BESH

Bemly's Shell — a Unix shell written in Rust with libc.

Inspired by lsh.

Features

• Interactive REPL with colored prompt
• Command pipelines (cmd1 | cmd2 | cmd3)
• I/O redirection (>, >>, <, 2>)
• Background jobs (cmd &, jobs)
• Tab completion (commands + file paths)
• Arrow key history navigation
• Line editing (Ctrl+A/E/K/U)
• Environment variable management
• Script execution (.besh files)
• Signal handling (Ctrl+C, Ctrl+Z)
• Job control

Build

git clone https://github.com/Bemly/Besh.git
cd Besh
cargo build --release

The binary is at target/release/besh.

Optionally install to ~/.cargo/bin:

cargo install --path .

Usage

Interactive Mode

./target/release/besh

user@hostname ~> ls -la
user@hostname ~> echo hello world
user@hostname ~> exit

Single Command

./target/release/besh echo "hello world"
./target/release/besh ls -la /tmp

Script Execution

cat > test.besh << 'EOF'
#!/usr/bin/env besh
echo "Running script"
export VAR=value
echo $VAR
ls -la | head -3
EOF

./target/release/besh test.besh

Built-in Commands

Command	Description
cd [path]	Change directory (supports ~)
pwd	Print working directory
echo [args...]	Print to stdout
export VAR=val	Set environment variable
unset VAR	Unset variable
env	Print all environment variables
set	Print all shell variables
history [n]	Show last n commands
jobs	List background jobs
exit / quit / q	Exit shell

Pipes & Redirection

# Pipe
cat file.txt | grep "pattern" | wc -l

# Output redirect
ls -la > listing.txt

# Append
echo "line" >> file.txt

# Input redirect
sort < unsorted.txt

# Stderr redirect
ls /notfound 2> errors.txt

Background Jobs

sleep 60 &
jobs

Tab Completion

• Press Tab to complete commands and file paths
• First word: completes built-in commands and executables from $PATH
• Other words: completes file/directory paths
• Multiple matches are displayed, common prefix is auto-completed

Line Editing

Key	Action
← / →	Move cursor
↑ / ↓	Navigate history
Tab	Complete
Ctrl+A	Move to start
Ctrl+E	Move to end
Ctrl+K	Delete to end of line
Ctrl+U	Delete to start of line
Ctrl+C	Cancel input
Ctrl+D	EOF / exit

Environment Variables

export PATH=/usr/local/bin:$PATH
export EDITOR=vim
echo $HOME
echo $USER

Disable Colors

NO_COLOR=1 ./target/release/besh

CLI Options

besh                    Enter interactive shell
besh <command [args]>   Execute a single command
besh <script.besh>      Execute a script file
besh -h, --help         Show help
besh -v, --version      Show version

Project Structure

src/
├── main.rs          Entry point
├── shell.rs         REPL loop and command execution
├── parser.rs        Command line parsing (pipes, redirects, variables)
├── process.rs       Fork/exec/wait via libc
├── terminal.rs      Raw mode, line editing, tab completion, colors
├── builtin.rs       Built-in command implementations
├── environment.rs   Variable management and prompt formatting
├── history.rs       Command history with file persistence
├── job_control.rs   Background/foreground job management
├── signal.rs        SIGINT, SIGTSTP, SIGCHLD handlers
├── error.rs         Error types
├── common_shell.rs  Legacy stdlib-based shell (fallback)
└── better_truth_tty.rs  Placeholder for future libc shell

API documentation is generated in docs/ via cargo doc.

Dependencies

• libc — POSIX system calls
• dirs — Home directory detection

License

See LICENSE.