The arithmetic operation of Linux shell programming

+ Plus

-Minus

* Multiply

/except

* * Sub-party

% take-up

These operational symbols need to be escaped in some scenarios. For example, in a wildcard scenario

The operation must be two brackets or a bracket

Let operation does not display the result and requires a variable to hold the calculation result

Normal operation symbols are not good enough to make

If you do not want to use let, you can use two brackets or one bracket

Expr This command supports multiple operations

Spaces are required between each parameter

Let's practice.

1, select three users, three of the UID of the sum

2. Calculate the sum of the UID of 10th user and 20th user in/etc/passwd

3. Calculate the sum of the number of blank lines in the/etc/rc.d/init.d/functions and/etc/inittab files

The arithmetic operation of Linux shell programming