Backup strategies in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this incremental backup command?

Consider the following command that creates an incremental backup using rsync. What will be the output message shown after running it?

Linux CLI

rsync -av --link-dest=/backup/full /home/user/ /backup/incremental

A

sending incremental file list
error: link-dest directory not found

B

sending incremental file list
backup completed successfully

C

sending incremental file list
created directory /backup/incremental
file1
file2

D rsync: command not found

💡 Hint

Think about what --link-dest does and what rsync outputs when it runs successfully.

The --link-dest option tells rsync to hard link unchanged files from the specified directory. Rsync outputs the list of files it processes and directories it creates. Option C matches the expected output.

🧠 Conceptual

intermediate

Which backup strategy minimizes storage by saving only changed data?

Among these backup strategies, which one saves storage space by only storing changes since the last backup?

A Incremental backup

B Differential backup

C Full backup

D Mirror backup

💡 Hint

Think about which backup type saves only the changes since the last backup, not the entire data.

Incremental backups save only the data changed since the last backup, minimizing storage use compared to full or differential backups.

🔧 Debug

advanced

Why does this backup script fail to create a compressed archive?

This script is intended to create a compressed tar archive of /var/log but fails with an error. What is the cause?

#!/bin/bash
backup_dir=/backup
filename=logs_backup.tar.gz
tar -czvf $backup_dir/$filename /var/log

A The variable filename is not quoted, causing word splitting.

B The tar command is missing the -f option to specify the filename.

C The script lacks execute permission, so it cannot run.

D The backup directory /backup does not exist, so tar cannot write the archive.

💡 Hint

Check if the directory where the archive is saved exists.

If /backup does not exist, tar cannot create the archive file there, causing an error. The script does use -f correctly and variables are expanded properly.

🚀 Application

advanced

Which command creates a daily rotating backup with 7 days retention using rsnapshot?

You want to configure rsnapshot to keep daily backups and automatically rotate them, keeping backups for 7 days. Which command below correctly triggers this behavior?

A rsnapshot -c /etc/rsnapshot.conf daily

B rsnapshot -t daily

C rsnapshot -r 7 daily

D rsnapshot daily

💡 Hint

The configuration file controls retention and intervals; the command triggers the snapshot.

Option A runs rsnapshot with the specified config file and the 'daily' interval, which is configured to keep 7 days of backups. Other options are invalid or incomplete.

📝 Syntax

expert

What error does this backup script produce and why?

Analyze this bash script snippet intended to copy files and create a log. What error will it produce?

#!/bin/bash
backup_src="/home/user/data"
backup_dest="/mnt/backup"
cp -r $backup_src $backup_dest > backup.log 2>&1 &
wait $!
echo "Backup completed" >> backup.log

A No error; the script runs and logs output correctly.

B wait: no child processes; because the background job finished before wait.

C cp: missing destination file operand after /mnt/backup; due to missing trailing slash.

D Syntax error: unexpected token near '&'

💡 Hint

Consider how the shell handles background jobs and the wait command.

The cp command runs in background and may finish before wait is called, causing 'wait: no child processes' error. The script syntax is correct and cp command is valid.