESS);
  else if (times < 0)
    {
      builtin_error ("shift count must be >= 0");
      return (EXECUTION_FAILURE);
    }
  else if (times > number_of_args ())
    {
      if (print_shift_error)
	builtin_error ("shift count must be <= $#");
      return (EXECUTION_FAILURE);
    }

  while (times-- > 0)
    {
      if (dollar_vars[1])
	free (dollar_vars[1]);

      for (count = 1; count < 9; count++)
	dollar_vars[count] = dollar_vars[count + 1];

      if (rest_of_args)
	{
	  temp = rest_of_args;
	  dollar_vars[9] = savestring (temp->word->word);
	  rest_of_args = rest_of_args->next;
	  temp->next = (WORD_LIST *)NULL;
	  dispose_words (temp);
	}
      else
	dollar_vars[9] = (char *)NULL;
    }
  return (EXECUTION_SUCCESS);
}