Using a command declare for arithmetic

Whenever we declare any variable, by default, this variable stores the string type of data. We cannot do arithmetic operations on them. We can declare a variable as an integer by using the declare command. Such variables are declared as integers; if we try to assign a string to them, then bash assigns 0 in these variables.

Bash will report an error if we try to assign fractional values (floating points) to integer variables.

We can create an integer variable called value, shown as follows:

$ declare –i value

We tell the shell that the variable value is of type integer. Otherwise, shell treats all variables as character strings:

• If we try to assign the name string to the integer variable value, then the value variable will be assigned the 0 value by Bash shell:

  $ value=name
  $ echo $value
  0
  

• We need to enclose numbers between double quotes, otherwise we should not use space in arithmetic expressions:

  $ value=4 + 4
  bash: +: command not found
  

• When we remove...