Bash Test Boolean - Shell-Bash

Bash Test Boolean is a feature in the Bash shell that allows you to test various conditions and return true/false values. This is especially useful when writing shell scripts that need to make decisions based on user input, environment variables, or other factors.

With Bash Test Boolean, you can test for the following conditions:

• File/directory exists
• File/directory is readable/writable/executable
• String/numeric comparisons
• Regular expressions

Here are some examples of Bash Test Boolean in action:

File/directory exists

if [ -e /path/to/file ]; then
  echo "File exists"
else
  echo "File does not exist"
fi

Markdown:

if [ -e /path/to/file ]; then echo "File exists" else echo "File does not exist" fi

File/directory is readable/writable/executable

if [ -r /path/to/file ]; then
  echo "File is readable"
else
  echo "File is not readable"
fi

Markdown:

if [ -r /path/to/file ]; then echo "File is readable" else echo "File is not readable" fi

## String/numeric comparisons

if [ "$var1" == "$var2" ]; then echo "Variables are equal" else echo "Variables are not equal" fi

if [ $num1 -gt $num2 ]; then echo "Number 1 is greater than Number 2" else echo "Number 2 is greater than Number 1" fi

Markdown:

```markdown

if [ "$var1" == "$var2" ]; then echo "Variables are equal" else echo "Variables are not equal" fi

if [ $num1 -gt $num2 ]; then echo "Number 1 is greater than Number 2" else echo "Number 2 is greater than Number 1" fi

## Regular expressions

if [[ "$var" =~ ^[A-Za-z]+$ ]]; then echo "Variable contains only letters" else echo "Variable contains other characters" fi

Markdown:

```markdown

if [[ "$var" =~ ^[A-Za-z]+$ ]]; then echo "Variable contains only letters" else echo "Variable contains other characters" fi

In conclusion, Bash Test Boolean is a powerful feature of the Bash shell that can help you write more complex and efficient shell scripts. By mastering these tests, you can create scripts that can make decisions based on a variety of factors, from user input to system environment variables.