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drills

Practice Linux troubleshooting with focused drills.

Two ways to practice: certification drills for LPIC-1, LFCS, and provisional Linux+ paths, plus troubleshooting drills for real Linux repair habits.

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Independent study support only. No affiliation, endorsement, exam dumps, or guaranteed exam results.

practice paths

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Troubleshooting drills

12 scenario drills for real Linux repair habits: inspect first, read the decisive field, and avoid broad fixes.

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Start here if

Pick the first drill by what you are trying to learn

Use the shortest route that matches the job in front of you, then widen into the full catalog after one focused drill.

You are learning LPIC-1 commands

Start with GNU and Unix command practice, then use drills that ask you to read output and explain the next safe command.

Open LPIC-1 command practice

You are practicing LFCS tasks

Start with storage, networking, or service-state drills where the first answer comes from terminal evidence.

Open LFCS storage practice

You are reviewing Linux+ style troubleshooting

Use the scenario drills first. They keep the work grounded in symptoms, safe commands, and common wrong moves.

Browse troubleshooting drills

practice method

Troubleshooting ladder

  1. Start safeUse a read-only command first, then explain the decisive output before changing anything.
  2. Read outputLook for the owner, service, file, mount, route, or status field that narrows the problem.
  3. Choose nextUse the next safe command from the drill or related cert practice page instead of jumping to a broad fix.
  4. Get helpUse command --help, man, apropos, type, and journalctl when the command or output is unfamiliar.

46 cert drills

Certification drills

Use these when you want LPIC-1, LFCS, or provisional Linux+ practice grouped by study path instead of by troubleshooting symptom.

12 troubleshooting drills

Troubleshooting drills

Drill library: these are scenario drills for real repair habits. Certification drills live above and in the focused cert drill index.

drill 3 commands LPIC-1 style filesystem practice

Disk Is Full: Prove Which Filesystem Is Out

A VPS starts returning write errors and an app cannot create new uploads. You need to decide whether the root filesystem, a mounted data volume, or inode exhaustion is the real problem before deleting anything.

3 related examples with output.

df -h && df -i
drill 4 commands LPIC-1 style GNU/Unix command practice

Find the Largest Files Under /var

The root filesystem is nearly full and /var looks suspicious. You need a read-only way to find the biggest files without crossing into other mounted filesystems.

2 related examples with output.

find /var -xdev -type f -printf '%s %p\n' | sort -nr | head -20
drill 3 commands LPIC-1 style essential services practice

Read Recent Logs for One Service

A service restarted during deploy and is now unhealthy. You need the recent unit logs, not every log line on the machine.

2 related examples with output.

journalctl -u nginx --since '30 minutes ago' --no-pager
drill 3 commands LFCS-style service troubleshooting drill

Check Whether Nginx Config Is Valid

A teammate changed a server block and wants to reload nginx. You need to prove the configuration parses before touching the running service.

2 related examples with output.

sudo nginx -t
drill 3 commands LPIC-1 style networking practice

Find Which Process Owns a Port

Port 8080 is already in use and a new service will not start. You need to identify the listener before killing or reconfiguring anything.

2 related examples with output.

sudo ss -ltnp 'sport = :8080'
drill 3 commands LPIC-1 style networking practice

Separate DNS Failure From Server Failure

Users say a site is down, but the server may still be answering. You need to compare public DNS with a forced request to the expected IP.

2 related examples with output.

dig +short example.com && curl -I https://example.com/
drill 3 commands LPIC-1 style permissions practice

Inspect Permissions Before chmod

An app cannot read a file and someone suggests chmod 777. You need to inspect the path, owner, group, and mode before changing permissions.

2 related examples with output.

namei -l /srv/app/current/.env
drill 3 commands LPIC-1 style file management practice

Preview What rsync --delete Would Remove

You need to mirror a release directory to a backup target, but stale files on the target should be removed. Before running the real sync, you must preview deletions.

2 related examples with output.

rsync -ani --delete /srv/app/releases/current/ /backup/app/current/
drill 3 commands LPIC-1 style essential services practice

List Failed systemd Units

After a reboot, a host is reachable but something feels broken. You need a quick inventory of failed units before digging into individual logs.

2 related examples with output.

systemctl --failed --no-pager
drill 3 commands LPIC-1 style package management practice

Check Pending Package Updates

A Debian or Ubuntu server may be missing important updates. You need to list pending upgrades without installing anything.

2 related examples with output.

apt list --upgradable
drill 3 commands LPIC-1 style process inspection practice

Check Memory Pressure Before Restarting

A server is slow and someone wants to restart the app. You need to see whether RAM, swap, or a specific process is the likely cause.

2 related examples with output.

free -h && ps aux --sort=-%mem | head
drill 3 commands LPIC-1 style security practice

Review Failed SSH Logins

A public VPS has SSH exposed and you need to see whether failed login attempts are normal background noise or focused guessing against real usernames.

2 related examples with output.

journalctl -u ssh --since today --no-pager | grep 'Failed password'