Little refactor on command creation

execext/exec.go

@@ -0,0 +1,22 @@
+package execext
+
+import (
+	"os/exec"
+)
+
+var (
+	// ShPath is path to "sh" command
+	ShPath string
+	// ShExists is true if "sh" command is available on the system
+	ShExists bool
+)
+
+func init() {
+	var err error
+	ShPath, err = exec.LookPath("sh")
+	ShExists = err == nil
+}
+
+func newShCommand(c string) *exec.Cmd {
+	return exec.Command(ShPath, "-c", c)
+}

execext/exec_other.go

@@ -0,0 +1,13 @@
+// +build !windows
+
+package execext
+
+import (
+	"os/exec"
+)
+
+// NewCommand returns a new command that runs on "sh" is available or on "cmd"
+// otherwise on Windows
+func NewCommand(c string) *exec.Cmd {
+	return newShCommand(c)
+}

execext/exec_win.go

@@ -0,0 +1,20 @@
+// +build windows
+
+package execext
+
+import (
+	"os/exec"
+)
+
+// NewCommand returns a new command that runs on "sh" is available or on "cmd"
+// otherwise on Windows
+func NewCommand(c string) *exec.Cmd {
+	if ShExists {
+		return newShCommand(c)
+	}
+	return newCmdCommand(c)
+}
+
+func newCmdCommand(c string) {
+	return exec.Command("cmd", "/C", c)
+}