]>
Commit | Line | Data |
---|---|---|
726f6388 JA |
1 | This file is let.def, from which is created let.c. |
2 | It implements the builtin "let" in Bash. | |
3 | ||
3185942a | 4 | Copyright (C) 1987-2009 Free Software Foundation, Inc. |
726f6388 JA |
5 | |
6 | This file is part of GNU Bash, the Bourne Again SHell. | |
7 | ||
3185942a JA |
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. | |
726f6388 | 12 | |
3185942a JA |
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. | |
726f6388 | 17 | |
3185942a JA |
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/>. | |
726f6388 JA |
20 | |
21 | $BUILTIN let | |
22 | $FUNCTION let_builtin | |
23 | $PRODUCES let.c | |
24 | $SHORT_DOC let arg [arg ...] | |
3185942a JA |
25 | Evaluate arithmetic expressions. |
26 | ||
27 | Evaluate each ARG as an arithmetic expression. Evaluation is done in | |
28 | fixed-width integers with no check for overflow, though division by 0 | |
29 | is trapped and flagged as an error. The following list of operators is | |
30 | grouped into levels of equal-precedence operators. The levels are listed | |
31 | in order of decreasing precedence. | |
726f6388 | 32 | |
7117c2d2 JA |
33 | id++, id-- variable post-increment, post-decrement |
34 | ++id, --id variable pre-increment, pre-decrement | |
ccc6cda3 JA |
35 | -, + unary minus, plus |
36 | !, ~ logical and bitwise negation | |
7117c2d2 | 37 | ** exponentiation |
ccc6cda3 JA |
38 | *, /, % multiplication, division, remainder |
39 | +, - addition, subtraction | |
40 | <<, >> left and right bitwise shifts | |
41 | <=, >=, <, > comparison | |
42 | ==, != equality, inequality | |
43 | & bitwise AND | |
44 | ^ bitwise XOR | |
45 | | bitwise OR | |
46 | && logical AND | |
47 | || logical OR | |
48 | expr ? expr : expr | |
b80f6443 | 49 | conditional operator |
ccc6cda3 JA |
50 | =, *=, /=, %=, |
51 | +=, -=, <<=, >>=, | |
52 | &=, ^=, |= assignment | |
726f6388 JA |
53 | |
54 | Shell variables are allowed as operands. The name of the variable | |
7117c2d2 | 55 | is replaced by its value (coerced to a fixed-width integer) within |
726f6388 JA |
56 | an expression. The variable need not have its integer attribute |
57 | turned on to be used in an expression. | |
58 | ||
59 | Operators are evaluated in order of precedence. Sub-expressions in | |
60 | parentheses are evaluated first and may override the precedence | |
61 | rules above. | |
62 | ||
3185942a | 63 | Exit Status: |
495aee44 | 64 | If the last ARG evaluates to 0, let returns 1; let returns 0 otherwise. |
726f6388 JA |
65 | $END |
66 | ||
ccc6cda3 JA |
67 | #include <config.h> |
68 | ||
69 | #if defined (HAVE_UNISTD_H) | |
cce855bc JA |
70 | # ifdef _MINIX |
71 | # include <sys/types.h> | |
72 | # endif | |
ccc6cda3 JA |
73 | # include <unistd.h> |
74 | #endif | |
75 | ||
b80f6443 JA |
76 | #include "../bashintl.h" |
77 | ||
726f6388 | 78 | #include "../shell.h" |
ccc6cda3 | 79 | #include "common.h" |
726f6388 JA |
80 | |
81 | /* Arithmetic LET function. */ | |
ccc6cda3 | 82 | int |
726f6388 JA |
83 | let_builtin (list) |
84 | WORD_LIST *list; | |
85 | { | |
7117c2d2 | 86 | intmax_t ret; |
d166f048 | 87 | int expok; |
726f6388 | 88 | |
7117c2d2 JA |
89 | /* Skip over leading `--' argument. */ |
90 | if (list && list->word && ISOPTION (list->word->word, '-')) | |
91 | list = list->next; | |
92 | ||
ccc6cda3 | 93 | if (list == 0) |
726f6388 | 94 | { |
b80f6443 | 95 | builtin_error (_("expression expected")); |
726f6388 JA |
96 | return (EXECUTION_FAILURE); |
97 | } | |
98 | ||
ccc6cda3 | 99 | for (; list; list = list->next) |
d166f048 JA |
100 | { |
101 | ret = evalexp (list->word->word, &expok); | |
102 | if (expok == 0) | |
103 | return (EXECUTION_FAILURE); | |
104 | } | |
ccc6cda3 | 105 | |
f73dda09 | 106 | return ((ret == 0) ? EXECUTION_FAILURE : EXECUTION_SUCCESS); |
ccc6cda3 JA |
107 | } |
108 | ||
d166f048 | 109 | #ifdef INCLUDE_UNUSED |
ccc6cda3 JA |
110 | int |
111 | exp_builtin (list) | |
112 | WORD_LIST *list; | |
113 | { | |
114 | char *exp; | |
7117c2d2 JA |
115 | intmax_t ret; |
116 | int expok; | |
ccc6cda3 JA |
117 | |
118 | if (list == 0) | |
726f6388 | 119 | { |
b80f6443 | 120 | builtin_error (_("expression expected")); |
ccc6cda3 | 121 | return (EXECUTION_FAILURE); |
726f6388 JA |
122 | } |
123 | ||
ccc6cda3 | 124 | exp = string_list (list); |
d166f048 JA |
125 | ret = evalexp (exp, &expok); |
126 | (void)free (exp); | |
f73dda09 | 127 | return (((ret == 0) || (expok == 0)) ? EXECUTION_FAILURE : EXECUTION_SUCCESS); |
726f6388 | 128 | } |
d166f048 | 129 | #endif |