Bash Basics

1. Print odd numbers from 1 to 100

2. Custom greetings

3. Read two numbers, and perform arithmetic op on them

Check whether the variables `x` and `y` contain valid integer values.

1. `[[ $x =~ ^[-+]?[0-9]+$ ]]`: This part checks if the variable `x` contains a valid integer. Let's break it down:

- `[[ ... ]]` is the conditional expression construct in Bash.

- `$x` is the variable being checked.

- `=~` is the operator used to match a regular expression.

- `^` matches the start of the string.

- `[-+]?` matches an optional plus or minus sign.

- `[0-9]+` matches one or more digits.

- `$` matches the end of the string. So, the entire regular expression matches a string that consists of an optional plus or minus sign followed by one or more digits.

2. `&&`: This is the logical AND operator. It means that both conditions must be true for the overall expression to evaluate to true.

3. `[[ $y =~ ^[-+]?[0-9]+$ ]]`: This part checks whether the variable `y` contains a valid integer in the same way as it did for `x`.

So, the code you provided checks if both `x` and `y` contain valid integers before performing any further operations. If both `x` and `y` are valid integers, the code following this condition can be executed.

4. Given two integers, x and y, identify whether x>y, x=y or x<y .