LinuxCLI — Linux Command Line Simulator

Overview

LinuxCLI is a Java-based simulation of a Linux command line interface demonstrating how real command-line interpreters parse user input, manipulate the file system, and handle output redirection.

The project is built around three main classes:

1. Parser – Parses user input and extracts commands with their arguments.
2. Terminal – Implements all command functionalities and manages file operations.
3. Main – The entry point of the program that initializes and runs the CLI session.

It replicates the behavior of core Linux shell commands

Command	Description
pwd	Displays the current working directory.
cd	Changes the current directory. Supports .., relative, and absolute paths.
ls	Lists directory contents sorted alphabetically.
mkdir	Creates one or more directories (absolute or relative paths).
rmdir	Removes empty directories or all empty directories in the current folder using rmdir *.
touch	Creates a new file (absolute or relative path).
rm	Deletes a single file.
cp	Copies a file to another file.
cp -r	Recursively copies directories and their contents.
cat	Displays the contents of one file, or concatenates two files.
wc	Counts the number of lines, words, and characters in a file.
echo	Prints text or messages to the console (supports output redirection with > or >>).
>	Redirects output to a file (creates or overwrites).
>>	Appends output to a file if it exists.
zip	Compresses one or more files or directories into a ZIP archive. Supports -r for recursive compression.
unzip	Extracts ZIP archives into the current or specified directory using -d.
exit	Safely closes the CLI session.

Error handling ensures invalid commands or parameters do not crash the program.

Together, they create a compact, fully functional shell-like environment that mimics the structure and flow of real Linux terminals.

Project Structure

src/
│
├── Parser.java      # Parses and tokenizes user input
├── Terminal.java    # Implements all command logic
└── Main.java        # Runs the main CLI loop

Example Session

USER@CLI:~$ mkdir folder1
USER@CLI:~$ cd folder1
USER@CLI:~/folder1$ touch fileA.txt
USER@CLI:~/folder1$ echo Hello World > fileA.txt
USER@CLI:~/folder1$ echo This is a second line >> fileA.txt
USER@CLI:~/folder1$ cat fileA.txt
Hello World
This is a second line
USER@CLI:~/folder1$ wc fileA.txt
2 7 32 fileA.txt
USER@CLI:~/folder1$ cd ..
USER@CLI:~$ zip -r archive.zip folder1
USER@CLI:~$ unzip archive.zip -d extracted
USER@CLI:~$ exit
CLI session closed by user

License

This project is licensed under the MIT License.

---