From bf03439c73fc0eab07ef8055a22c715238d26e76 Mon Sep 17 00:00:00 2001
From: Jeff Carr <jcarr@wit.com>
Date: Mon, 9 Aug 2021 01:26:17 -0500
Subject: [PATCH] DEMO: example shell code

Signed-off-by: Jeff Carr <jcarr@wit.com>
---
 example-shell/bash.go | 59 +++++++++++++++++++++++++++++++++++++++++++
 example-shell/env.go  | 59 +++++++++++++++++++++++++++++++++++++++++++
 example-shell/ls.go   | 59 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 177 insertions(+)
 create mode 100644 example-shell/bash.go
 create mode 100644 example-shell/env.go
 create mode 100644 example-shell/ls.go

diff --git a/example-shell/bash.go b/example-shell/bash.go
new file mode 100644
index 0000000..e51b20e
--- /dev/null
+++ b/example-shell/bash.go
@@ -0,0 +1,59 @@
+package main
+
+import (
+        "io"
+        "log"
+        "os"
+        "os/exec"
+        "os/signal"
+        "syscall"
+
+        "github.com/creack/pty"
+        "golang.org/x/term"
+)
+
+func test() error {
+        // Create arbitrary command.
+        c := exec.Command("bash")
+
+        // Start the command with a pty.
+        ptmx, err := pty.Start(c)
+        if err != nil {
+                return err
+        }
+        // Make sure to close the pty at the end.
+        defer func() { _ = ptmx.Close() }() // Best effort.
+
+        // Handle pty size.
+        ch := make(chan os.Signal, 1)
+        signal.Notify(ch, syscall.SIGWINCH)
+        go func() {
+                for range ch {
+                        if err := pty.InheritSize(os.Stdin, ptmx); err != nil {
+                                log.Printf("error resizing pty: %s", err)
+                        }
+                }
+        }()
+        ch <- syscall.SIGWINCH // Initial resize.
+        defer func() { signal.Stop(ch); close(ch) }() // Cleanup signals when done.
+
+        // Set stdin in raw mode.
+        oldState, err := term.MakeRaw(int(os.Stdin.Fd()))
+        if err != nil {
+                panic(err)
+        }
+        defer func() { _ = term.Restore(int(os.Stdin.Fd()), oldState) }() // Best effort.
+
+        // Copy stdin to the pty and the pty to stdout.
+        // NOTE: The goroutine will keep reading until the next keystroke before returning.
+        go func() { _, _ = io.Copy(ptmx, os.Stdin) }()
+        _, _ = io.Copy(os.Stdout, ptmx)
+
+        return nil
+}
+
+func main() {
+        if err := test(); err != nil {
+                log.Fatal(err)
+        }
+}
diff --git a/example-shell/env.go b/example-shell/env.go
new file mode 100644
index 0000000..d8f52d5
--- /dev/null
+++ b/example-shell/env.go
@@ -0,0 +1,59 @@
+package main
+
+import (
+        "io"
+        "log"
+        "os"
+        "os/exec"
+        "os/signal"
+        "syscall"
+
+        "github.com/creack/pty"
+        "golang.org/x/term"
+)
+
+func test() error {
+        // Create arbitrary command.
+        c := exec.Command("env")
+
+        // Start the command with a pty.
+        ptmx, err := pty.Start(c)
+        if err != nil {
+                return err
+        }
+        // Make sure to close the pty at the end.
+        defer func() { _ = ptmx.Close() }() // Best effort.
+
+        // Handle pty size.
+        ch := make(chan os.Signal, 1)
+        signal.Notify(ch, syscall.SIGWINCH)
+        go func() {
+                for range ch {
+                        if err := pty.InheritSize(os.Stdin, ptmx); err != nil {
+                                log.Printf("error resizing pty: %s", err)
+                        }
+                }
+        }()
+        ch <- syscall.SIGWINCH // Initial resize.
+        defer func() { signal.Stop(ch); close(ch) }() // Cleanup signals when done.
+
+        // Set stdin in raw mode.
+        oldState, err := term.MakeRaw(int(os.Stdin.Fd()))
+        if err != nil {
+                panic(err)
+        }
+        defer func() { _ = term.Restore(int(os.Stdin.Fd()), oldState) }() // Best effort.
+
+        // Copy stdin to the pty and the pty to stdout.
+        // NOTE: The goroutine will keep reading until the next keystroke before returning.
+        go func() { _, _ = io.Copy(ptmx, os.Stdin) }()
+        _, _ = io.Copy(os.Stdout, ptmx)
+
+        return nil
+}
+
+func main() {
+        if err := test(); err != nil {
+                log.Fatal(err)
+        }
+}
diff --git a/example-shell/ls.go b/example-shell/ls.go
new file mode 100644
index 0000000..9cf4ab1
--- /dev/null
+++ b/example-shell/ls.go
@@ -0,0 +1,59 @@
+package main
+
+import (
+        "io"
+        "log"
+        "os"
+        "os/exec"
+        "os/signal"
+        "syscall"
+
+        "github.com/creack/pty"
+        "golang.org/x/term"
+)
+
+func test() error {
+        // Create arbitrary command.
+        c := exec.Command("ls", "-al", "/home")
+
+        // Start the command with a pty.
+        ptmx, err := pty.Start(c)
+        if err != nil {
+                return err
+        }
+        // Make sure to close the pty at the end.
+        defer func() { _ = ptmx.Close() }() // Best effort.
+
+        // Handle pty size.
+        ch := make(chan os.Signal, 1)
+        signal.Notify(ch, syscall.SIGWINCH)
+        go func() {
+                for range ch {
+                        if err := pty.InheritSize(os.Stdin, ptmx); err != nil {
+                                log.Printf("error resizing pty: %s", err)
+                        }
+                }
+        }()
+        ch <- syscall.SIGWINCH // Initial resize.
+        defer func() { signal.Stop(ch); close(ch) }() // Cleanup signals when done.
+
+        // Set stdin in raw mode.
+        oldState, err := term.MakeRaw(int(os.Stdin.Fd()))
+        if err != nil {
+                panic(err)
+        }
+        defer func() { _ = term.Restore(int(os.Stdin.Fd()), oldState) }() // Best effort.
+
+        // Copy stdin to the pty and the pty to stdout.
+        // NOTE: The goroutine will keep reading until the next keystroke before returning.
+        go func() { _, _ = io.Copy(ptmx, os.Stdin) }()
+        _, _ = io.Copy(os.Stdout, ptmx)
+
+        return nil
+}
+
+func main() {
+        if err := test(); err != nil {
+                log.Fatal(err)
+        }
+}