Declaring local variables in functions

Whenever we declare a variable in a script, it is accessible to all functions. The variable is global by default. If the variable is modified by any line of script or any function, it will be modified in global scope. This may create problems in certain situations. We will see this problem in the following script function_12.sh:

#!/bin/bash
name="John"
hello()
{name="Maya"
   echo $name
}
echo $name# name contains John
hello# name contains Maya
echo $name# name contains Maya

Test the script as follows:

$ chmod +x function_12.sh
$ ./function_12.sh

Output:

John
Maya
Maya

To make a variable local, we declare it as follows:

local var=value
local varName

Let's write the script function_13.sh as follows:

#!/bin/bash
name="John"
hello()
{local name="Mary"
echo $name
}
echo $name# name contains John
hello# name contains Mary
echo $name# name contains John

Test the script as follows:

$ chmod +x function_13.sh
$ ./function_13.sh

Output:

John
Mary
John

The command...