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PURPLEDUEL

Linux Fundamentals path

9 labs · Shell, files, filters, permissions

Linux Fundamentals is the starting point. Almost every server, network device and security tool runs on Linux, and anyone who defends a system (or tests it with permission) spends much of their time in a terminal. Here you learn to move around the filesystem, find hidden files, read huge logs piece by piece, search for words with grep, chain commands with pipes and understand permissions, environment variables and history: the basics you will use in every other path.

The labs, in order

  1. First steps in the shell

    easy · 300 XP

    Get comfortable with the command line. Explore the filesystem and find the flag hidden in one of the folders.

    No other lab required.

  2. Where am I? Absolute and relative paths

    easy · 320 XP

    The treasure is not in your home folder. Follow the chain of clues: each one tells you where to find the next, sometimes with a relative path, sometimes with an absolute one. Learn to always know where you are.

    Requires: First steps in the shell.

  3. Hidden files

    easy · 320 XP

    Your home folder looks almost empty, but it isn't. Learn to reveal what ls keeps hidden and find the key to the hiding place.

    Requires: Where am I? Absolute and relative paths.

  4. Reading in pieces

    easy · 300 XP

    The build server left a huge log. You don't need to read it all: learn to look only at the beginning and the end, to measure how long it is, and find the release code.

    Requires: Hidden files.

  5. Searching text

    medium · 600 XP

    You inherited Marta's notes and mailbox. Somewhere in there is the token for the server room, but nobody remembers which email it is in. Don't read everything: search for the right words with grep.

    Requires: Reading in pieces.

  6. Finding files

    medium · 600 XP

    The office archive is a maze of folders. A file with an exact name holds the key to the server room locker: don't hunt for it by hand, let the shell do the searching.

    Requires: Searching text.

  7. Pipes and filters

    medium · 600 XP

    A radio repeater picked up the same message dozens of times, but interference ruined many copies. Count and sort the lines with a chain of commands to find out which message is the true one.

    Requires: Finding files.

  8. Permissions and owners

    medium · 600 XP

    Not every file is for everyone. Learn to read permissions (rwx) with ls -l, find out what you cannot open, and track down the right script to run to get the delivery code.

    Requires: Finding files.

  9. Environment and history

    medium · 600 XP

    You took over from a colleague and he left you his shell. Query the environment and the command history to recover the production database credentials... and find out why they must never be typed on the command line.

    Requires: Permissions and owners.

Commands in this path

Along this path the simulated terminal has you use these commands: ls, cat, cd, pwd, wc, head, tail, grep, find, base64, cut, sort, uniq, env, echo and history. Each lab page explains what they are for.

Learn more with the guides

All guides

The other paths

The PurpleDuel labs