CLI:使用Go开发命令行应用

var Args []string

package main
import (
 "fmt"
 "os"
)
func main() {
 // Program Name is always the first (implicit) argument
 cmd := os.Args[0]
 fmt.Printf("Program Name: %s\n", cmd)
}

go build
./example1

Program Name: ./example1

package main
import (
 "fmt"
 "os"
)
func main() {
 argCount := len(os.Args[1:])
 fmt.Printf("Total Arguments (excluding program name): %d\n", argCount)
}

package main
import (
 "fmt"
 "os"
)
func main() {
 for i, a := range os.Args[1:] {
 fmt.Printf("Argument %d is %s\n", i+1, a)
 }
}
Running the program with ./example3 -local u=admin --help results in:
Argument 1 is -local
Argument 2 is u=admin
Argument 3 is --help

package main
import (
 "flag"
 "fmt"
)
func main() {
 var port int
 flag.IntVar(&port, "p", 8000, "specify port to use. defaults to 8000.")
 flag.Parse()
 fmt.Printf("port = %d", port)
}

Usage of ./example4:
-p=8000: specify port to use. defaults to 8000.

package main
import (
 "flag"
 "fmt"
)
func main() {
 var port int
 flag.IntVar(&port, "p", 8000, "specify port to use. defaults to 8000.")
 flag.Parse()
 fmt.Printf("port = %d\n", port)
 fmt.Printf("other args: %+v\n", flag.Args())
}

port = 9000
other args: [foo=10 -bar]

package main
import (
 "flag"
 "fmt"
)
func main() {
 var port int
 flag.IntVar(&port, "p", 8000, "specify port to use. defaults to 8000")
 flag.Parse()
 fmt.Printf("port = %d", port)
}

invalid value "foo" for flag -p: strconv.ParseInt: parsing "foo": invalid syntax
Usage of ./example6:
-p=8000: specify port to use. defaults to 8000

package main
import (
 "flag"
 "fmt"
 "os"
)
func main() {
 flag.Usage = func() {
 fmt.Printf("Usage of %s:\n", os.Args[0])
 fmt.Printf(" example7 file1 file2 ...\n")
 flag.PrintDefaults()
 }
 flag.Parse()
}

Usage of ./example7:
example7 file1 file2 ...

package main
import "fmt"
func main() {
 var guessColor string
 const favColor = "blue"
 for {
 fmt.Println("Guess my favorite color:")
 if _, err := fmt.Scanf("%s", &guessColor); err != nil {
 fmt.Printf("%s\n", err)
 return
 }
 if favColor == guessColor {
 fmt.Printf("%q is my favorite color!", favColor)
 return
 }
 fmt.Printf("Sorry, %q is not my favorite color. Guess again.\n", guessColor)
 }
}

package main
import (
 "bufio"
 "fmt"
 "os"
)
func main() {
 scanner := bufio.NewScanner(os.Stdin)
 for scanner.Scan() {
 line := scanner.Text()
 if line == "exit" {
 os.Exit(0)
 }
 fmt.Println(line) // Println will add back the final '\n'
 }
 if err := scanner.Err(); err != nil {
 fmt.Fprintln(os.Stderr, "reading standard input:", err)
 }
}

package main
import (
 "flag"
 "fmt"
 "io"
 "os"
)
func main() {
 flag.Usage = func() {
 fmt.Printf("Usage of %s:\n", os.Args[0])
 fmt.Printf(" cat file1 file2 ...\n")
 flag.PrintDefaults()
 }
 flag.Parse()
 if flag.NArg() == 0 {
 flag.Usage()
 os.Exit(1)
 }
 for _, fn := range flag.Args() {
 f, err := os.Open(fn); 
 if err != nil {
 panic(err)
 }
 _, err = io.Copy(os.Stdout, f)
 if err != nil {
 panic(err)
 }
 }
}

有疑问加站长微信联系(非本文作者)

• 请尽量让自己的回复能够对别人有帮助
• 支持 Markdown 格式, **粗体**、~~删除线~~、`单行代码`
• 支持 @ 本站用户;支持表情(输入 : 提示),见 Emoji cheat sheet
• 图片支持拖拽、截图粘贴等方式上传