M2 — Accounts, login, and first commands

Module brief#

Learn how accounts and home directories work, how to read command syntax (command, options, arguments), and how to get help from man without guessing.

Learning objectives#

Change your own password safely with passwd
Switch user context with su / su - (when permitted)
Navigate to home with cd, cd ~, and cd ~username
Break a command line into command, options, and arguments
Use man, man -k, and section numbers to learn a utility
Run everyday status commands: uname, date, cal, clear, ls

1. Accounts and your home directory#

After you log in — whether through a graphical greeter, a virtual console, WSL, or SSH — you land in a shell as some user. Examples in this course use student or labuser. Your real name may differ.

Each ordinary user normally has a home directory under /home. Shortcuts:

cd          # go to your home directory
cd ~        # same idea — tilde means your home
cd ~student # go to student\'s home (if you have permission)

Check who you are and where home is:

whoami
id
echo $HOME

Example:

box
uid=1000(box) gid=1000(box) groups=1000(box)
/home/box

2. Changing your password#

Use passwd with no username to change your own password. You will be prompted for the current password, then the new one twice. Nothing echoes as you type — that is normal.

passwd

Administrators can reset other accounts’ passwords; that needs privilege and is outside day-one practice. Never paste real passwords into chat, tickets, or screenshots.

3. Switching users with `su`#

su means “substitute user”.

Form	Typical effect
`su student`	Switch to `student`, keep much of your current environment
`su - student`	Switch to `student` as a login shell (loads that user’s environment, starts in their home)
`su -` or `su - root`	Become root as a login shell (requires root password or sudo policy)

On many modern desktops, day-to-day admin work uses sudo instead of a root password. If su asks for a password you do not have, stop and use the method your admin documented.

4. Command syntax: command, options, arguments#

A typical line looks like:

command  [options…]  [arguments…]

Example:

ls -l /tmp/linux-lab-pushpjeet

command: ls — the program to run
option: -l — modify behaviour (long listing)
argument: /tmp/linux-lab-pushpjeet — what to operate on

Options often start with - (short) or -- (long). Many commands accept both (-a and --all).

Try a few safe “status” commands:

uname -a
date
cal
clear    # clears the terminal screen; no output to paste
ls
ls -l

Sample outputs from a practice host:

uname -a

Linux grok-bot-vm-270875175 6.12.94+ #1 SMP PREEMPT_DYNAMIC Wed Sep 23 20:54:12 UTC 2026 x86_64 GNU/Linux

date

Sat Sep 26 11:04:52 IST 2026

cal

   September 2026
Su Mo Tu We Th Fr Sa
       1  2  3  4  5
 6  7  8  9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30

If cal is missing on a minimal image, install the calendar package for your distro (ncal / bsdmainutils on Debian/Ubuntu, or the equivalent on RHEL-family) — or simply rely on date for now.

5. Getting help with `man`#

Manual pages are the built-in textbook. Try:

man ls

The pager opens. Useful keys in less (the usual pager):

Key	Action
Space / `f`	Forward a page
`b`	Back a page
`/text`	Search forward for `text`
`n`	Next search hit
`q`	Quit

The top of man ls looks like:

LS(1)                        User Commands                       LS(1)

NAME
       ls - list directory contents

SYNOPSIS
       ls [OPTION]... [FILE]...

DESCRIPTION
       List information about the FILEs (the current directory by default).
…
       -a, --all
              do not ignore entries starting with .

Read the SYNOPSIS and DESCRIPTION first. Skim options when you need a flag.

Sections#

Manual pages are grouped by section number. You will see LS(1) — section 1 is user commands. Other common sections: 5 file formats, 8 admin commands.

man 1 ls          # section 1 explicitly
man -k list       # keyword search (apropos)
man -f ls         # whatis-style short description

Examples:

man -f ls

ls (1)               - list directory contents

man -k list | head

dir (1)              - list directory contents
ls (1)               - list directory contents
…

If man says “nothing appropriate,” the pages may not be installed on a slim container image. On a normal Ubuntu or RHEL-family desktop/server install they are usually present. You can also try ls --help for a short option list:

ls --help | head -15

Usage: ls [OPTION]... [FILE]...
List information about the FILEs (the current directory by default).
…
  -a, --all                  do not ignore entries starting with .
  -A, --almost-all           do not list implied . and ..

6. A first look at `ls -l`#

ls -l /tmp/linux-lab-pushpjeet

You will see permissions, link count, owner, group, size, timestamp, and name. Module 3 goes deeper on paths and listing flags; Module 12 covers permissions in detail. For now, treat ls -l as “tell me more about each entry.”

Practice: MCQs#

Q1. In ls -l /etc, what is the argument?

A) ls
B) -l
C) /etc
D) The Enter key

Answer

C. -l is an option; /etc is the path argument; ls is the command.

Q2. What does man -k passwd do?

A) Changes your password
B) Searches man page short descriptions for the keyword passwd
C) Deletes the passwd database
D) Opens section 8 only

Answer

B. -k is keyword search (like apropos). Changing passwords uses the passwd command itself.

Q3. Why does passwd show no stars while you type?

A) The keyboard is broken
B) Linux never accepts passwords
C) Hiding keystrokes is normal; type carefully and confirm when asked
D) You must be root for any password change

Answer

C. Lack of echo is a security habit. Ordinary users change their own password without being root.

Q4. su - labuser is preferred over plain su labuser when you want:

A) A faster prompt colour
B) A login-style environment for labuser (home and profile scripts)
C) To delete labuser
D) To avoid entering any password ever

Answer

B. The dash requests a login shell for the target account.

Q5. You see BASH(1) in a man page header. The (1) means:

A) Version 1 of bash only
B) Manual section 1 (user commands)
C) One matching file on disk
D) Priority level 1 for the CPU

Answer

B. Section numbers classify man pages. User commands are typically section 1.

Practice: Flashcards#

Front	Back
`passwd`	Change your account password interactively
`su - user`	Switch user with a login shell
`cd ~`	Change to your home directory
Option vs argument	Option changes behaviour (`-l`); argument is the target (`/etc`)
`man cmd`	Open the manual page for `cmd`
`man -k word`	Keyword search across man short descriptions
`man -f cmd`	Short one-line description (whatis)
`uname -a`	Print detailed system/kernel information
`cal`	Display a calendar
Pager key `q`	Quit `man` / `less`

Practice: Fill in the blank#

To open the manual for ls, type: ________ ls
Keyword search for manuals mentioning “directory”: man ___ directory
Long listing of /tmp: ls ___ /tmp
Go to your home directory using a tilde: cd ___
Print a full system identifier string: uname ___

Answers

man
-k
-l
~
-a

Practice: Mini terminal challenge#

Challenge: Learn one new `ls` flag from man#

Goal: Use the manual instead of a search engine for one flag.

Setup: Terminal with man available.

Tasks:

Run man ls and quit with q once you can navigate.
Search inside the page for human or read about -h / --human-readable if present.
Run ls -lh /tmp (or your lab directory) and note how sizes appear.
Run man -f date and date itself; confirm the short description matches the behaviour.

Verify: You can explain one ls option you did not know before this challenge.

Stretch: Run man man and find how to force a section number.

Hands-on lab#

Goal: Comfort with accounts, syntax, and man.

Steps:

Record whoami, id, and $HOME in your lab notes.
If allowed on your personal account, run passwd and set a strong password you will remember (skip on shared demo accounts you do not own).
Run three commands that each use at least one option: e.g. uname -a, ls -l, date -u (UTC time).
Open man ls, find the option for showing hidden files, then run it.

Verify: ls -a shows . and .. (and other dotfiles if any). Your notes list command / option / argument for one example line.

Stretch: Compare su student vs su - student on a VM where you have a second account — observe $HOME and pwd after each.

Common mistakes#

Typing passwords into the shell prompt by accident (password prompts look similar — read carefully)
Closing man with Ctrl+C instead of q (Ctrl+C may work but q is the intended pager exit)
Assuming --help and man always exist on every minimal container (install docs packages when needed)
Using su to become root for ordinary file practice

Summary#

You can navigate home, reason about command syntax, change your password, and learn tools from man. Those habits unlock every later module.

Continue

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Module brief#

Learning objectives#

1. Accounts and your home directory#

2. Changing your password#

3. Switching users with su#

4. Command syntax: command, options, arguments#

5. Getting help with man#

Sections#

6. A first look at ls -l#

Practice: MCQs#

Practice: Flashcards#

Practice: Fill in the blank#

Practice: Mini terminal challenge#

Challenge: Learn one new ls flag from man#

Hands-on lab#

Common mistakes#

Summary#

Continue

3. Switching users with `su`#

5. Getting help with `man`#

6. A first look at `ls -l`#

Challenge: Learn one new `ls` flag from man#