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+This file is let.def, from which is created let.c.
+It implements the builtin "let" in Bash.
+
+Copyright (C) 1987-2009 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 3 of the License, 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. If not, see <http://www.gnu.org/licenses/>.
+
+$BUILTIN let
+$FUNCTION let_builtin
+$PRODUCES let.c
+$SHORT_DOC let arg [arg ...]
+Evaluate arithmetic expressions.
+
+Evaluate each ARG as an arithmetic expression. Evaluation is done in
+fixed-width integers with no check for overflow, though division by 0
+is trapped and flagged as an error. The following list of operators is
+grouped into levels of equal-precedence operators. The levels are listed
+in order of decreasing precedence.
+
+ id++, id-- variable post-increment, post-decrement
+ ++id, --id variable pre-increment, pre-decrement
+ -, + unary minus, plus
+ !, ~ logical and bitwise negation
+ ** exponentiation
+ *, /, % multiplication, division, remainder
+ +, - addition, subtraction
+ <<, >> left and right bitwise shifts
+ <=, >=, <, > comparison
+ ==, != equality, inequality
+ & bitwise AND
+ ^ bitwise XOR
+ | bitwise OR
+ && logical AND
+ || logical OR
+ expr ? expr : expr
+ conditional operator
+ =, *=, /=, %=,
+ +=, -=, <<=, >>=,
+ &=, ^=, |= assignment
+
+Shell variables are allowed as operands. The name of the variable
+is replaced by its value (coerced to a fixed-width integer) within
+an expression. The variable need not have its integer attribute
+turned on to be used in an expression.
+
+Operators are evaluated in order of precedence. Sub-expressions in
+parentheses are evaluated first and may override the precedence
+rules above.
+
+Exit Status:
+If the last ARG evaluates to 0, let returns 1; let returns 0 otherwise.
+$END
+
+#include <config.h>
+
+#if defined (HAVE_UNISTD_H)
+# ifdef _MINIX
+# include <sys/types.h>
+# endif
+# include <unistd.h>
+#endif
+
+#include "../bashintl.h"
+
+#include "../shell.h"
+#include "common.h"
+
+/* Arithmetic LET function. */
+int
+let_builtin (list)
+ WORD_LIST *list;
+{
+ intmax_t ret;
+ int expok;
+
+ CHECK_HELPOPT (list);
+
+ /* Skip over leading `--' argument. */
+ if (list && list->word && ISOPTION (list->word->word, '-'))
+ list = list->next;
+
+ if (list == 0)
+ {
+ builtin_error (_("expression expected"));
+ return (EXECUTION_FAILURE);
+ }
+
+ for (; list; list = list->next)
+ {
+ ret = evalexp (list->word->word, EXP_EXPANDED, &expok);
+ if (expok == 0)
+ return (EXECUTION_FAILURE);
+ }
+
+ return ((ret == 0) ? EXECUTION_FAILURE : EXECUTION_SUCCESS);
+}
+
+#ifdef INCLUDE_UNUSED
+int
+exp_builtin (list)
+ WORD_LIST *list;
+{
+ char *exp;
+ intmax_t ret;
+ int expok;
+
+ if (list == 0)
+ {
+ builtin_error (_("expression expected"));
+ return (EXECUTION_FAILURE);
+ }
+
+ exp = string_list (list);
+ ret = evalexp (exp, EXP_EXPANDED, &expok);
+ (void)free (exp);
+ return (((ret == 0) || (expok == 0)) ? EXECUTION_FAILURE : EXECUTION_SUCCESS);
+}
+#endif