Linux Shell Scripting 5

Question 1

What does `set -u` do in a bash script?

Accepted Answer

Treats unset variables as an error when they are expanded

Answer

`set -u` causes the script to exit with an error if an unset variable is referenced, catching typos early.

Question 2

How do you append a line to a file inside a shell script without overwriting it?

Accepted Answer

echo 'line' >> file

Answer

`>>` appends to a file; `>` truncates and overwrites.

Question 3

What is the output of `echo $((3 ** 2))` in bash?

Accepted Answer

9

Answer

`**` is the exponentiation operator in bash arithmetic; `3 ** 2` equals 9.

Question 4

Which syntax correctly declares an indexed array in bash?

Accepted Answer

arr=(one two three)

Answer

In bash, `arr=(value1 value2 ...)` initializes an indexed array with space-separated values.

Question 5

What does `${arr[@]}` expand to when `arr` is a bash array?

Accepted Answer

All array elements as separate words

Answer

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

Linux Practice Test