1This file is shift.def, from which is created shift.c.
2It implements the builtin "shift" in Bash.
3
4Copyright (C) 1987-2020 Free Software Foundation, Inc.
5
6This file is part of GNU Bash, the Bourne Again SHell.
7
8Bash is free software: you can redistribute it and/or modify
9it under the terms of the GNU General Public License as published by
10the Free Software Foundation, either version 3 of the License, or
11(at your option) any later version.
12
13Bash is distributed in the hope that it will be useful,
14but WITHOUT ANY WARRANTY; without even the implied warranty of
15MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16GNU General Public License for more details.
17
18You should have received a copy of the GNU General Public License
19along 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]
41Shift positional parameters.
42
43Rename the positional parameters $N+1,$N+2 ... to $1,$2 ...  If N is
44not given, it is assumed to be 1.
45
46Exit Status:
47Returns success unless N is negative or greater than $#.
48$END
49
50int 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. */
56int
57shift_builtin (list)
58     WORD_LIST *list;
59{
60  intmax_t times;
61  int itimes, nargs;
62
63  CHECK_HELPOPT (list);
64
65  if (get_numeric_arg (list, 0, &times) == 0)
66    return (EXECUTION_FAILURE);
67
68  if (times == 0)
69    return (EXECUTION_SUCCESS);
70  else if (times < 0)
71    {
72      sh_erange (list ? list->word->word : NULL, _("shift count"));
73      return (EXECUTION_FAILURE);
74    }
75  nargs = number_of_args ();
76  if (times > nargs)
77    {
78      if (print_shift_error)
79	sh_erange (list ? list->word->word : NULL, _("shift count"));
80      return (EXECUTION_FAILURE);
81    }
82  else if (times == nargs)
83    clear_dollar_vars ();
84  else
85    shift_args (itimes = times);
86
87  invalidate_cached_quoted_dollar_at ();
88
89  return (EXECUTION_SUCCESS);
90}
91