RHCE Scripting and Task Scheduling 3

Question 1

What `bash` option makes a script exit immediately if any command fails?

Accepted Answer

set -e

Answer

`set -e` (errexit) causes the script to exit immediately if any command returns a non-zero exit status.

Question 2

Which command lists pending `at` jobs?

Accepted Answer

Both A and B

Answer

Both `atq` and `at -l` list pending at jobs; `atq` is a traditional shorthand while `at -l` is the long form.

Question 3

What does `${#VAR}` return in a bash script?

Accepted Answer

Length of the string in VAR

Answer

`${#VAR}` is bash parameter expansion that returns the number of characters in the string value of VAR.

Question 4

Which `for` loop syntax in bash iterates over a list of numbers 1 through 5?

Accepted Answer

for i in {1..5}; do

Answer

Bash brace expansion `{1..5}` generates the sequence 1 2 3 4 5, which the `for` loop iterates over.

Question 5

What is the purpose of the `/etc/cron.deny` file?

Accepted Answer

Lists users who are NOT allowed to use crontab

Answer

Users listed in `/etc/cron.deny` are not permitted to create or modify crontab entries with the `crontab` command.

RHCE - Red Hat Certified Engineer Practice Test