How to calculate the numbers in the Shell (bc/expr/$ (())/let/awk)

1.bc

Common calculation Tools , and supports floating-point arithmetic:

[Email protected] shell]# echo | Bc

2

floating point number accuracy problem not resolved

[Email protected] shell]# echo "1.2*1.2" | Bc

1.4

[Email protected] shell]# echo "scale=2;1.2*1.2" | Bc

1.44

[Email protected] shell]# echo "5.0/3.0" | Bc

1

[Email protected] shell]# echo "scale=2;5.0/6.0" |BC

.83

2.expr

floating-point arithmetic not supported, note operators have spaces around

[[email protected] shell]# Expr 10 + 10

20
[[email protected] shell]# expr 1500 + 900

[[email  Protected] shell]# expr 30/3

10
[[email protected] shell]# expr 30/3/2

5

[[email protected] shell]# Expr 30 \* 3

90

3.$ (())

with expr, floating-point arithmetic is not supported

[[email protected] shell]# echo $ ((+))

2

[[email protected] shell]# echo $ ((2*3))

6

[[email protected] shell]# echo $ ((6/2))

3

[[email protected] shell]# echo $ ((6/5))

1

4.let

Floating-point arithmetic is not supported, and direct output is not supported, only values can be assigned

[[email protected] shell]# let a=10+10

[Email protected] shell]# echo $a

20

[[email protected] shell]# let B=50/5

[Email protected] shell]# echo $b

10

[[email protected] shell]# let c=6*5

[Email protected] shell]# echo $c

30

[[email protected] shell]# let C=6/5

[Email protected] shell]# echo $c

1

5.awk

Common operations:

[[email protected] shell]# Echo|awk ' {print (+)} '

2

[[email protected] shell]# Echo|awk ' {print (1/2)} '

0.5

[[email protected] shell]# Echo|awk ' {print (1/3)} '

0.333333

[[email protected] shell]# Echo|awk ' {print (3*5)} '

15

Control Accuracy (printf) :

[Email protected] shell]# echo | awk ' {printf ("%.2f \ n", 1/2)} '

0.50

[Email protected] shell]# echo | awk ' {printf ("%.4f \ n", 1/3)} '

0.3333

Pass parameters:

[[email protected] shell]# echo | awk-v a=5-v b=6 ' {printf("%.4f \ n", A/b)} ' Note: The method a,b does not need to add the $ symbol

0.8333

[Email protected] shell]# a=5

[Email protected] shell]# b=6

[[email protected] shell]# Echo|awk "{print ($a/$b)}" Note: This method requires double quotation marks outside the curly braces

0.833333

This article is from the "Feng" blog, make sure to keep this source http://fengxiaoli.blog.51cto.com/12104465/1952187

How to calculate the numbers in the Shell (bc/expr/$ (())/let/awk)