diff --git a/common/net.go b/common/net.go
deleted file mode 100644
index a8e4135..0000000
--- a/common/net.go
+++ /dev/null
@@ -1,17 +0,0 @@
-package common
-
-import (
-	"syscall"
-)
-
-func GetFileDescriptor(conn syscall.Conn) (uintptr, error) {
-	rawConn, err := conn.SyscallConn()
-	if err != nil {
-		return 0, err
-	}
-	var rawFd uintptr
-	err = rawConn.Control(func(fd uintptr) {
-		rawFd = fd
-	})
-	return rawFd, err
-}
diff --git a/common/shell.go b/common/shell.go
new file mode 100644
index 0000000..2cd406b
--- /dev/null
+++ b/common/shell.go
@@ -0,0 +1,38 @@
+package common
+
+import (
+	"os"
+	"os/exec"
+)
+
+type Shell struct {
+	*exec.Cmd
+}
+
+func Exec(name string, args ...string) *Shell {
+	command := exec.Command(name, args...)
+	command.Env = os.Environ()
+	return &Shell{command}
+}
+
+func (s *Shell) SetDir(path string) *Shell {
+	s.Dir = path
+	return s
+}
+
+func (s *Shell) Attach() *Shell {
+	s.Stdin = os.Stdin
+	s.Stdout = os.Stderr
+	s.Stderr = os.Stderr
+	return s
+}
+
+func (s *Shell) SetEnv(env []string) *Shell {
+	s.Env = append(os.Environ(), env...)
+	return s
+}
+
+func (s *Shell) Read() (string, error) {
+	output, err := s.CombinedOutput()
+	return string(output), err
+}
diff --git a/common/string.go b/common/string.go
index d7c7bee..38ecd32 100644
--- a/common/string.go
+++ b/common/string.go
@@ -33,3 +33,7 @@ func SubstringBeforeLast(s string, substr string) string {
 	}
 	return s[:index]
 }
+
+func SubstringBetween(s string, after string, before string) string {
+	return SubstringBefore(SubstringAfter(s, after), before)
+}