Difference between revisions of "Let (bash)"
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[heth@mars ~]$ <input>help let</input> | [heth@mars ~]$ <input>help let</input> | ||
let: let arg [arg ...] | let: let arg [arg ...] | ||
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If the last ARG evaluates to 0, let returns 1; 0 is returned | If the last ARG evaluates to 0, let returns 1; 0 is returned | ||
otherwise. | otherwise. | ||
− | </ | + | </source> |
− | {{ | + | {{Source cli}} |
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[[category:bash]] | [[category:bash]] |
Latest revision as of 17:28, 28 February 2010
[heth@mars ~]$ <input>help let</input>
let: let arg [arg ...]
Each ARG is an arithmetic expression to be evaluated. 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.
If the last ARG evaluates to 0, let returns 1; 0 is returned
otherwise.