0-SHELL

Overview

This project is an implementation of the 0-shell subject of the 01-edu curriculum. A Unix Shell built from scratch using Rust.

Built-in Commands

Command	Description	Notable flags / behaviour
echo [args...]	Print arguments to stdout separated by spaces	—
cd [dir]	Change the current working directory. Updates $PWD and $OLDPWD.	no arg / -- → $HOME; - → previous directory ($OLDPWD)
pwd	Print the current working directory	—
ls [options] [path...]	List directory contents	-a show hidden files; -l long format; -F append type indicator
cat [file...]	Concatenate and print files. Reads from stdin when no file is given or - is passed.	—
cp <src> <dest>	Copy a file. Supports copying one file to a destination file or into a directory. Multiple sources require the destination to be a directory.	—
mv <src> <dest>	Move or rename files. Multiple sources require the destination to be a directory.	—
mkdir <dir...>	Create one or more directories	—
rm [options] <path...>	Remove files or directories	-r / -R recursive removal; refuses to remove ., .., and /
clear	Clear the terminal screen	—
exit	Exit the shell with status 0	—

Note: cd, clear, and exit run directly in the parent process. All other commands are executed in a forked child process.

Supported Syntax

The shell parses input following the POSIX Shell Command Language specification.

Quoting

Syntax	Description
'...'	Single quotes — everything inside is treated as a literal string; no expansions occur
"..."	Double quotes — allows $variable, $(...), `...`, and \ escape sequences inside
`...`	Backtick command substitution — executes the enclosed command and substitutes its output

Expansions

Syntax	Description
$VAR	Parameter expansion — replaced with the value of environment variable VAR
$(command)	Command substitution — replaced with the stdout of command
`command`	Command substitution (backtick form) — equivalent to $(command)
~	Tilde expansion — replaced with $HOME (not expanded inside double quotes)

Escape sequences

Syntax	Description
\<char>	Escape the next character, removing its special meaning
\ + newline	Line continuation — the newline is ignored and input reading continues on the next line

Redirections

Operator	Description
< file	Redirect stdin from file
> file	Redirect stdout to file (truncate)
2> file	Redirect stderr to file
&> file	Redirect both stdout and stderr to file

Command separators

Operator	Description
;	Run commands sequentially
newline	Same as ; — separates commands

Installation

Prerequisites: Rust toolchain (edition 2024, i.e. Rust ≥ 1.85)

# Clone the repository
git clone https://github.com/zone01oujda/0-shell.git
cd 0-shell

# Build in release mode
cargo build --release

# The binary will be at
./target/release/shell

Usage

# Run interactively
./target/release/shell

The shell displays a $ prompt and waits for input. Type any supported command and press Enter.

$ echo "Hello, world!"
Hello, world!
$ ls -la
$ cat file.txt
$ cp src.txt dest.txt
$ cd /tmp && pwd
/tmp
$ exit

Alternatively, run directly with Cargo (no separate build step needed):

cargo run --release