Linux from zero: the command line

Finding your way 5 topics

• Scene 0: your first morning at Harbour Street
  Forty-five minutes of clicking, dragging and typing a few commands in a simulated machine: every kind of activity in the course, and nothing to install.
• What Linux is, and what the terminal does
  What an operating system, a kernel and a distribution are; the terminal and the shell; the prompt; the anatomy of a command; whoami, hostname, date, echo and man; and…
• Folders, files and paths
  The single file tree and its main folders, pwd, ls and cd, absolute and relative paths with the shortcuts . .. and ~, and ls options.
• Making and moving things
  mkdir (with -p), touch, cp (with -r), mv for moving and renaming, rm (with -r), wildcards, and the habits that keep deleting safe.
• Looking inside files
  cat, head, tail and less; counting with wc; file and stat; writing with > and >>; editing with nano; and comparing with diff.

Working with text 4 topics

• Searching text: grep and find
  grep and its options, patterns with ^ $ . and [ ], and find for files by name and type.
• Pipes and redirection
  Pipes that join commands, stdin, stdout and stderr, redirection with > >> < and 2>, tee, and building pipelines step by step.
• Sorting, counting and picking columns
  sort, uniq -c, cut, awk and tr and sed in simple use, and the sort | uniq -c | sort -nr pattern for top-N lists.
• Real text jobs: a workshop
  A method for text questions, and three worked jobs: pages with errors, users with failed logins and a lookup, combining grep, awk, cut, sort, uniq, head, xargs and…

People, permissions and programs 4 topics

• Users and groups
  Users and user numbers, /etc/passwd, the root user and sudo with least privilege, groups, and the commands useradd, groupadd and usermod -aG.
• Permissions: who may do what
  Reading ls -l, r w x as 4 2 1, chmod with numbers and letters, how folders differ, chown and chgrp, running scripts, and diagnosing Permission denied.
• Processes and jobs
  What a process is, ps and top, finding the process that uses the processor, kill and signals, pgrep and pkill, and foreground and background jobs.
• Software and updates
  Packages, repositories and dependencies; apt update, search, show, install, remove and upgrade; why updates are security; and installing only from trusted sources.

Doing it more than once 4 topics

• Variables and the environment
  Shell variables, quoting, export and the environment, PATH and which, aliases, startup files, and history and shortcuts.
• Your first scripts
  Writing a script with a shebang, arguments, if and for, exit status, and habits for safe scripts.
• Scheduling a task with cron
  How cron and the crontab work, the five time fields and their special characters, crontab -l and -e, full paths and logging, and checking why a job did not run.
• Putting it together: the weekly tidy-up
  A project: back up the member list and rules into a private dated archive with tar, remove drafts, keep a log, and schedule it with cron, planning each step and asking…

Infrastructure behind your machine 4 topics

• The infrastructure map: what a Linux machine is made of
  The parts of a Linux machine: hardware, kernel, shell, file system, processes, users and permissions, and the package manager, with a card for each and the path of one…
• Storage and the file system tree
  Disks, partitions, file systems and mount points; df and du; the arithmetic of a full disk; failure drills; backups and restore tests.
• Processes, memory and the scheduler
  How the scheduler shares cores, memory and swap, the load average and available memory, what happens when memory runs out, failure drills, and sizing with numbers you…
• Running and watching a Linux machine
  Logs and log rotation, monitoring and alerts, backups and restore tests, updates and access control, a one-page runbook and a handover note.

Interview ready 2 topics

• Interview ready: the command line and files
  The questions people really ask about the command line, files, permissions and accounts, with model answers, timed terminal tasks and a mock round.
• Interview ready: text, scripts and troubleshooting
  The questions people really ask about text pipelines, scripts, cron, processes and troubleshooting, with model answers, timed terminal tasks and a mock round.

The weekly job

A tested shell script that backs up a folder into a private archive, tidies old files and writes a log, scheduled with cron.

Machine card sheet

Seven cards for the parts of a Linux machine, a disk estimate, one failure drill and a recorded self-review of one interview answer.

Why take this course

• Learn Linux with nothing to install
• Type real commands in a simulated machine on every page
• Understand the machine as well as the commands

You will build

• A tidy file structure and a text report
• A shell script and a cron job
• A one-page runbook and a tested backup plan

What you can do afterwards

• Work confidently at a Linux terminal
• Explain what you are doing and why
• Answer common Linux interview questions and complete timed tasks