LCA Shell Scripting & Automation 5

Question 1

Which bash option enables strict mode by catching unset variable references?

Accepted Answer

set -u

Answer

`set -u` (or `set -o nounset`) causes the shell to treat unset variables as an error and exit.

Question 2

What does `set -o pipefail` change about pipeline exit status?

Accepted Answer

The pipeline returns the exit status of the last failed command, not just the last command

Answer

Without `pipefail`, a pipeline's exit status is the last command's status; with it, any failure in the pipeline propagates.

Question 3

In bash, what is a here-document used for?

Accepted Answer

Providing multi-line input to a command inline in the script

Answer

A here-document (`<< DELIMITER ... DELIMITER`) feeds multiple lines of text directly as stdin to a command without needing a separate file.

Question 4

Which command schedules a one-time job to run at 3:00 AM tonight on a Linux system?

Accepted Answer

echo 'command' | at 03:00

Answer

The `at` command schedules one-time tasks; you pipe the command to `at` with a time argument.

Question 5

What is the correct way to source a file named `config.sh` in the current shell?

Accepted Answer

. config.sh

Answer

The dot (`.`) command or `source` built-in reads and executes commands from the file in the current shell environment.

(LCA) Certified Linux Administrator Practice Test