Shell Basics 03 Mathematical operations

There are some limitations to mathematical operations in the shell. It is mainly divided into the following types:

1. square brackets-------support only integer arithmetic

[[email protected] documents]$ var1=$[1+5]

[email protected] documents]$ echo $var 1

6
[Email protected] documents]$ var2=$[$var 1*2]
[Email protected] documents]$ echo $var 2
12
[Email protected] documents]$ var1=100
[Email protected] documents]$ var2=45
[[email protected] documents]$ var3=$[$var 1/$var 2]
[Email protected] documents]$ echo $var 3
2

2. Floating point Solution

Use the built-in bash calculator directly, called BC. It supports multiple types of calculations

Floating-point computing is designed to be a problem of precision, and you can set the value of the variable scale to fit the precision we want. For example, scale=4, meaning that 4-bit output is retained after the decimal point

BC can handle other data types, time reference.

Reference Documents :

Linux command line and Shell Scripting Encyclopedia (3rd edition) [Mei] Bloom (Richard Blum), Bresnahan (Christine Bresnahan), Jia, Wuhai

Shell Basics 03 Mathematical operations