🐚 Chibioi's Shell

A custom UNIX shell implemented in both C and Rust, supporting built-in commands, external program execution, and single-pipe piping.

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Features

• Interactive REPL loop with a > prompt
• Built-in commands: cd, ls, help, exit
• External command execution via fork/execvp (C) and std::process::Command (Rust)
• Single pipe (|) support between two commands
• Inline comment stripping — anything after # on a line is ignored
• Dynamic input buffer that grows as needed (C implementation)

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Project Structure

.
├── C
│   ├── Makefile
│   ├── my_shell
│   └── shell.c
├── docs
│   └── README.md
└── Rust
    ├── Cargo.lock
    ├── Cargo.toml
    ├── src
    │   └── main.rs
    └── target

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Getting Started

Prerequisites

• C build: GCC or Clang
• Rust build: Rust toolchain (rustc + cargo) — install via rustup

Building

# Build the C version
make

# Or build the Rust version
cargo build --release

Running

# C version
./shell

# Rust version
./target/release/<project-name>

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Built-in Commands

Command	Description
cd <path>	Change the current working directory
ls [path]	List directory contents (defaults to .)
help	Display help and list all built-in commands
exit	Exit the shell

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Usage Examples

# Navigate directories
> cd /home/user/projects

# List files
> ls
> ls /etc

# Pipe output between commands
> ls | grep main

# Run any external program
> echo "Hello, World!"
> cat shell.c

# Inline comments are ignored
> echo hello  # this part is ignored
hello

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Implementation Notes

C (shell.c)

• Uses fork() + execvp() for process creation and execution
• Manual memory management with malloc/realloc/free
• Pipe support via pipe(), dup2(), and two fork() calls
• Input buffer doubles in size when capacity is exceeded
• strtok_r used for thread-safe line tokenization

Rust (main.rs)

• Uses std::process::Command for spawning child processes
• Pipe support via Stdio::piped() and .stdout.take()
• Leverages Rust's ownership model — no manual memory management needed
• env::set_current_dir for cd, fs::read_dir for ls
• Pattern matching replaces the C-style strcmp loop for built-in dispatch

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Known Limitations

• Only a single | pipe is supported per command (no chaining)
• No support for I/O redirection (>, <, >>)
• No background process execution (&)
• No command history or tab completion

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