Linux Labs
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Users, permissions, and processes

From file permissions and accounts to sudo, groups and processes.

13 stages6 labs~7 hours medium medium

Progress Stages: 0 of 13

The track has not been started. The first stage is «Users, groups, and process identity», ~30 min.

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Module 1

Users and permissions

Who a command runs as, reading rwx on files and directories, where on the path access breaks and how to fix it with chmod and chown without opening too much. Plus a team's shared directory: setgid, sticky, and the umask.

5 stages · ~3 hours

  1. Stage 1 of 13

    1 · Users, groups, and process identityUsers, groups, and process identity

    7 steps · ~30 min 7 steps · ~30 min
    1. The weekly summary exercises 0 of 1 on a machine 4 min
    2. 2 Who opens the file on a machine 5 min
    3. 3 Name, UID, and groups on a machine 6 min
    4. 4 Who owns the file on a machine 4 min
    5. 5 What sudo changes theory 4 min
    6. 6 Test as the user who needs access on a machine 6 min
    7. 7 Summary summary 1 min
    Start stage 1
  2. Stage 2 of 13

    2 · File and directory permissionsFile and directory permissions

    6 steps · ~30 min 6 steps · ~30 min
    1. Your file, someone else's read exercises 0 of 1 on a machine 5 min
    2. 2 The permission string on a machine 5 min
    3. 3 One triple applies on a machine 5 min
    4. 4 Directory permissions on a machine 8 min
    5. 5 The whole path is checked on a machine 5 min
    6. 6 Summary summary 2 min
    Start stage 2
  3. Stage 3 of 13

    3 · Changing and diagnosing permissionsChanging and diagnosing permissions

    8 steps · 1 lab · ~45 min 8 steps · 1 lab · ~45 min
    1. The script from the note exercises 0 of 1 on a machine 5 min
    2. 2 chmod: whom and what on a machine 6 min
    3. 3 Mode as a number on a machine 5 min
    4. 4 Fix the place where access breaks on a machine 4 min
    5. 5 A file's owner and group on a machine 5 min
    6. 6 Check the fix theory 4 min
    7. 7 Wrong file permissions easy lab 15 min
    8. 8 Summary summary 1 min
    Start stage 3
  4. Stage 4 of 13

    4 · A shared directory: setgid, sticky, and umaskA shared directory: setgid, sticky, and umask

    7 steps · 1 lab · ~55 min 7 steps · 1 lab · ~55 min
    1. The team's shared folder exercises 0 of 1 on a machine 5 min
    2. 2 The group of a new file on a machine 6 min
    3. 3 The mask for new files on a machine 8 min
    4. 4 Others' files stay put on a machine 6 min
    5. 5 An inbox for reports on a machine 3 min
    6. 6 The team's shared directory medium lab 25 min
    7. 7 Summary summary 2 min
    Start stage 4
  5. 5 · Module test 10 questions · pass mark 70%

Module 2

User administration and sudo

An account is a line in /etc/passwd: create one, close login for a leave and open it again, grant and revoke a group without touching the others, and allow exactly one command through sudo.

4 stages · ~2 hours

  1. Stage 6 of 13

    6 · Accounts and their lifecycleAccounts and their lifecycle

    7 steps · ~30 min 7 steps · ~30 min
    1. A directory, but no user exercises 0 of 1 on a machine 4 min
    2. 2 An account is a line in a list on a machine 4 min
    3. 3 Create an account on a machine 5 min
    4. 4 Service accounts and nologin on a machine 6 min
    5. 5 Suspend and keep the data theory 5 min
    6. 6 Reopen the account on a machine 4 min
    7. 7 Summary summary 2 min
    Start stage 6
  2. Stage 7 of 13

    7 · Managing group membershipManaging group membership

    6 steps · ~30 min 6 steps · ~30 min
    1. A group request exercises 0 of 1 on a machine 5 min
    2. 2 Primary and supplementary groups on a machine 5 min
    3. 3 Add without losing anything on a machine 5 min
    4. 4 The account changed, the process did not on a machine 6 min
    5. 5 Revoke one group on a machine 7 min
    6. 6 Summary summary 2 min
    Start stage 7
  3. Stage 8 of 13

    8 · Delegating commands with sudoDelegating commands with sudo

    8 steps · 2 labs · ~1 hour 8 steps · 2 labs · ~1 hour
    1. Two lines yes, three no exercises 0 of 1 on a machine 6 min
    2. 2 What a rule is made of on a machine 6 min
    3. 3 Syntax and meaning on a machine 6 min
    4. 4 The rule file theory 5 min
    5. 5 Check both boundaries on a machine 5 min
    6. 6 Grant sudo to a user easy lab 10 min
    7. 7 Suspend a user account easy lab 20 min
    8. 8 Summary summary 2 min
    Start stage 8
  4. 9 · Module test 10 questions · pass mark 70%

Module 3

Processes and signals

How to find the process that keeps the CPU busy and whoever started it, free the terminal from a long command, and stop a program so that it saves its work. And why kill cannot touch a zombie.

4 stages · ~2 hours

  1. Stage 10 of 13

    10 · Observing processesObserving processes

    7 steps · ~30 min 7 steps · ~30 min
    1. The site is slow exercises 0 of 1 on a machine 4 min
    2. 2 Processes you never started on a machine 5 min
    3. 3 A process row in ps on a machine 5 min
    4. 4 Process state on a machine 6 min
    5. 5 CPU in top and ps theory 4 min
    6. 6 Who started the load on a machine 4 min
    7. 7 Summary summary 2 min
    Start stage 10
  2. Stage 11 of 13

    11 · Background jobs and the terminalBackground jobs and the terminal

    7 steps · ~30 min 7 steps · ~30 min
    1. You need the terminal for something else exercises 0 of 1 on a machine 5 min
    2. 2 Background and the job number on a machine 6 min
    3. 3 Pause and return on a machine 6 min
    4. 4 Job number and PID theory 4 min
    5. 5 Wait for the result on a machine 3 min
    6. 6 The export took over the terminal on a machine 4 min
    7. 7 Summary summary 2 min
    Start stage 11
  3. Stage 12 of 13

    12 · Signals and process terminationSignals and process termination

    9 steps · 2 labs · ~1 hour 9 steps · 2 labs · ~1 hour
    1. The exports have to stop exercises 0 of 1 on a machine 4 min
    2. 2 A request and an order theory 5 min
    3. 3 Pause: STOP and CONT on a machine 3 min
    4. 4 Someone else's process theory 4 min
    5. 5 A process you cannot kill on a machine 8 min
    6. 6 Stop the right export on a machine 4 min
    7. 7 The server is sluggish medium lab 20 min
    8. 8 A process that will not go away medium lab 20 min
    9. 9 Summary summary 2 min
    Start stage 12
  4. 13 · Module test 10 questions · pass mark 70%

  1. Final lab

    Wrong file permissions ~15 min
  2. Final test 18 questions · pass mark 80%

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