CELE case studies
CELE · Put your knowledge to work in context.
The Certified Entry-Level Linux Professional (CELE) is an early-career credential for people who can already work at a Linux shell and want independent evidence of that skill. It suits career changers coming from help desk or Windows administration, students finishing a first Linux course, and junior staff who need a structured target before moving on to deeper administration certifications. The exam is multiple choice, so it rewards precise recall of commands, file locations, and configuration behaviour rather than hands-on lab work alone. Its published blueprint spans nine areas: core concepts and architecture, installation and configuration, filesystem navigation and file management, users, groups and permissions, processes and services, networking and remote access, package management, shell scripting and command-line utilities, and security basics. The CELE case studies are 5 cases and about 2,560 words.
1Intermittent Freezes on a 4 GB Web Server
Acme Retail runs its storefront on a cloud VM with 2 vCPUs, 4 GB RAM, and a 40 GB SSD. The stack is Nginx, PHP-FPM with 8 workers, and MySQL 8.
540 words, about 3 min2PHP Version Conflict on Ubuntu 22.04 Web Server
Your company runs a customer portal on Ubuntu Server 22.04 (2 GB RAM, 2 vCPU). The application vendor now requires PHP 8.2, but the distribution repository provides PHP 8.1.
498 words, about 2 min3Shared Project Directory with Wrong Group Ownership
Five developers-alice, bob, carol, dave, and erin-share /srv/proj on a Linux server. The directory is owned by root:proj and was set to mode 2770 yesterday.
536 words, about 3 min4Custom Service Starts Before NFS Mount on Boot
A custom Python application runs as myapp.service on a Linux server. It reads and writes /mnt/nfs/data , an NFS mount defined in /etc/fstab with netdev .
443 words, about 2 min5SSH Brute Force on an Internet-Exposed Server
A Linux server in a small office is exposed to the internet on port 22 for remote administration. /var/log/auth.log shows 2,000 failed password attempts per day from many IPs, mostly trying root and common usernames.
543 words, about 3 min