Prepare for the LFCS certification

The LFCS validates Linux administration skills that are agnostic to any particular distribution. It covers essential commands (Git, services, performance, SSL), operations and deployment (packages, recovery, libvirt, containers, SELinux), users and groups (profiles, limits, ACL, LDAP), storage (LVM, NFS, autofs) and networking (OpenSSH, firewall, NAT, reverse proxy), in 2 hours, on a real Linux terminal.

This page is the LFCS preparation hub. It follows the 5 official domains of the blueprint and points you to the guides and labs to work on for each one.

How to use this hub

The hub is read in the order of the four steps below: understand the exam, measure your gaps, go deeper into each objective, then face the labs.

1. Read the format and the rules of the day, to know exactly what to expect.
2. Go through the 5 official domains, to identify your strengths and gaps.
3. Work through the Essential skills page, to understand what each objective involves in practice.
4. Move on to the companion repository labs, to validate your skills in conditions close to the exam.

What you will learn

• The format and real conditions of the LFCS exam
• The 5 official domains and their respective weight
• What each domain covers in practice, beyond the official titles
• A preparation plan in 6 blocks, from the foundation to advanced skills
• The technical traps to know before the day

What the LFCS validates

The LFCS certifies your ability to administer a Linux system in real conditions, without being tied to a particular distribution. The skills assessed cover a wide spectrum:

• Cross-cutting essential commands: Git, creating and troubleshooting services, performance monitoring, application constraints, disk space, SSL/TLS certificates
• Operations and deployment: kernel parameters, process and service diagnosis, scheduling, package and repository management, recovery after failure, libvirt VMs, container engines, SELinux
• Users and groups: local accounts, personal and system-wide environment profiles, resource limits, ACL, LDAP accounts
• Storage: LVM, virtual file systems, remote file systems (NFS, iSCSI), autofs, swap, storage performance
• Networking: IPv4/IPv6 addressing, DNS resolution, NTP synchronisation, network monitoring, OpenSSH server/client, filtering/NAT/port redirection, static routing, bridge and bonding, reverse proxy and load balancer

The LFCS is vendor-neutral

Since 11 May 2023, the Linux Foundation has removed distribution selection from the exam. The LFCS assesses cross-cutting Linux skills, independent of any distribution family. If your professional environment is RHEL-centred, the RHCSA will be more directly useful, but the two certifications complement each other.

Exam format

Aspect	Value
Duration	2 hours
Type	Proctored hands-on exam (performance-based)
Number of tasks	17 to 20 tasks
Minimum score	67%
Mode	Online, remote proctoring through PSI Bridge
Certification validity	2 years
Exam window	12 months after purchase
Attempts	1 attempt + 1 retake included if you fail
Price	$445, exam only (checked on 2026-10-01)
Killer.sh simulator	2 sessions included, 36 h of access each, 20 scenarios
Languages	English; other languages on offer are checked on the official page at purchase time
Allowed resources	man, documentation installed by the distribution (/usr/share), distribution packages installable if needed

Swipe to see more

The point of this table most often badly anticipated is the allowed resources row. The official Linux Foundation instructions phrase it negatively: "resources that cannot be accessed from within the terminal are not allowed". In other words, no browser tab, no online documentation, no personal wiki. You have the manual pages, what the distribution installed under /usr/share, and the option to install a distribution package if its documentation is missing. A candidate used to searching the web loses much more time than expected on the day, and that is reason enough to practise with man open and the browser closed.

The Killer.sh simulator, used well

The included simulator contains 20 scenarios, the same for both sessions (killer.sh FAQ). Each session stays open for 36 hours from its activation, and the working session itself lasts 120 minutes, after which the solutions are shown. It is mainly used to get familiar with the interface, the remote desktop and the style of the tasks, not to predict the real exam. Use your two sessions to note the conventions of the environment.

The price, the validity period and the exam conditions were checked on 2026-10-01 and may change without notice. The official page is the reference: training.linuxfoundation.org/certification/lfcs.

The 5 official domains of the blueprint

How to read the table

The "Official objective summary" column rephrases the terms of the Linux Foundation blueprint. The "What it covers" column is a teaching interpretation: it describes the concrete skills expected, without imposing specific tools.

Domain	Weight	Official objective summary	What it covers
Operations and deployment	25%	Kernel parameters, processes and services, scheduled jobs, software packages and repositories, recovery from failures, VMs (libvirt), container engines, SELinux	Persistent and non-persistent kernel parameters, process and service diagnosis, scheduling, package and repository management, recovery from hardware or system failure, libvirt virtual machines, container engines, mandatory access control
Networking	25%	IPv4/IPv6, hostname resolution, NTP, OpenSSH, packet filtering, NAT, static routing, bridge, bonding, reverse proxies	Addressing, DNS resolution, time synchronisation, SSH server/client, firewall, NAT, routing, bridge/bonding, reverse proxy
Storage	20%	LVM, partitions, filesystems, NFS/CIFS/iSCSI, swap, autofs, storage performance	Partitions, LVM, persistent mounts, remote file systems, dynamic mounting, swap, I/O performance
Essential commands	20%	Basic Git operations, services, performance, constraints, diskspace, SSL certificates	Git versioning, service creation, system monitoring, application constraints, disk space, SSL/TLS certificates
Users and groups	10%	Local user and group accounts, personal and system-wide environment profiles, user resource limits, ACLs, LDAP user and group accounts	Accounts and groups, personal and system shell profiles, resource limits, ACL, LDAP integration

Swipe to see more

Networking and operations make the difference

With 50% of the blueprint, networking and system operations are the most heavily weighted domains. A candidate who neglects network configuration or service diagnosis takes a major risk.

What you must be able to do without hesitation

For each official objective, examples of tools are given; they are not a list imposed by the blueprint.

Essential commands

Official objective: Basic Git Operations, services creation and troubleshooting, monitoring system performance, determining application and service constraints, managing disk usage, working with SSL certificates

• Git: initialise a repository, clone, create a branch, commit, merge, push
• Create and troubleshoot a service: write a systemd unit file, diagnose a failed service
• Monitor performance: identify CPU, memory and I/O bottlenecks
• Application constraints: resource limits, kernel parameters
• Disk space: analyse real usage, identify deleted files still open
• SSL/TLS certificates: generate, inspect, verify certificates

Operations and deployment

Official objective: Configure kernel parameters (persistent and non-persistent), diagnose/identify/manage/troubleshoot processes and services, manage or schedule jobs, search for/install/validate/maintain software packages or repositories, recover from hardware/OS/filesystem failures, manage Virtual Machines (libvirt), configure container engines, create and enforce MAC using SELinux

• Kernel parameters: read and change a value live, make it persistent, check that it survives a reboot
• Processes and services: identify a process that consumes, diagnose a failed service, act without rebooting the machine
• Scheduling: configure recurring tasks (cron or systemd timers)
• Packages and repositories: search, install, check the origin of a package, add a repository, manage versions
• Recovery: get back from a system that no longer boots, a wrong /etc/fstab or a file system in error
• libvirt VMs: list, start, stop, create virtual machines
• Containers: start, inspect, generate a system service; the tool depends on the distribution
• SELinux: manage enforcing mode, fix contexts, enable booleans, allow ports

Users and groups

Official objective: Create and manage local user and group accounts, manage personal and system-wide environment profiles, configure user resource limits, configure and manage ACLs, configure the system to use LDAP user and group accounts

• Accounts and policies: create users, manage expiry, shells and passwords
• Environment profiles: configure the environment at system and user level
• Resource limits: set constraints per user or group
• ACL: apply finer permissions than ugo/rwx
• LDAP: integrate a centralised identity source

sudo delegation and SSH key authentication do not appear in this domain. sudo is not a named objective of the blueprint, and OpenSSH belongs to the Networking domain. Both remain essential in practice, and the site teaches them: they simply do not count in this domain's 10%.

Storage

Official objective: LVM, partitions, filesystems, remote filesystems and network block devices, swap, autofs, storage performance

• Partitions + formatting: create and format partitions
• LVM: create, extend, format and mount logical volumes
• Persistent mount through /etc/fstab with UUID
• Remote file systems: NFS, CIFS, iSCSI
• autofs: dynamic on-demand mounting
• Swap: create and enable a swap space
• Storage performance: measure and diagnose I/O performance

Networking

Official objective: IPv4/IPv6, hostname resolution, NTP, OpenSSH, packet filtering/NAT, static routing, bridge/bonding, reverse proxies/load balancers

1. Addressing + resolution: configure IPv4/IPv6 addresses and hostname resolution
2. NTP synchronisation: configure and check time synchronisation
3. Network monitoring: diagnose connectivity and open ports
4. OpenSSH server and client: configure key authentication, harden the server
5. Filtering, NAT, port redirection: define persistent rules
6. Static routing: add persistent routes
7. Bridge and bonding: create an aggregated interface or a network bridge
8. Reverse proxy and load balancer: configure a front-end service to distribute traffic to backends

Prerequisites before you start

1. Master the Linux terminal

   Navigate the file system, create directories, copy, move and delete files without hesitation. It is the implicit foundation of the whole blueprint.

2. Understand Unix permissions

   Read rwxr-xr-x, use chmod in octal and symbolic notation, know chown and chgrp.

3. Have used systemctl

   Be comfortable with start, stop, enable, disable, status. If not, start with the services and systemd guides.

4. Have practised on a real VM or a real server

   The LFCS is a hands-on exam. Set up a KVM lab or a VM; working only in a browser or on Windows WSL is not enough.

Preparation plan

Structure of the plan

The 6 blocks below follow the 5 official domains of the blueprint, with a block 0 of prerequisites. For each block: the official objective is stated, then the practical translation and the recommended guides and labs. The progression follows a teaching order, from the foundation to the advanced skills.

Block 0, Prerequisites

Linux foundation before the certification

This block is not part of the official blueprint

The Linux Foundation imposes no formal prerequisite to take the LFCS. This block 0 is a teaching structure proposed by this site: the skills below are assumed by the blueprint and no longer assessed directly, but without them, no official domain can be tackled.

What you must already master:

• Navigating the file system (ls, cd, find, locate)
• Handling files and text (cp, mv, rm, cat, grep, awk, sed)
• Unix permissions (chmod, chown, umask, SUID/SGID/sticky bit)
• The vi/vim editor, essential to edit files in an exam situation
• Understanding the Linux file system hierarchy (FHS)

Site guides:

The essential skills page goes over navigation, file handling and text filtering. The Linux permissions guide covers chmod, chown, umask and the SUID and SGID bits, and the vim editor guide its modes, navigation and search, enough to edit a file without hesitation on the day.

Block 1, Essential commands

Git, services, performance, SSL/TLS

Official objective (LFCS domain): Basic Git Operations. Create, configure, and troubleshoot services. Monitor and troubleshoot system performance and services. Determine application and service specific constraints. Troubleshoot diskspace issues. Work with SSL certificates.

This domain changed on 11 May 2023

The "Essential Commands" domain no longer covers navigation or basic permissions, which are implicit prerequisites. It now covers cross-cutting skills: Git, service management, performance monitoring, application constraints, disk space and SSL/TLS certificates.

What it means in practice:

• Use Git for versioning: init, clone, add, commit, log, diff, branch, switch, merge, stash, remote, push, pull
• Create and troubleshoot a systemd service: write a unit file, systemctl daemon-reload, diagnose a failed
• Monitor performance: top, vmstat, iostat, free, uptime, sar (examples of tools, not an exhaustive list)
• Application constraints: ulimit -a, /etc/security/limits.conf, sysctl, lsof
• Disk space: df -h, du -sh, lsof +L1 (deleted files still open), find -size
• SSL/TLS: openssl req, openssl x509, openssl s_client, openssl verify

Companion repository labs:

dsoxlab list-labs --level lfcs --bloc 1

Site guides:

For Git, the Git course (in French) covers the command-line basics. systemctl day to day teaches you to start, enable and troubleshoot a service, unit files included. Process management and checking system load cover performance: top, vmstat, iostat, sar, /proc/pressure and the OOM killer. Check disk space and inodes handles df, du, find -size and lsof +L1, the command that finds a deleted file still open.

For SSL/TLS certificates, the guide TLS diagnosis: debug SSL errors with openssl (in French) trains you to inspect a certificate with openssl s_client and openssl x509, to read a chain of trust and to diagnose common errors. For the other half of the objective, creating certificates, the guide Generate TLS certificates with openssl (in French) covers the private key, the CSR, the self-signed certificate, an internal CA and its installation in the trust store.

Block 2, Operations

Kernel, processes, packages, recovery, libvirt, containers, SELinux

Official objective (LFCS domain): Configure kernel parameters, persistent and non-persistent. Diagnose, identify, manage, and troubleshoot processes and services. Manage or schedule jobs for executing commands. Search for, install, validate, and maintain software packages or repositories. Recover from hardware, operating system, or filesystem failures. Manage Virtual Machines (libvirt). Configure container engines, create and manage containers. Create and enforce MAC using SELinux.

What it means in practice:

• Kernel parameters: sysctl and /etc/sysctl.d/ for persistence
• Processes: ps, top, kill, nice, renice, jobs, bg, fg, nohup
• systemd targets: identify, change the default target (systemctl set-default), reach rescue mode through GRUB2
• Scheduling: cron, systemd timers
• Packages and repositories: search, install, check and maintain, with the package manager of the distribution you meet on the day
• Recovery: get back from a stuck boot, a wrong /etc/fstab, a file system gone read-only
• libvirt VMs: virsh list, start, shutdown, define, autostart
• Containers: start, inspect, generate a system service; the tool depends on the distro (examples: podman, nerdctl)
• SELinux: getenforce, setenforce, chcon, restorecon, semanage fcontext, setsebool -P, semanage port, ausearch, sealert

Three objectives long missing from this page

Package and repository management, recovery after failure and persistent kernel parameters are official objectives of this domain, just like containers. They were missing from this page's plan until 2026-09-15, although the site has taught them for a long time. No page was created to fill the gap: the guides existed, it was the mapping that was wrong.

Companion repository labs:

dsoxlab list-labs --level lfcs --bloc 2

Site guides:

Processes and systemd: process management (ps, kill, nice, jobs) and the systemd architecture (targets, boot, dependencies). Scheduling: cron, at for a single run, and systemd timers with OnCalendar and their persistence. Scripts, to automate these tasks: write a shell script, conditionals and tests, loops and robust scripts with set -euo pipefail and trap.

Logs: journalctl to filter by unit or by level, and logrotate for rotation and purging. Packages and repositories: the package manager module (apt, dnf, zypper, pacman, apk) and understand packages for repositories and signatures. Recovery: a server stuck at boot, between a wrong fstab and rescue mode, and a read-only file system, with the fsck verdict. Kernel: boot parameters, on the kernel command line and in GRUB.

For mandatory access control, the guide SELinux: understand, troubleshoot and disable covers modes, contexts, booleans and the diagnosis of AVC denials. On Debian and Ubuntu, the equivalent is covered in Understand and use AppArmor: since the LFCS is vendor-neutral, knowing both systems is a real asset.

For kernel parameters, the guide sysctl: harden the Linux kernel and network stack shows how to change a parameter live, make it persistent in /etc/sysctl.d/ and check the result, with the network settings most often needed in practice.

VMs and containers are learnt outside the Linux section

Two objectives of this domain, "Manage Virtual Machines (libvirt)" and "Configure container engines, create and manage containers", are not covered in the Linux section, and that is not an oversight. The site already covers these topics in depth elsewhere, and duplicating them here would produce two versions to maintain that would diverge within a few months.

The Linux course therefore points to these two satellite sections, which are the authority on their subject. You come back for the rest of the block.

For libvirt, virsh (in French) covers list, start, shutdown, define and autostart, which is the objective as such, and create a KVM virtual machine (in French) goes from the disk image to the first boot. For containers, the Podman course (in French) presents the daemonless engine of RHEL distributions, and Quadlet (in French) shows how to turn a container into a systemd service, the most frequent expectation.

The exam will not tell you which engine to use

The LFCS is vendor-neutral: the task talks about containers, not about Podman or Docker. You work with what the exam distribution provides. Practise with Podman, present on RHEL-family distributions and usable without privileges, but know how to find the equivalent with another engine: the run, ps, inspect, logs and exec subcommands are common.

Block 3, Users

Users, groups, sudo, SSH server, LDAP

Official objective (LFCS domain): Create and manage local user and group accounts. Manage personal and system-wide environment profiles. Configure user resource limits. Configure and manage ACLs. Configure the system to use LDAP user and group accounts.

This block also covers sudo and SSH key authentication, which are not objectives of this domain: sudo is named nowhere in the blueprint, and OpenSSH belongs to the Networking domain. They are here because the teaching order calls for it, not because the exam counts them in this 10%.

What it means in practice:

• Create users and groups, manage shells and passwords
• Manage password expiry with chage
• Configure sudo to delegate without granting full root rights
• Define shell profiles in /etc/profile.d/ and ~/.bashrc
• Configure resource limits with ulimit and /etc/security/limits.conf: the Limit a process's resources guide covers soft/hard limits, limits.conf through PAM, systemd's Limit* directives and prlimit
• Apply ACLs: setfacl, getfacl
• Configure SSH key login on the server side, sshd_config, disable password authentication
• Integrate LDAP as an authentication source, examples of tools: sssd, authselect (RHEL-based), ldap-utils (Debian-based)

Companion repository labs:

dsoxlab list-labs --level lfcs --bloc 3

Site guides:

The users and groups guide covers creation, shells and passwords. sudo writes targeted rules, and ACLs detail getfacl, setfacl and the mask. For SSH, the client covers key login and ~/.ssh/config, and the sshd server the sshd_config file, PermitRootLogin and validation with sshd -t.

For the LDAP objective, the guide LDAP, Active Directory and Kerberos: enterprise directories (in French) lays down the concepts of directory, DN and centralised authentication, essential before configuring a client such as sssd.

Block 4, Storage

Partitions, LVM, NFS, autofs, swap, performance

Official objective (LFCS domain): Configure and manage LVM storage. Manage and configure the virtual file system. Create, manage, and troubleshoot filesystems. Use remote filesystems and network block devices. Configure and manage swap space. Configure filesystem automounters. Monitor storage performance.

What it means in practice:

• Identify the disks: lsblk, blkid, fdisk -l
• Create and format partitions (ext4, xfs, vfat)
• Create an LVM volume, extend it, mount it persistently: pvcreate, vgcreate, lvcreate, lvextend
• Make a mount persistent through /etc/fstab with UUID, check with findmnt
• Configure NFS, CIFS and iSCSI as remote file systems (persistence through fstab)
• Configure autofs for dynamic mounting: /etc/auto.master, /etc/auto.*
• Create and enable additional swap: mkswap, swapon
• Storage performance: iostat, iotop, hdparm

Quotas are not part of the current LFCS blueprint

Disk quotas (quotacheck, edquota) are among the useful tools in Linux administration, but they do not appear in the LFCS domains and competencies published today. Do not prioritise them in your LFCS preparation.

Companion repository labs:

dsoxlab list-labs --level lfcs --bloc 4

Site guides:

The partitions guide covers fdisk, parted and formatting. LVM chains pvcreate, vgcreate, lvcreate and lvextend. Mount and make persistent handles the persistent mount with mount, umount, fstab and findmnt, and check disk space and inodes adds df -i, lsof +L1 and tune2fs.

For remote file systems, the Use NFS on Linux guide covers mounting an NFS export, its persistence in /etc/fstab and its check with findmnt. The SMB/CIFS with Samba guide does the equivalent for Windows shares: mount -t cifs with credentials and the vers=3.0 dialect. The Use iSCSI on Linux guide completes it with network block devices: discovering a target, connecting with iscsiadm and mounting persistently. For dynamic mounting, the Automount with autofs guide covers the auto.master maps, the home directory wildcard and unmounting after inactivity.

Block 5, Networking

Addressing, NTP, monitoring, OpenSSH, firewall, reverse proxy

Official objective (LFCS domain): Configure IPv4 and IPv6 networking and hostname resolution. Set and synchronize system time using time servers. Monitor and troubleshoot networking. Configure the OpenSSH server and client. Configure packet filtering, port redirection, and NAT. Configure static routing. Configure bridge and bonding devices. Implement reverse proxies and load balancers.

What it means in practice:

1. Addressing + resolution: ip addr, ip route, hostnamectl, dig, /etc/resolv.conf
2. NTP synchronisation: timedatectl, chronyc tracking, /etc/chrony.conf
3. Network monitoring: ss -tulpn, tcpdump, ping, traceroute, diagnose connectivity
4. OpenSSH server: sshd_config, key authentication, disable password authentication
5. Filtering, NAT, port redirection: permanent rules, masquerade, examples: firewall-cmd --permanent, iptables
6. Persistent static routing, examples: ip route add, network management tools
7. Bridge and bonding: create an aggregated interface or a Linux bridge
8. Reverse proxy and load balancer: configure a front-end service to distribute traffic to backends

Network configuration varies by distribution

The LFCS blueprint describes network skills, not imposed tools. Depending on the exam distribution, the tools differ: nmcli/nmtui on RHEL-based systems, netplan on Ubuntu, interfaces on Debian. Knowing ip as the common denominator is essential.

Companion repository labs:

dsoxlab list-labs --level lfcs --bloc 5

Site guides:

The Networking module sets out ip addr, ip route, ss, ping and dig, the basic commands and the common denominator of every distribution. NetworkManager covers nmcli and nmtui, the tool of RHEL-based systems.

For network filtering, three guides cover the tools you meet depending on the distribution: Configure a firewall with Firewalld for RHEL-based systems (zones, --permanent, --reload), Configure a firewall with nftables for native kernel rules, NAT and port redirection, and Configure a firewall with UFW for Ubuntu.

For static routing, the guide Routing: how packets find their way (in French) explains the routing table, ip route add and route persistence, the blueprint objective as such.

For time synchronisation, the Chrony and NTP: precise synchronisation guide details the NTP configuration in /etc/chrony.conf, the check with chronyc tracking and the link with timedatectl.

For the reverse proxy and load balancing, start with Reverse proxy: definition, role and which tool to choose (in French) to lay down the concept, then practise with Nginx: practical guide (reverse proxy, TLS, performance) (in French) or HAProxy: load balancing and high availability, the two reference tools for this objective.

Often underestimated skills

These topics are in the blueprint but are frequently missing from revision.

Skill	Domain	Common trap
SELinux	Operations	Many disable it, the LFCS requires managing it
libvirt / KVM	Operations	Create and start a VM with virsh
Containers	Operations	podman or nerdctl depending on the exam distro
Recovery after failure	Operations	A wrong /etc/fstab prevents booting; know how to reach rescue mode and remount read-write
Package repositories	Operations	The objective says "repositories", not only "packages": add and validate a source, not just install
Persistent kernel parameters	Operations	A sysctl -w disappears at reboot, the objective explicitly asks for both forms
OpenSSH server side	Networking	Not just the client, configure sshd_config
NAT and port redirection	Networking	Permanent firewalld rules, masquerade
Static routing	Networking	Add a persistent route
Bridge and bonding	Networking	Create a Linux bridge or an aggregated interface
autofs	Storage	Mount on demand, /etc/auto.master
LDAP (clients)	Users	Join an LDAP domain, sssd.conf
Reverse proxy	Networking	Minimal nginx or HAProxy configuration
NTP synchronisation	Networking	chrony, edit /etc/chrony.conf, check with chronyc tracking
SSL/TLS	Essential commands	Generate and inspect a certificate with openssl

Swipe to see more

SELinux, libvirt and reverse proxy: do not ignore them

These three topics are often neglected in revision because they seem advanced or uncommon day to day. Yet they appear explicitly in the published blueprint of the Linux Foundation, checked on 2026-10-01.

Real conditions on the day

Technical environment:

• A single screen allowed, no second monitor
• Private room, clear desk, working webcam required
• The secure PSI Browser is downloaded when the exam is launched; run the PSI system check several days before to validate your hardware
• The base machine is called base, it is your SSH entry point
• Additional hosts can be reached through SSH from base, never through nested SSH
• Use sudo -i to get a root shell

Technical traps to know:

Situation	Rule
base	Never reboot base: rebooting it does not restart the exam environment
certerminal process	Do not stop or tamper with this process, it handles your exam session
Ports not to block	8080/tcp, 4505/tcp, 4506/tcp inbound, including through the firewall rules shipped by default with the distribution
Other hosts	Only base is forbidden from rebooting in the instructions
Copy/paste in the terminal	Use Ctrl+Shift+C / Ctrl+Shift+V in the exam terminal
Closing a tab	Use Ctrl+Alt+W rather than Ctrl+W so as not to close the session

Swipe to see more

Good practices during the exam:

• Read each task in full before starting, the context matters
• Always check the expected effect after each action: systemctl status, ip addr, findmnt, getfacl…
• Go back to base before connecting to another host: nested SSH is not supported

PSI system check, to do before the day

The secure PSI Browser is downloaded when the exam starts. What you must do before: run the PSI Online Proctoring System Check to validate your hardware (webcam, microphone, connection, system) and read the PSI Bridge FAQ. The Linux Foundation recommends doing it several days in advance.

Take the mock exam

Once the skills of the five domains are acquired, put yourself in real conditions with the LFCS mock exam: 17 tasks to complete on Ubuntu 24.04, timed, scored on the state of the system. The threshold is set at 70 out of 100, deliberately above the 67% of the real exam: a margin in training is better.

Mock exam Proof

A hands-on simulation of an assessment

LFCS mock exam, 17 tasks on Ubuntu 24.04

$ dsoxlab run lfcs-mock-exam

Environment: VM·Duration: ~120 min ·Pass mark: 70% of the score

How it is checked: the state of the system is checked after a reboot, not the command you typed.

First time? What DSOXLab is and how to install it

DSOXLab is the command line that prepares a disposable environment (an isolated shell or a VM), runs the lab scenario, then checks the real state of the system and computes a score. Nothing is installed or broken on your workstation.

It needs Python 3.11 or later, uv or pipx, and git. The installation guide details these prerequisites; on Windows, or on a Mac without Python, use the appliance instead.

This lab starts virtual machines: it also needs ansible-playbook, a hypervisor (KVM or Incus), Terraform and hardware virtualization (/dev/kvm), which inside a VirtualBox VM means nested virtualization. The first time, dsoxlab start lfcs-mock-exam checks all of it before creating the machines. Prepare your machine for vm labs.

Install the CLI and add the catalogue, once:

uv tool install dsoxlab   # or: pipx install dsoxlab
dsoxlab catalog add https://github.com/stephrobert/linux-dsoxlab-training

Before you run the lab, check:

• DSOXLab installed
• catalogue available
• compatible environment (isolated shell or VM)

To check, nothing is probed from this page: run dsoxlab doctor. Read the diagnosis

Run this lab, then validate your work:

dsoxlab run lfcs-mock-exam
dsoxlab check lfcs-mock-exam

See every lab: dsoxlab list-labs. Track your progress: dsoxlab progress. The full dsoxlab guide covers scoring and the pitfalls.

What this mock exam tests, and what it samples

The 17 tasks were checked against the official blueprint on 2026-09-15, task by task, then rewritten where they diverged. Three corrections, all verifiable by replaying the lab:

What was tested	Why it was wrong	What replaces it
find and tar, text filtering, links, set-GID directory	It is the old scope of "Essential Commands", which the domain no longer covers	Git, repairing a broken service, recovering the space held by a deleted but still open file, producing an SSL certificate
Delegating sudo	sudo is named nowhere in the blueprint	POSIX ACLs, named entry and default entry, which are an objective
A disk quota	Quotas belong to no LFCS objective, and this page already said so further up	Automounting, the "Configure filesystem automounters" objective

Swipe to see more

The mock exam therefore no longer scores anything outside the reference. It samples part of it, exactly like the real exam, which draws 17 to 20 tasks from the 34 objectives published.

What it does not draw, and must therefore be worked on elsewhere: kernel parameters, recovery after failure, libvirt VMs, container engines and SELinux on the Operations side; NTP, OpenSSH, bridge and bonding and the reverse proxy on the Networking side; environment profiles, resource limits and LDAP on the Users side; remote file systems and storage performance on the Storage side.

Treat it for what it is: training in exam conditions, timer and persistence included, on a faithful sample of the reference. For the objectives not drawn, the guides and labs of the five blocks above remain the reference.

Key points

• The LFCS is a 100% hands-on exam on a real Linux terminal; practise in a real environment (VM or KVM lab), not only in an online simulator.
• The blueprint is vendor-neutral: the skills are described as objectives, not imposed tools; depending on the distro, the commands may vary.
• The networking and operations domains alone make up 50% of the score, do not neglect them.
• The built-in documentation (man, /usr/share) and the distribution packages are allowed during the exam: learn to navigate them quickly.
• Never reboot base, do not stop certerminal, do not block inbound ports 8080/4505/4506.
• The Killer.sh simulator offers the same scenarios in both its sessions; use it to get familiar with the interface, not to predict the real exam.
• Each task must survive a check: after each action, verify the effect with systemctl status, ip addr, findmnt, getfacl, etc.
• Disk quotas are not part of the current LFCS blueprint, do not prioritise them.

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