Chapter 4: Basic Commands

Basic Commands in Bash — the absolute foundation.

Think of these as the “alphabet” of the terminal. Once you know these 15–20 commands really well, 80% of your daily terminal work becomes easy and fast. We’ll go slow, explain like friends in Hyderabad, show exact examples, what they do, common mistakes, and useful options.

Open your terminal now (Ctrl + Alt + T on Ubuntu, Terminal on macOS, Git Bash on Windows).

Important teacher tip first:

• Press Tab key after typing part of a command or folder name → Bash auto-completes (magic!)
• Press ↑ (up arrow) → see previous commands
• Type history → see list of past commands
• Wrong command? Just press Ctrl + C to stop and try again

Navigation & Location Commands (The Most Used Ones)

1. pwd → Print Working Directory (Where am I right now?)

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   pwd

   Example output: /home/webliance or /home/webliance/bash_class

   → Always know your location before doing anything!

2. ls → List files and folders

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   ls

   → Shows normal files/folders

   Better versions (use these daily!):

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   ls -l          # long format: shows permissions, size, date ls -la         # shows hidden files too (files starting with .) ls -lah        # human-readable sizes (KB, MB instead of bytes) ls --color=auto # colors folders blue, executables green (most terminals do this auto)

   Example:

   text

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   webliance@ubuntu:~$ ls -la drwxr-xr-x  5 webliance webliance 4096 Feb 25 13:10 . drwxr-xr-x 20 webliance webliance 4096 Feb 25 12:00 .. -rw-r--r--  1 webliance webliance  220 Feb 25 13:05 hello.sh drwxrwxr-x  2 webliance webliance 4096 Feb 25 13:15 my_folder

3. cd → Change Directory (Go somewhere else)

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   cd my_folder          # go inside "my_folder" cd ..                 # go one level up (parent folder) cd ~                  # go to your home (same as just typing cd) cd /                  # go to root (top level of whole system) cd ~/Downloads        # go to Downloads in your home cd -                  # go back to previous folder you were in

   Pro tip: cd with no argument = go home

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   cd pwd   # → /home/webliance

File Creation & Viewing

4. touch → Create empty file or update timestamp

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   touch notes.txt touch report_2026.txt backup.sh

5. cat → Show content of file (concatenate)

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   cat notes.txt cat file1.txt file2.txt   # shows both one after another

   Good for small files. For big files use less or more (next).

6. echo → Print something on screen (very useful in scripts too)

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   echo "Hello Hyderabad!" echo "Today is $(date)"          # runs date command inside echo $HOME                       # shows your home path

7. mkdir → Make Directory

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   mkdir project mkdir -p parent/child/grandchild   # creates all folders at once

8. rmdir → Remove empty directory

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   rmdir empty_folder

Copy, Move, Rename, Delete

9. cp → Copy files/folders

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   cp old.txt new.txt             # copy file cp -r folder1 folder2          # copy folder + everything inside (-r = recursive) cp *.jpg ~/Pictures/           # copy all jpg files to Pictures

10. mv → Move or Rename

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    mv oldname.txt newname.txt     # rename mv file.txt ~/Documents/       # move to another folder mv -i file.txt backup/         # -i asks before overwrite (safe!)

11. rm → Remove (delete) — be careful!

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    rm file.txt                    # delete file rm -r folder                   # delete folder + contents rm -rf folder                  # force delete, no questions (dangerous!) rm -i *.tmp                    # asks before deleting each (.tmp files)

    Teacher warning: No recycle bin in terminal — deleted = gone forever. Use -i when learning!

Help & Information

12. man → Manual (help page) for any command
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    man ls man cp

    → Press q to quit, / to search inside

13. –help → Quick help
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    ls --help

14. whatis / which
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    whatis ls          # short description which ls           # shows where the command lives (/usr/bin/ls usually)

Quick Useful Extras (Beginner Friendly)

15. clear → Clear the screen
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    clear

16. date → Show current date/time
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    date date +"%Y-%m-%d"   # nice format: 2026-02-25

17. whoami → Who am I logged in as?
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    whoami   # → webliance

18. df -h → Disk free space (human readable)
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    df -h

19. free -h → Memory (RAM) usage
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    free -h

20. history → See past commands
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    history | tail -10   # last 10 commands

Practice Session Right Now (5 Minutes!)

Create a playground:

See? You just used 10+ commands!

Quick Reference Table (Copy to your notes!)

Master these → next we’ll do pipes (), grep, redirection (> , >>), and small scripts.

Any command confusing? Type it wrong and got error? Tell me — we’ll fix together! Or say: “Teacher, explain ls options more” or “give practice exercises”

You’re doing great — keep typing every day! 🐧🚀 From Hyderabad with love! 😄