Day 4 - Secondary Practical Exam Mock: Short-Answer and Hands-On Drills

📌 Key Points

• For Level 1, you must pass the secondary practical exam after passing the primary written exam to get the final pass. The secondary exam has short-answer and hands-on tasks that you must write out yourself.
• Unlike the written exam, where you "choose," this is an exam where you "write," so exact spelling and options are your score. Practice in multiple-choice form, but you also need to drill writing by hand.
• The hands-on tasks revolve around 6 areas — accounts and permissions, text processing, disks and mounting, scheduling, network and service configuration, systemctl.
• The distinction between "now" and "permanent" is the number one cause of lost points — mount vs /etc/fstab, start vs enable, firewall-cmd without --permanent.
• For permission calculation, rwx=7, rw-=6, r-x=5, r--=4, and the special permissions (SetUID 4, SetGID 2, Sticky 1) are added as the leading digit.
• The space before the parenthesis in /etc/exports and the spaces around = in shell variable assignment are classic point-losing traps on the practical exam.

Hands-On Key 1: User and Permission Management Commands

• Get the account and permission commands tested in the practical exam into your fingers.

Practical exam points: Get useradd's -m (create home), -s (specify shell), -G (supplementary group), and -u (UID) exactly right. The -r in userdel -r deletes the home directory and mail spool too.

Hands-On Key 2: File Search and Text Processing

• find, grep, awk, and sed are the core tools of the practical hands-on tasks.

find options in focus: -name (name), -type f/d (file/directory), -mtime +7 (modified more than 7 days ago), -size +100M (size), -perm (permissions), -exec ... {} \; (execute). On the practical exam, you use the -exec rm {} \; form.

Hands-On Key 3: Disk and Mount Scenarios

• The whole flow of adding a disk → partition → format → mount → register in fstab is asked.

fdisk /dev/sdb        # create a partition
mkfs.ext4 /dev/sdb1   # create a filesystem
mkdir /data           # mount point
mount /dev/sdb1 /data # temporary mount
# register permanently in /etc/fstab:
# /dev/sdb1  /data  ext4  defaults  0  0

⚠️ Practical exam trap: A temporary mount (mount) disappears on reboot. For a permanent mount, you must register it in /etc/fstab. You must write the 6 fstab fields (device, mount point, type, options, dump, fsck order) exactly to avoid losing points.

Hands-On Key 4: Processes and Job Scheduling

• This covers cron, at, and process control.

• cron field example: 0 3 * * 1 /backup.sh = runs every Monday at 03:00.

cron field order: minute (0-59) hour (0-23) day (1-31) month (1-12) weekday (0-7, 0 and 7 = Sunday). * means every time, */10 means every 10 units, 1-5 is a range, and 1,15 is a list.

Hands-On Key 5: Network and Service Configuration Scenarios

• You are made to write the key entries of service configuration files yourself.

Firewall on the practical exam: To open a port permanently, run firewall-cmd --permanent --add-port=80/tcp and then firewall-cmd --reload. Without --permanent, it disappears on reboot.

Hands-On Key 6: Service Management (systemctl)

• The systemd service control commands are essential for the practical exam.

⚠️ enable vs start: start starts it now, and enable starts it automatically at boot. They are separate, so if you need both, use systemctl enable --now service.

Hands-On Key 7: Log Analysis Scenarios

• Reading logs and finding the cause when diagnosing a failure also appears on the practical exam.

• For real-time monitoring, use tail -f /var/log/messages; to extract a specific pattern, use grep "Failed" /var/log/secure.

journalctl on the practical exam: In a systemd environment, you also use journalctl -u service-name (logs for a specific service), journalctl -b (this boot), and journalctl -f (real-time).

Hands-On Key 8: Shell Scripting Basics

• Writing and interpreting simple scripts can come up as a hands-on task.

Test operators: -f (file exists), -d (directory), -z (empty string), -eq/-ne/-lt/-gt (numeric comparison). Spaces on both sides inside [ ] are mandatory.

Variable assignment trap: Putting spaces around =, as in VAR = value, causes an error. Always write it joined, as VAR=value. Reference it with $VAR or ${VAR}.

Hands-On Key 9: Permission Scenarios Roundup

• Compound permission problems require you to calculate the chmod numbers yourself.

Calculation in one line: rwx=7, rw-=6, r-x=5, r--=4. Special permissions are added as the leading digit of the 4 digits (SetUID 4, SetGID 2, Sticky 1). The permission of /tmp is 1777 (Sticky+777).

Hands-On Key 10: Writing Service Configuration Files Directly

• On the practical exam, you are made to fill in specific lines of a configuration file yourself.
• Get the short snippets into your fingers.
• NFS share (/etc/exports)

/srv/share  192.168.1.0/24(rw,sync,no_subtree_check)

• Samba share (/etc/samba/smb.conf)

[data]
   path = /srv/data
   writable = yes
   valid users = @staff

• cron registration (crontab -e)

30 2 * * * /usr/local/bin/backup.sh

The exports whitespace trap: You must not put a space between client(options). If you separate them as in 192.168.1.0/24 (rw), rw is opened to all hosts. The number one point-loser on the practical exam.

Hands-On Key 11: Command Combinations and Pipes

• Hands-on tasks often require pipe and redirection combinations rather than a single command.

• Example: ps -ef | grep nginx | grep -v grep | awk '{print $2}' — extracts only nginx's PID.

Combination examples: du -sh * | sort -rh | head (largest first), cat access.log | grep 404 | wc -l (count of 404s). The mindset of chaining filters with pipes is the core of the practical exam.

Hands-On Key 12: Boot and Recovery Scenarios

• Failure recovery is a high-difficulty hands-on task. Let's summarize the key situations.

Single-user mode: If you enter by adding single or rd.break to the kernel line in the GRUB menu, you can do recovery work with root privileges. This is the standard procedure for password recovery.

You need to practice spelling and options repeatedly by hand. Check yourself with the mock exam below.

📖 Glossary

• Short-answer / hands-on : A type where you write out a command, option, or path briefly / a type where you work through a scenario as a command procedure.
• useradd -m -s : The option combination that creates an account by making a home directory (-m) and specifying a login shell (-s).
• userdel -r : An option that deletes the home directory and mailbox along with the account.
• -exec {} \; : The syntax by which find runs a command for each file found. {} stands in for the file name.
• Permanent mount : A mount registered in /etc/fstab that persists after reboot. If you only run mount, it is temporary.
• fstab 6 fields : device, mount point, type, options, dump, fsck order.
• enable vs start : Register to start automatically at boot / start immediately now. If you need both, use enable --now.
• --permanent + --reload : The two steps that save a firewalld setting permanently and apply it to the current session.
• journalctl : The command for viewing the logs that systemd collects. -u (service), -b (this boot), -f (real-time).
• Special permission digit : The leading digit of the four chmod digits. You add SetUID 4, SetGID 2, and Sticky 1 (/tmp is 1777).
• exports whitespace trap : An NFS syntax trap in which separating the client and the parenthesis opens permissions to all hosts.
• Pipe (|) : A connection that passes the previous command's output as the next command's input. The mindset of chaining filters is the core of the practical exam.
• Single-user mode : A recovery mode entered from GRUB with single or rd.break. It is the standard procedure for resetting the root password.

📝 Practice Questions

Click a choice to reveal the answer and explanation.

Question 1

Which command correctly creates the user 'kim' with a home directory and sets the login shell to bash?

• Auseradd kim
• Buseradd -m -s /bin/bash kim
• Cusermod -m kim
• Dadduser -s kim

Question 2

Which command recursively searches for the string "error" under /var/log with line numbers?

• Agrep error /var/log
• Bgrep -rn "error" /var/log
• Cfind /var/log -name error
• Dawk '/error/' /var/log

Question 3

Which file must you register the added disk partition /dev/sdb1 in so that it is automatically mounted at /data even after a reboot?

• A/etc/mtab
• B/etc/fstab
• C/etc/exports
• D/proc/mounts

Question 4

Which crontab entry runs /backup.sh every Monday at 3 AM?

• A0 3 * * 1 /backup.sh
• B3 0 1 * * /backup.sh
• C* * 1 3 0 /backup.sh
• D0 3 1 * * /backup.sh

Question 5

Which is the correct procedure for permanently opening port 80/tcp in firewalld so that it persists after reboot?

• ARun only firewall-cmd --add-port=80/tcp
• Bfirewall-cmd --permanent --add-port=80/tcp followed by firewall-cmd --reload
• Ciptables -A INPUT -p tcp --dport 80
• DRun only systemctl restart firewalld

Question 6

Which command starts the httpd service now and also sets it to run automatically at boot, all at once?

• Asystemctl start httpd
• Bsystemctl enable httpd
• Csystemctl enable --now httpd
• Dsystemctl reload httpd

Question 7

Which command uses find to locate and delete files under /tmp that have not been modified for more than 7 days?

• Afind /tmp -mtime 7 -delete
• Bfind /tmp -mtime +7 -exec rm {} \;
• Cfind /tmp -atime -7 -rm
• Drm -rf /tmp/*7*

Question 8

Which sed command replaces every "old" with "new" in a text file and prints the result?

• Ased 's/old/new/' file
• Bsed 's/old/new/g' file
• Csed 'old/new' file
• Dawk 's/old/new/g' file

Question 9

Which command terminates all running 'nginx' processes at once by name?

• Akill nginx
• Bkill -9 nginx
• Ckillall nginx
• Dpkill -l nginx

Question 10

Which command correctly adds the SetUID permission to the file report.sh?

• Achmod u+s report.sh
• Bchmod o+t report.sh
• Cchmod g+s report.sh
• Dchown +s report.sh