Day 1 – Terminal Navigation and Core Commands

Today's Focus

Learn to navigate the filesystem and manipulate files entirely from the terminal using a core set of commands, then write and run your first shell script.

Commands

CommandDescription
pwdPrint the current working directory (your location in the filesystem).
lsList the contents of a directory. Use -l for details and -a to show hidden files.
cdChange directory. cd ~ goes home, cd .. goes up one level, cd - returns to the previous location.
mkdirCreate a directory. Use -p to create nested directories in one command.
touchCreate an empty file, or update the timestamp of an existing one.
echoPrint text to the terminal. Use > to write to a file and >> to append.
catPrint the contents of a file to the terminal.
cpCopy a file or directory. Use -r to copy a directory and its contents.
mvMove or rename a file or directory.
rmDelete a file. There is no undo — deleted files do not go to a trash folder.
rmdirRemove an empty directory. Safer than rm -rf because it refuses to delete a directory that still has contents.
rm -rfForcefully and recursively delete a directory and everything inside it. Use with extreme caution — it will permanently destroy files with no confirmation prompt and no recovery. Never run it as root or against /.
chmodChange file permissions. chmod +x makes a file executable.

Tasks

  • Open your terminal. Run pwd to see where you are, then ls to list the contents. Run ls -l and ls -la and note what the extra flags reveal.

  • Use cd to move around: cd ~ to go home, cd .. to go up one level, cd - to return to the previous directory. Run pwd after each move to confirm where you are.

  • Create a deep directory structure in one command: mkdir -p ~/academy/week-01/project/src/utils. Navigate into it using cd and back out again.

  • Use touch to create several files: touch README.md main.sh config.txt. Verify they exist with ls -l.

  • Use echo to write content into a file: echo "Hello, World!" > hello.txt. Read it back with cat hello.txt.

  • Use echo to append a second line without overwriting: echo "Goodbye, World!" >> hello.txt. Confirm both lines are there with cat.

  • Copy a file with cp hello.txt hello-copy.txt. Rename it with mv hello-copy.txt hello-backup.txt. Delete it with rm hello-backup.txt.

  • Create a script file called hello.sh containing the following:

    #!/bin/sh
echo "Hello, World!"

    Try running it with sh hello.sh. Then make it directly executable: chmod +x hello.sh and run it with ./hello.sh. Observe the difference.

  • Tidy up: delete individual files with rm, then remove an empty directory with rmdir. Notice that rmdir refuses if the directory still has contents — this is a useful safety feature. Compare this with rm -rf, which deletes everything silently and immediately with no way to recover.

Reading / Reference

  • The Linux Command Line (William Shotts) — Chapters 1–4 (free online).
  • man ls, man mkdir, man chmod — skim the synopsis and common options.
  • tldr cd, tldr chmod — quick practical examples if you have tldr installed.