当一个服务需要在运行时对一些简要的后台指令做出响应时，regcmd 提供一种监听 stdin 的指令信息并执行代码的简要操作逻辑。您可以注册自己的指令和操作，regcmd 会自动生成对应的 help 指令，之后监听指定的数据流 （如 stdin）即可解析指令。
package main
import (
"context"
"fmt"
"github.com/minoic/regcmd"
"math/rand"
"os"
"time"
)
func main() {
regcmd.ShouldRegister("show", []string{"say hello world"}, func(ctx *regcmd.Context, args []string) {
fmt.Println("hello world")
})
regcmd.ShouldRegister("show (.*)", []string{"user", "say hello to the given user name"}, func(ctx *regcmd.Context, args []string) {
fmt.Println("hello", args[0])
})
err := regcmd.Register("sleep", []string{}, func(ctx *regcmd.Context, args []string) {
id := rand.Int()
fmt.Println(id, "starts to sleep")
time.Sleep(5 * time.Second)
fmt.Println(id, "sleeped 5 seconds")
})
if err != nil {
fmt.Println(err)
}
regcmd.Listen(os.Stdin, regcmd.WithPoolSize(2),
regcmd.WithLoggerFunc(func(s string) {
fmt.Println("log: ", s)
}),
regcmd.WithContextGeneration(func() context.Context {
return context.Background()
}),
)
}运行以上代码，可以经由控制台完成一些简单的指令，结果如下图。
s
log: Invalid command: s **Type <help> for commands help
help
log: ---- all commands help ----
log: show <user> // say hello to the given user name
log: show help // To get this help
log: show // say hello world
log: help // To get all commands help
log: sleep help // To get this help
log: sleep
show
hello
sleep
9410 starts to sleep
sleep
3551 starts to sleep
sleep
9410 sleeped 5 seconds
5821 starts to sleep
3551 sleeped 5 seconds
5821 sleeped 5 seconds