feat: Set SSH env vars: SSH_CLIENT, SSH_CONNECTION and SSH_TTY (#3622)

Fixes #2339

pty/start_other.go

@@ -4,6 +4,7 @@
 package pty
 
 import (
+	"fmt"
 	"os/exec"
 	"runtime"
 	"strings"
@@ -18,6 +19,8 @@ func startPty(cmd *exec.Cmd) (PTY, Process, error) {
 	if err != nil {
 		return nil, nil, xerrors.Errorf("open: %w", err)
 	}
+
+	cmd.Env = append(cmd.Env, fmt.Sprintf("SSH_PTY=%s", tty.Name()))
 	cmd.SysProcAttr = &syscall.SysProcAttr{
 		Setsid:  true,
 		Setctty: true,

pty/start_other_test.go

@@ -1,5 +1,4 @@
 //go:build !windows
-// +build !windows
 
 package pty_test
 
@@ -40,4 +39,12 @@ func TestStart(t *testing.T) {
 		require.True(t, xerrors.As(err, &exitErr))
 		assert.NotEqual(t, 0, exitErr.ExitCode())
 	})
+
+	t.Run("SSH_PTY", func(t *testing.T) {
+		t.Parallel()
+		pty, ps := ptytest.Start(t, exec.Command("env"))
+		pty.ExpectMatch("SSH_PTY=/dev/")
+		err := ps.Wait()
+		require.NoError(t, err)
+	})
 }