C Terminal User Input

Question

I was wondering if it's possible to hide or replace what the user of the program write in the terminal.

When the user press a key when the program ask the user to type something like a password, instead of writing the password it write * (ex: password="AAABBB" but in the terminal it shows ****** or just nothing).

It's the same thing as when you write your Windows/Mac password.

thanks a lot !

Ayly_ / C noobies

Not using standard C, but you can do it using OS-specific functions to turn off echoing. — Barmar, May 16 '20 at 05:39
For Linux, look at the `ncurses` library, especially `noecho()` -> https://linux.die.net/man/3/noecho. — RobertS supports Monica Cellio, May 16 '20 at 08:05
Does this answer your question? [Hide password input on terminal](https://stackoverflow.com/questions/6856635/hide-password-input-on-terminal) — serg_zhd, May 16 '20 at 10:27

score 0 · Accepted Answer · answered May 16 '20 at 07:18

You can do this, but it will be something very system specific depending on your operating system and other factors. There are libraries that may do what you want such as "curses", which you could look into. To demonstrate the sort of hackery involved, I wrote something that works on my Ubuntu laptop. Running this may mess up your terminal settings, particularly if you break out mid program. I can use the "reset" command to fix that on Ubuntu or just reopen the terminal window.

#include <termios.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

#define MAX_LENGTH 20

int main()
{
  struct termios t, backup;
  tcgetattr(STDIN_FILENO, &t);
  backup=t;
  cfmakeraw(&t);
  tcsetattr(STDIN_FILENO, TCSANOW, &t);

  char c=0;
  int position = 0;
  char password[MAX_LENGTH+1] = {0};

  while (position<MAX_LENGTH)
  {
    c = getchar();
    if (c<0x20)
      break;

    password[position++] = c;
    putchar ('*');
  }
  tcsetattr(STDIN_FILENO, TCSANOW, &backup);

  printf("\nPassword is : %s\n", password);
}

Thank you !! I will look into it ! And thanks for the advice ! — Ayly_, May 16 '20 at 12:09

C Terminal User Input

1 Answers1