View, create, and remove files and directories

List and inspect

ls -la shows hidden entries in long format. Useful variations: ls -lh prints human-readable sizes, ls -lt sorts by modification time (newest first), and ls -R lists subdirectories too. stat file.txt shows the full metadata: size, owner, permissions, and access/modify/change times. wc -l file.txt counts lines, which is handy for logs and CSV files.

flowchart LR
  L["ls -la<br/>see what is there"] --> R["cat, less<br/>read contents"]
  R --> M["mkdir -p, touch<br/>create"]
  M --> G["Wildcards *.log<br/>expand first"]
  G --> CHK["ls *.log<br/>preview the match"]
  CHK --> RM["rm -i<br/>remove deliberately"]
  %% step L: List with ls -la to see hidden files, sizes and permissions.
  %% step R: Read small files with cat and long ones with less.
  %% step M: Create directories with mkdir -p and empty files with touch.
  %% step G: The shell expands wildcards before the command runs.
  %% step CHK: Run ls with the same pattern first to see exactly what will match.
  %% step RM: Only then remove, interactively if unsure. There is no recycle bin.

Read file contents

head and tail show 10 lines by default.

Create files and directories

touch empty.txt creates an empty file or updates timestamps. mkdir -p a/b/c creates missing parents. Redirection also creates files: echo "hello" > note.txt overwrites the file, while >> appends to it. Mixing them up is a common way to wipe a config file.

An editor can create a file when it saves. nano shows its shortcuts on screen and is easiest for beginners. In vi, press i to insert text, Esc to return to command mode, :wq to write and quit, and :q! to quit without saving.

Wildcards

The shell expands patterns before the command runs: * matches any characters, ? exactly one, and [0-9] one character from a set. ls *.log therefore receives a list of file names, not the pattern. Run echo rm *.tmp first to preview what a pattern would delete.

Remove deliberately

rmdir removes only empty directories. rm -r project traverses a directory tree; -f suppresses prompts and some errors, so do not add it by habit. rm -i asks before each file and is a safer habit while learning. A normal shell has no trash can for rm.

Before a recursive operation, use pwd and ls to verify the target. Prefer a specific path inside the exercise directory over a broad wildcard.