Initial working shell: bash-for-windows

- Cross-compiled Go-based shell for Windows (PE32+ executable)
- Builtins: cd, pwd, echo, exit, export, source, alias, type
- Coreutils: ls, cat, grep, sort, wc, head, find, cp, mv, rm, mkdir, touch, clear
- Command chaining: &&, ||, ;
- Pipes between builtins and external commands
- Variable expansion (, ) and assignment (NAME=VALUE)
- Tokenizer with single/double quote handling
- Linux and Windows (x86_64) builds via build.sh

cmd/bash/main.go

@@ -0,0 +1,66 @@
+package bash
+
+import (
+    "bufio"
+    "fmt"
+    "os"
+    "strings"
+    "github.com/cametendo/bash-for-windows/internal/shell"
+)
+
+func Run() error {
+    args := os.Args[1:]
+    
+    if len(args) > 0 {
+        if args[0] == "-c" && len(args) > 1 {
+            // Execute a command string
+            return runCommand(strings.Join(args[1:], " "))
+        }
+        // Run a script file
+        return runFile(args[0])
+    }
+    
+    return interactive()
+}
+
+func runCommand(cmd string) error {
+    sh := shell.New()
+    return sh.Execute(cmd)
+}
+
+func runFile(path string) error {
+    data, err := os.ReadFile(path)
+    if err != nil {
+        return fmt.Errorf("%s: %v", path, err)
+    }
+    sh := shell.New()
+    return sh.Execute(string(data))
+}
+
+func interactive() error {
+    sh := shell.New()
+    reader := bufio.NewReader(os.Stdin)
+    
+    fmt.Println("bash-for-windows v1.0.0")
+    
+    for {
+        fmt.Print("bash$ ")
+        input, err := reader.ReadString('\n')
+        if err != nil {
+            break
+        }
+        
+        input = strings.TrimSpace(input)
+        if input == "" {
+            continue
+        }
+        if input == "exit" {
+            break
+        }
+        
+        if err := sh.Execute(input); err != nil {
+            fmt.Fprintf(os.Stderr, "bash: %v\n", err)
+        }
+    }
+    return nil
+}