# bash-for-windows

A bash-compatible shell for Windows, written in Go. Runs natively as a single `.exe` — no WSL, Cygwin, or MSYS2 required.

## Install

1. Download the latest release zip and extract it.
2. Double-click **`install.bat`**.

That's it. The installer:
- Copies `bash.exe` to `%LOCALAPPDATA%\Programs\BashForWindows\`
- Adds it to your user **PATH**
- Registers a **"Bash for Windows"** profile in Windows Terminal so it shows up in the `+` dropdown

```powershell
# Optional flags
.\install.ps1 -InstallDir "C:\Tools\bash"   # custom install path
.\install.ps1 -NoTerminal                   # skip Windows Terminal profile
.\install.ps1 -Uninstall                    # clean removal
```

## Features

### Shell language
- **Control flow** — `if/elif/else/fi`, `for/do/done`, `while/until`
- **Functions** — `name() { ... }` and `function name { ... }`, with `local`/`return`
- **Arithmetic** — `$(( expr ))`, `$((i + 1))`, `$((n % 2))`
- **Command substitution** — `$(cmd)`, including pipelines: `x=$(echo foo | tr a-z A-Z)`
- **Variable expansion** — `$VAR`, `${VAR}`, `${VAR:-default}`, `${VAR:=val}`, `${#VAR}`, `${VAR%suffix}`, `${VAR#prefix}`
- **Glob expansion** — `*.txt`, `src/**`
- **Tilde expansion** — `~/Documents`
- **Quotes** — single `'literal'`, double `"with $vars"`, backslash escapes
- **Inline comments** — `echo hello  # this is ignored`

### I/O
- **Pipelines** — `cmd1 | cmd2 | cmd3`
- **Redirection** — `>`, `>>`, `<`, `2>`, `2>&1`, `&>`
- **Background jobs** — `cmd &`
- **Command chaining** — `&&`, `||`, `;`

### Interactive
- **Command history** with arrow keys (saved to `~/.bash_history`)
- **Tab completion** for commands and file paths
- **Multi-line input** — `if`/`for`/`while`/functions continue on the next line
- **Prompt** shows current directory and last exit code when non-zero

### Built-in commands
| Category | Commands |
|----------|----------|
| Shell | `cd`, `pwd`, `echo`, `exit`, `export`, `set`, `unset`, `source`/`.`, `alias`, `unalias`, `type`, `command`, `which`, `env` |
| Control | `true`, `false`, `test`/`[`, `break`, `continue`, `return`, `shift`, `read`, `printf` |
| Variables | `declare`, `local` |
| Files | `ls`, `cat`, `cp`, `mv`, `rm`, `mkdir`, `touch`, `find`, `stat`, `basename`, `dirname` |
| Text | `grep`, `sed`, `awk`, `sort`, `uniq`, `wc`, `head`, `tail`, `cut`, `tr`, `tee`, `xargs` |
| System | `date`, `sleep`, `clear`, `jobs` |

## Usage

```
bash                  # interactive shell
bash -c 'echo hello'  # run a command string
bash script.sh        # run a script file
bash script.sh arg1   # pass arguments ($1, $2, ...)
```

### Examples

```bash
# Variables and arithmetic
name="World"
echo "Hello $name"
echo $((40 + 2))

# Loops and functions
is_even() {
    if [ $(($1 % 2)) -eq 0 ]; then return 0; else return 1; fi
}
for n in 1 2 3 4 5 6; do
    if is_even $n; then echo "$n is even"; fi
done

# Pipelines and redirection
cat /etc/hosts | grep localhost | wc -l
find . -name "*.go" | xargs grep -l "TODO" > todo_files.txt
echo "result=$(date)" >> log.txt
```

## Build from source

Requires Go 1.21+.

```bash
./build.sh              # builds Linux debug + Windows .exe into build/
./build.sh --release    # also creates release/ folder ready to distribute
```

```bash
# Manual cross-compile
GOOS=windows GOARCH=amd64 CGO_ENABLED=0 go build -ldflags="-s -w" -o bash.exe .
```

## Project layout

```
cmd/bash/            entry point, readline REPL
internal/shell/
  shell.go           Execute, parseBlocks, splitStatements, IsIncomplete
  expand.go          expandWord, tokenize, arithmetic, glob
  exec.go            pipelines, redirections, external commands
  control.go         if/for/while/until, function define/call
  builtins.go        all built-in commands and coreutils
install.ps1          Windows installer (PATH + Windows Terminal profile)
install.bat          double-click wrapper for install.ps1
build.sh             build script
```

## License

MIT