Difference between single and double square brackets in Shell script

Single square brackets [ ] in a Shell script are used for basic conditional tests and are a synonym for the test command. Double square brackets [[ ]], on the other hand, are a more powerful version of the test command and are generally preferred in modern Shell scripting for enhanced functionality.

Some key differences between single and double square brackets include:

• Single square brackets require spaces around them, whereas double square brackets do not.
• Double square brackets allow for more complex conditional expressions and pattern matching than single square brackets.
• Using double square brackets is recommended for better readability and consistency in Shell scripts.

Overall, while both single and double square brackets can be used for conditional tests in Shell scripts, double square brackets offer more flexibility and functionality, making them a preferred choice for modern scripting practices.