all: add cmd/gclip

Author: changkun

Dockerfile

@@ -5,8 +5,7 @@
 # Written by Changkun Ou <changkun.de>
 
 FROM golang:1.16rc1
-RUN apt-get update \
-    && DEBIAN_FRONTEND=noninteractive apt-get install -y \
+RUN apt-get update && apt-get install -y \
       xvfb libx11-dev \
     && apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 WORKDIR /app

README.md

@@ -8,10 +8,11 @@ import "golang.design/x/clipboard"
 
 ## Dependency
 
-- Linux users: `apt install -y libx11-dev`
-- macOS users: no dependency
+- Linux users: require X: `apt install -y libx11-dev` or `xorg-dev`
+- macOS users: require Cgo, no dependency
+- Windows users: unsupported yet
 
-## Usage
+## API Usage
 
 ```go
 // write texts to the clipboard
@@ -27,6 +28,35 @@ clipboard.Write(clipboard.MIMEImage, []byte("image data"))
 clipboard.Read(clipboard.MIMEImage)
 ```
 
+## Command Usage
+
+```sh
+go install golang.design/x/clipboard/cmd/gclip@latest
+```
+
+```
+gclip is a command that provides clipboard interaction.
+
+usage: gclip [-copy|-paste] [-f <file>]
+
+options:
+  -copy
+        copy data to clipboard
+  -f string
+        source or destination to a given file path
+  -paste
+        paste data from clipboard
+
+examples:
+gclip -paste                    paste from clipboard and prints the content
+gclip -paste -f x.txt           paste from clipboard and save as text to x.txt
+gclip -paste -f x.png           paste from clipboard and save as image to x.png
+
+cat x.txt | gclip -copy         copy content from x.txt to clipboard
+gclip -copy -f x.txt            copy content from x.txt to clipboard
+gclip -copy -f x.png            copy x.png as image data to clipboard
+```
+
 ## Notes
 
 To put image data to system clipboard, you could:

cmd/gclip/main.go

@@ -0,0 +1,128 @@
+// Copyright 2021 The golang.design Initiative authors.
+// All rights reserved. Use of this source code is governed
+// by a GNU GPL-3 license that can be found in the LICENSE file.
+//
+// Written by Changkun Ou <changkun.de>
+
+package main // go install golang.design/x/clipboard/cmd/gclip@latest
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	"golang.design/x/clipboard"
+)
+
+func usage() {
+	fmt.Fprintf(os.Stderr, `gclip is a command that provides clipboard interaction.
+
+usage: gclip [-copy|-paste] [-f <file>]
+
+options:
+`)
+	flag.PrintDefaults()
+	fmt.Fprintf(os.Stderr, `
+examples:
+gclip -paste                    paste from clipboard and prints the content
+gclip -paste -f x.txt           paste from clipboard and save as text to x.txt
+gclip -paste -f x.png           paste from clipboard and save as image to x.png
+
+cat x.txt | gclip -copy         copy content from x.txt to clipboard
+gclip -copy -f x.txt            copy content from x.txt to clipboard
+gclip -copy -f x.png            copy x.png as image data to clipboard
+`)
+	os.Exit(2)
+}
+
+var (
+	in   = flag.Bool("copy", false, "copy data to clipboard")
+	out  = flag.Bool("paste", false, "paste data from clipboard")
+	file = flag.String("f", "", "source or destination to a given file path")
+)
+
+var (
+	errUnsupported = errors.New("unsupported MIME format")
+)
+
+func main() {
+	flag.Usage = usage
+	flag.Parse()
+	if *out {
+		if err := pst(); err != nil {
+			usage()
+		}
+		return
+	}
+	if *in {
+		if err := cpy(); err != nil {
+			usage()
+		}
+		return
+	}
+	usage()
+}
+
+func cpy() error {
+	t := clipboard.MIMEText
+	ext := filepath.Ext(*file)
+
+	switch ext {
+	case ".png":
+		t = clipboard.MIMEImage
+	case ".txt":
+		fallthrough
+	default:
+		t = clipboard.MIMEText
+	}
+
+	var (
+		b   []byte
+		err error
+	)
+	if *file != "" {
+		b, err = os.ReadFile(*file)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "failed to read given file: %v", err)
+			return err
+		}
+	} else {
+		b, err = io.ReadAll(os.Stdin)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "failed to read from stdin: %v", err)
+			return err
+		}
+	}
+
+	clipboard.Write(t, b)
+	return nil
+}
+
+func pst() (err error) {
+	var b []byte
+
+	b = clipboard.Read(clipboard.MIMEText)
+	if b == nil {
+		b = clipboard.Read(clipboard.MIMEImage)
+	}
+
+	if *file != "" && b != nil {
+		err = os.WriteFile(*file, b, os.ModePerm)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "failed to write data to file %s: %v", *file, err)
+		}
+		return err
+	}
+
+	for len(b) > 0 {
+		n, err := os.Stdout.Write(b)
+		if err != nil {
+			return err
+		}
+		b = b[n:]
+	}
+	return nil
+}