是否可以通过扫描从控制台读取而不回显字符? [英] Is it possible to read from the console with scan without echoing the characters?

问题描述

这是一个示例函数:

    passwordEntry <- function() {
            cat("Enter your password: ")
            pwd <- scan(n=1, what=character(), quiet=TRUE)
            invisible(pwd)
    }

并测试功能:

    >   passwordEntry()
    Enter your password: 
    1: test
    > 

有没有一种方法可以禁止用户输入?还是用其他字符替换它?我已经编写了一个tcl/tk函数来提示用户输入密码，但是它在我们的Linux服务器上不起作用.

Is there a way to suppress what the user types? Or replace it with some other character? I have written a tcl/tk function to prompt the user for a password but it doesn't work on our Linux server.

以下是Paul链接中的一个示例.这在Linux或Windows上均不起作用(后者可能是因为我没有合适的C编译器，因此我们将对此进行研究).

Here is an example from Paul's link below. This does not work either on Linux or Windows (the latter probably because I don't have a proper C compiler so will look into that).

getkey3.c

    #include <stdio.h>
    #include <termios.h>
    #include <unistd.h>
    void mygetch ( int *ch ) 
    {
            struct termios oldt, newt;
            tcgetattr ( STDIN_FILENO, &oldt );
            newt = oldt;
            newt.c_lflag &= ~( ICANON | ECHO );
            tcsetattr ( STDIN_FILENO, TCSANOW, &newt );
            *ch = getchar();
            tcsetattr ( STDIN_FILENO, TCSANOW, &oldt );
            return;
    }

还有我的test.r脚本:

    system('R CMD SHLIB getkey3.c')
    dyn.load("getkey3.so")
    .C("mygetch",as.integer(0))
    dyn.unload("getkey3.so")

我明白了:

    > .C("mygetch",as.integer(0))
    [[1]]
    [1] -1

推荐答案

这篇文章介绍了如何读取各个按键:

This post covers how to read individual keystrokes:

检测单个击键

可接受的答案使用一小段C代码返回单个击键.然后，您可以捕获密码的击键，并且不向用户或*发出任何回声.

The accepted answer uses a small piece of C code that returns individual keystrokes. You can then capture the keystrokes for your password and echo nothing to the user or maybe a *.

这篇关于是否可以通过扫描从控制台读取而不回显字符?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！