/* setecho.c
 *   usage:  setecho [y|n]
 *   shows:  how to read, change, reset tty attributes
 */

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

#define  oops(s,x) { perror(s); exit(x); }

main(int ac, char *av[])
{
        struct termios info;

        if ( ac == 1 ) 
		exit(0);

        if ( tcgetattr(0,&info) == -1 )          /* get attribs   */
		oops("tcgettattr", 1);

        if ( av[1][0] == 'y' )
                info.c_lflag |= ECHO ;          /* turn on bit    */
        else
                info.c_lflag &= ~ECHO ;         /* turn off bit   */

        if ( tcsetattr(0,TCSANOW,&info) == -1 ) /* set attribs    */
               oops("tcsetattr",2);
}