[Shell Foundation]--arithmetic operations

The shell supports only integer operations. Typically let, expr, declare, $[] are implemented.

More accurate calculations suggest using the BC tools under Linux-a high-precision computing language.

1. let is a shell built-in integer operation command

# # can be completed +-*/% * * Subtraction Yu Yu and other general operatorsLet a=1+1;Echo$alet b=9/4;Echo$blet C=Ten%3;Echo$clet D=a**3;Echo$d
# # = = = *=/=%= and other mixed operators can be completed
X=8; let x-=2 Echo$xy=8; let y/=2 Echo$y # Bash let.SH2218

# # Shift Operation
n=4Echo "obase=2; $n"|BC #输出一个数的二进制let"val1= $n <<2"Echo "obase=2; $val 1"| BC;Echo$val 1let"val2= $n >>2"Echo "obase=2; $val 2"| bcEcho$val a bash let.SH -10000 -11

# #按位与, bitwise OR, bitwise NON, bitwise XOR, or arithmetic
n1=8N2=4Echo-N"N1:";Echo "obase=2; $n 1"|BCEcho-N"N2:";Echo "obase=2; $n 2"|Bclet"value= $n 1| $n 2"Echo-N"| or operation:";Echo "obase=2; $value"|Bclet"value= $n 1& $n 2"Echo-N"& and Operations:";Echo "obase=2; $value"|Bclet"value= $n 1^ $n 2"Echo-N"^ xor operation:";Echo "obase=2; $value"|bc# bash let.SHN1: +N2: -| or operation:1100& and Operations:0^ XOR Operation:1100

# # self-increment self-subtraction operation
n1=TenN2=Ten Let"result_1= (++N1)"#先自增再赋值 #注意此时里面的n1并没有写成 $n 1
 Let"result_2= (n2++)"#先赋值再自增Echo  "n1= $n 1"Echo  "n2= $n 2"Echo  "result_1= $result _1"Echo  "result_2= $result _2"#bash let.SH One One OneTen

2. Other operators $[], expr, declare

Echo$[1+1]Echo$[5/2]Echo$[2**3]Expr 2\*2 #注意操作数运算符的空格; and the escape of the operatorDeclare-I JJ=1+1Echo$J #bash test.SH22842

3. Arithmetic Expression $ ((arithmetic expression))

i=2echo $ ((2*i+1))Echo $ ((2* (i+1))  #可以用括号表达先计算括号里的式子 #bash test. SH 5 6

4. BC Tools (more commonly used)

Echo " 3^2 " | BC   #注意怎么写 echo"scale=3;10/3" | BC  #scale =n means to reserve N as decimal #bash test. SH 9 3.333

[Shell Foundation]--arithmetic operations