gosh - Go Shell

A lightweight, interactive POSIX-like shell written in Go. Built as part of the CodeCrafters "Build Your Own Shell" challenge, then refactored into a standalone project.

Features

• Interactive REPL with readline support (line editing, history navigation)
• Builtin commands: echo, exit, type, pwd, cd, history
• External command execution via PATH lookup
• Pipelines: chain commands with |
• I/O redirection: >, >>, 2>, 2>> (stdout and stderr)
• Quote handling: single quotes, double quotes with escape sequences
• Tab completion for builtins and executables
• Persistent command history via HISTFILE environment variable

Requirements

• Go 1.25+

Installation

# Clone the repository
git clone https://github.com/mtsakharov/go-shell.git
cd go-shell

# Build
make build

# Or install directly
go install ./cmd/gosh

Usage

# Run the shell
./gosh

# Or with history persistence
HISTFILE=~/.gosh_history ./gosh

Builtin Commands

Command	Description
echo [args...]	Print arguments to stdout
exit	Exit the shell
type <command>	Show whether a command is a builtin or its path
pwd	Print the current working directory
cd [dir]	Change directory (defaults to $HOME)
history [n]	Show command history (last n entries)
history -r <file>	Read history from file
history -w <file>	Write history to file
history -a <file>	Append new history entries to file

Pipelines

$ echo hello | cat
hello
$ ls -la | grep go | head -5

Redirection

$ echo hello > output.txt       # truncate stdout to file
$ echo world >> output.txt      # append stdout to file
$ cmd 2> errors.log             # redirect stderr to file
$ cmd 2>> errors.log            # append stderr to file

Project Structure

go-shell/
├── cmd/
│   └── gosh/
│       └── main.go             # Entry point
├── internal/
│   └── shell/
│       ├── shell.go            # Shell struct, REPL loop, history
│       ├── builtins.go         # Builtin command implementations
│       ├── exec.go             # Command dispatch and pipeline execution
│       ├── parse.go            # Argument parsing and pipeline splitting
│       ├── path.go             # PATH lookup utilities
│       ├── redirect.go         # I/O redirection handling
│       └── complete.go         # Tab completion
├── docs/
│   └── architecture.md         # Architecture documentation
├── Makefile
├── go.mod
├── go.sum
├── README.md
└── CONTRIBUTING.md

Development

make build   # Build the binary
make run     # Build and run
make test    # Run tests
make lint    # Run go vet
make clean   # Remove build artifacts

License

MIT