Assess your ability to identify and resolve typical Linux problems using the essential tools and concepts within the Linux ecosystem. This quiz covers command-line utilities, diagnostic strategies, permission management, system monitoring, and log interpretation vital for Linux troubleshooting.
When a Linux application fails to start and displays 'Permission denied', which tool or command is most useful for immediately identifying problematic file permissions in the current directory?
Explanation: The ls -l command displays file and directory permissions, making it ideal for quickly finding permission issues. ps aux lists running processes but does not show file permissions. df -h displays disk space, which isn't directly related to permissions. du -sh is used for disk usage summaries and is also unrelated to permission diagnostics.
If you are unable to connect to a remote server and suspect a network issue, which command would best help you determine if there is packet loss along the route?
Explanation: traceroute helps you map the path your packets take to the remote server and can reveal where loss or delays occur. whoami simply returns the current user name. free displays memory usage statistics, which aren't relevant to network issues. chmod is used to change file permissions but does not assist in network diagnostics.
A user's Linux system becomes slow, and it's suspected that a process is consuming excessive CPU resources. Which command would best display a live, sorted list of processes using the most CPU?
Explanation: The top command provides a dynamic, real-time view of running processes and their CPU usage. ln creates links between files, pwd prints the current working directory, and cp copies files, none of which help with monitoring CPU usage.
You notice repeated authentication failures when users try to log in. Which file should you check for detailed records of these incidents on a standard Linux system?
Explanation: /var/log/auth.log stores authentication-related events and is the best source for investigating login issues. /etc/shadow contains hashed passwords but does not record events. /home/user/.bashrc is a user script for shell customization. /etc/hosts maps hostnames to IPs but is unrelated to authentication logs.
When a Linux system reports 'No space left on device', which of the following commands provides a human-readable summary of available disk space on all mounted filesystems?
Explanation: The df -h command summarizes disk space usage and availability with easy-to-read units, making it straightforward to identify full partitions. grep -i searches for patterns in text, not disk space. lsb_release -a shows distribution information, and ps -ef lists processes; neither is useful for checking available disk space.