Shell Scripting & Automation Flashcards

Which operator is used for arithmetic expansion in bash?

Answer: $(( ))

The `$(( ))` syntax performs arithmetic expansion and is the preferred POSIX-compatible method.

How do you redirect both stdout and stderr to the same file in bash?

Answer: command &> file

`&>` is bash shorthand for redirecting both stdout (fd 1) and stderr (fd 2) to the same destination.

What does `command -v ls` return when `ls` is found in PATH?

Answer: The full path or alias of ls

`command -v` prints the resolved path or alias for a command, making it useful for checking if a command exists.

In a bash script, which syntax correctly passes an array as individual arguments to a function?

Answer: func "${arr[@]}"

`"${arr[@]}"` expands each array element as a separate quoted word, preserving elements with spaces.

What is the purpose of `exec 3>&1` in a bash script?

Answer: Saves the current stdout to file descriptor 3

`exec 3>&1` duplicates stdout to fd 3, allowing you to save and later restore the original stdout.

Which construct in bash is used to perform pattern matching in a case statement?

Answer: case $VAR in pattern) ... ;; esac

The `case ... esac` construct uses glob patterns to match values and execute corresponding code blocks.

What does the `local` keyword do inside a bash function?

Answer: Declares a variable scoped to the function

`local` creates a variable whose scope is limited to the enclosing function and its children.