The Command Line: Linux for People Who Avoided It

By the end

What you'll build

• Explain what a shell does and read any command as program, options and arguments
• Navigate a filesystem using absolute paths, relative paths and the . .. ~ shortcuts
• Create, copy, move and delete files safely, including the checks that prevent a bad recursive delete
• Read and search large log files with cat, head, tail, less and a live tail -f
• Locate files by name, age and size with find, and search inside them with grep and basic regular expressions
• Redirect stdout and stderr, read an exit code, and build multi-stage pipelines with wc, sort, uniq and cut
• Read an ls -l permission line and set permissions with both the numeric and the symbolic form of chmod
• Diagnose a busy or full machine using ps, kill, df, du and free, and pack directories with tar
• Set environment variables, explain how PATH finds a program, and describe how ssh key pairs authenticate
• Write and schedule a shell script with a shebang, arguments, guard clauses and deliberate exit codes

Curriculum

What's inside

7 modules · 48 lessons

1. 01

   Meet the shell

   6 lessons
   • Start here: what this course is, and what it is not
   • What a shell is, and why typing beats clicking
   • Anatomy of a command: program, options, arguments
   • Drill: your first commands — pwd, ls and cdcli builder
   • Helping yourself: --help, man pages and reading a synopsis
   • + 1 more lesson
2. 02

   The tree, and how to say where you are

   6 lessons
   • One root, many branches: the filesystem tree
   • Absolute and relative paths
   • Three shortcuts you will type all day: `.`, `..` and `~`
   • Drill: move around the treecli builder
   • Practice: which path lands where?fill blank
   • + 1 more lesson
3. 03

   Make it, move it, remove it

   6 lessons
   • Making things: mkdir and touch
   • Drill: build the project skeletoncli builder
   • Copy and move: cp, mv, and the trailing-slash trap
   • Drill: copy and move preciselycli builder
   • rm, rmdir, and the real danger of `-rf`
   • + 1 more lesson
4. 04

   Read files, find things

   7 lessons
   • Four ways to read a file: cat, head, tail and less
   • Watching a log as it happens: tail -f
   • Drill: read a log four wayscli builder
   • find: locating files by name, age and size
   • Drill: find the filecli builder
   • + 2 more lessons
5. 05

   Streams, pipes and shaping data

   7 lessons
   • Where output goes: stdout, stderr and the exit code
   • Redirection: sending output where you want it
   • Drill: send output where you want itcli builder
   • The pipe: one program's output becomes another's input
   • The shaping toolkit: wc, sort, uniq and cut
   • + 2 more lessons
6. 06

   Permissions, privilege and processes

   8 lessons
   • Users, groups, and reading an `ls -l` line
   • chmod in numbers: 4, 2, 1
   • chmod in letters: u, g, o and +/-
   • Drill: set permissions properlycli builder
   • Least privilege: why 777 is not a fix, and sudo is not a habit
   • + 3 more lessons
7. 07

   Housekeeping, remote work and your first script

   8 lessons
   • When the disk fills up: df, du, free — and tar
   • Environment variables and PATH
   • Working on a machine that is not yours: ssh and key pairs
   • cron: work that happens without you
   • Drill: disk, archives, PATH, ssh and croncli builder
   • + 3 more lessons

The shape of it

How this course works