问个出处((result=$result|2))

我是DBA

if [ $? != 0  ] ; then
        ((result=$result|4))
fi



if (($a&4))
then
        /usr/sbin/triggerwkb 2>/dev/null &
fi




这里的|以及&是做什么计算？以前没见过，man里怎么查？
没懂啊。

ly5066113

bash:
bitwise operators. The bitwise operators seldom make an appearance in shell scripts. Their chief use seems to be manipulating and testing values read from ports or sockets. "Bit flipping" is more relevant to compiled languages, such as C and C++, which run fast enough to permit its use on the fly.

bitwise operators

<<

    bitwise left shift (multiplies by 2 for each shift position)
<<=

    "left-shift-equal"

    let "var <<= 2" results in var left-shifted 2 bits (multiplied by 4)
>>

    bitwise right shift (divides by 2 for each shift position)
>>=

    "right-shift-equal" (inverse of <<=)
&

    bitwise and
&=

    "bitwise and-equal"
|

    bitwise OR
|=

    "bitwise OR-equal"
~

    bitwise negate
!

    bitwise NOT
^

    bitwise XOR
^=

    "bitwise XOR-equal"

我是DBA

不是很懂，tim给讲一下吧。

waker

1. ARITHMETIC EVALUATION
   
2.        The shell allows arithmetic expressions to be evaluated, under certain
   
3.        circumstances (see the let and declare builtin commands and Arithmetic
   
4.        Expansion).   Evaluation is done in fixed-width integers with no check
   
5.        for overflow, though division by 0 is trapped and flagged as an error.
   
6.        The  operators and their precedence, associativity, and values are the
   
7.        same as in the C language.  The following list of operators is grouped
   
8.        into  levels  of equal-precedence operators.  The levels are listed in
   
9.        order of decreasing precedence.
   
10. 
    
11.        id++ id--
    
12.               variable post-increment and post-decrement
    
13.        ++id --id
    
14.               variable pre-increment and pre-decrement
    
15.        - +    unary minus and plus
    
16.        ! ~    logical and bitwise negation
    
17.        **     exponentiation
    
18.        * / %  multiplication, division, remainder
    
19.        + -    addition, subtraction
    
20.        << >>  left and right bitwise shifts
    
21.        <= >= < >
    
22.               comparison
    
23.        == !=  equality and inequality
    
24.        &      bitwise AND
    
25.        ^      bitwise exclusive OR
    
26.        |      bitwise OR
    
27.        &&     logical AND
    
28.        ||     logical OR
    
29.        expr?expr:expr
    
30.               conditional operator
    
31.        = *= /= %= += -= <<= >>= &= ^= |=
    
32.               assignment
    
33.        expr1 , expr2
    
34.               comma
    

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ly5066113

位运算符。
我给的是搜索论坛的结果，waker给的是man bash的内容。

我是DBA

明白了。哈