use cmd.exe as default shell on windows

Mentioned in #12.

app.go

@@ -140,7 +140,11 @@ func (app *app) runShell(s string, args []string, wait bool, async bool) {
 		s = fmt.Sprintf("IFS='%s'; %s", gOpts.ifs, s)
 	}
 
-	args = append([]string{"-c", s, "--"}, args...)
+	if runtime.GOOS == "windows" {
+		args = append([]string{"/c", s}, args...)
+	} else {
+		args = append([]string{"-c", s, "--"}, args...)
+	}
 
 	cmd := exec.Command(gOpts.shell, args...)
 

opts.go

@@ -1,6 +1,9 @@
 package main
 
-import "time"
+import (
+	"runtime"
+	"time"
+)
 
 var gOpts struct {
 	dircounts  bool
@@ -40,7 +43,11 @@ func init() {
 	gOpts.scrolloff = 0
 	gOpts.tabstop = 8
 	gOpts.filesep = ":"
-	gOpts.shell = "/bin/sh"
+	if runtime.GOOS == "windows" {
+		gOpts.shell = "cmd"
+	} else {
+		gOpts.shell = "/bin/sh"
+	}
 	gOpts.sortby = "natural"
 	gOpts.timefmt = time.ANSIC
 	gOpts.ratios = []int{1, 2, 3}