How to programm TTY devices under UNIX platform? Post: 12226

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Top Forums Programming How to programm TTY devices under UNIX platform? Post 12226 by Perderabo on Friday 21st of December 2001 10:57:43 AM

12-21-2001

Administrator Emeritus

There is the old unix way to do this and the new posix way. I wrote a program to put the tty into raw mode using both methods so I could compare them. You should probably understand both techniques since there is a lot of old code out there. But I think the posix revision is a win, so I would suggest going the posix route with new code. I would add the following man pages to your list:

tcattribute(3c)
cfspeed(3C)
tccontrol(3C)

You should use the routines in cfspeed(3C) to change the baud rate.

Here is the sample program that I wrote:

Code:

/*   #define OLD_TERMIO  */

#ifdef __STDC__
#define PROTOTYPICAL
#endif
#ifdef __cplusplus
#define PROTOTYPICAL
#endif

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

#ifdef OLD_TERMIO
#include <termio.h>
#else
#include <termios.h>
#endif

#ifdef PROTOTYPICAL
int main(int argc, char *argv[])
#else
main(argc,argv)
char *argv[];
#endif

{
#ifdef OLD_TERMIO
        struct termio orig,now;
#else
        struct termios orig,now;
#endif
        int c, i, rc, done;
        setvbuf(stdout, NULL, _IONBF ,0);

#ifdef OLD_TERMIO
        ioctl(0, TCGETA, (char *) &orig);
#else
        tcgetattr(0, &orig);
#endif
        now=orig;
        now.c_lflag &= ~(ISIG|ICANON|ECHO);
        now.c_cc[VMIN]=1;
        now.c_cc[VTIME]=2;
#ifdef OLD_TERMIO
        ioctl(0,TCSETA, (char *) &now);
#else
        tcsetattr(0, TCSANOW, &now);
#endif
        done=0;
        while(!done) {
                printf("hit a key: ");
                c=getchar();
                printf(" got a  %03X \n", c);
                done = c=='q';
        }
#ifdef OLD_TERMIO
        ioctl(0,TCSETA, (char *) &orig);
#else
        tcsetattr(0, TCSANOW, &orig);
#endif
        exit(0);
}

Last edited by Perderabo; 01-16-2005 at 02:48 PM.. Reason: remove html which is no longer supported

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LEARN ABOUT CENTOS

systemd-tty-ask-password-agent

SYSTEMD-TTY-ASK-PASSWORD-AGENT(1)			  systemd-tty-ask-password-agent			 SYSTEMD-TTY-ASK-PASSWORD-AGENT(1)

NAME

       systemd-tty-ask-password-agent - List or process pending systemd password requests

SYNOPSIS

       systemd-tty-ask-password-agent [OPTIONS...] [VARIABLE=VALUE...]

DESCRIPTION

       systemd-tty-ask-password-agent is a password agent that handles password requests of the system, for example for hard disk encryption
       passwords or SSL certificate passwords that need to be queried at boot-time or during runtime.

       systemd-tty-ask-password-agent implements the Password Agents Specification[1].

OPTIONS

       The following options are understood:

       -h, --help
	   Prints a short help text and exits.

       --version
	   Prints a short version string and exits.

       --list
	   Lists all currently pending system password requests.

       --query
	   Process all currently pending system password requests by querying the user on the calling TTY.

       --watch
	   Continuously process password requests.

       --wall
	   Forward password requests to wall(1) instead of querying the user on the calling TTY.

       --plymouth
	   Ask question with plymouth(8) instead of querying the user on the calling TTY.

       --console
	   Ask question on /dev/console instead of querying the user on the calling TTY.

EXIT STATUS

       On success, 0 is returned, a non-zero failure code otherwise.

SEE ALSO

       systemd(1), systemctl(1), systemd-ask-password-console.service(8), wall(1), plymouth(8)

NOTES

	1. Password Agents Specification
	   http://www.freedesktop.org/wiki/Software/systemd/PasswordAgents

systemd 208													 SYSTEMD-TTY-ASK-PASSWORD-AGENT(1)

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