3.1 How can I make my program not echo input?

How can I make my program not echo input, like login does when asking for your password?

There is an easy way, and a slightly harder way:

The easy way, is to use getpass(), which is probably found on almost all Unices. It takes a string to use as a prompt. It will read up to an EOF or newline and returns a pointer to a static area of memory holding the string typed in.

The harder way is to use tcgetattr() and tcsetattr(), both use a struct termios to manipulate the terminal. The following two routines should allow echoing, and non-echoing mode.

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

#include <termios.h>
#include <string.h>

static struct termios stored_settings;

void echo_off(void)
{
    struct termios new_settings;
    tcgetattr(0,&stored_settings);
    new_settings = stored_settings;
    new_settings.c_lflag &= (~ECHO);
    tcsetattr(0,TCSANOW,&new_settings);
    return;
}

void echo_on(void)
{
    tcsetattr(0,TCSANOW,&stored_settings);
    return;
}

Both routines used, are defined by the POSIX standard.

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