Understand how Linux works at the level of processes, filesystems, users, permissions, and systemd. Write shell scripts that automate real tasks. Become comfortable living in the terminal. Rails runs on Linux. Understanding processes, file descriptors, and signals helps you debug Puma and Sidekiq in production. When Puma's worker gets killed by the OOM killer, you need to understand `/proc/<pid>/oom_score`. When Sidekiq stops processing jobs, you need `ps aux | grep sidekiq` and `kill -USR1`. When disk fills up because of log rotation failure, you need to understand `/var/log` and `logrotate`. Module 0 gives you these skills. | Rails Situation | Linux Skill | |----------------|-------------| | Puma memory bloat | `ps aux`, `/proc/pid/status`, OOM killer | | Sidekiq stuck jobs | `kill -USR1`, `strace -p` | | Disk full | `df -h`, `du -sh`, `logrotate` | | Permission denied | `chmod`, `chown`, `ls -la` | | App won't start on boot | `systemd`, `journalctl -u myapp` | | SSH key issues | `~/.ssh/authorized_keys`, `sshd_config` |
You have been SSH-ing into servers for nine years. You have restarted Puma, tailed logs, killed runaway processes, and grepped through production output at 2 AM. But here is the t…
Approach: READ Ch 1-11
Approach: SKIM for gaps
Approach: SELECTIVE: shell scripting + automation chapters
Work through each item before the checkpoint.
SSH into an Ubuntu VM (use Multipass or AWS free tier). Install Ruby, PostgreSQL, Redis, and Nginx. Deploy a Rails app manually (no Docker, no Capistrano). Understand every step: …
6 lessons. Read in order; spiral back when you need to. By the end you'll have used the core ideas twice — once on the abstract, once on something you'll meet at work next week.