A simple date/time program for Wyse terminals

[Jay A. Konigsberg]

The following is a clock that resides in the F8 function key label
(the date goes into F7).

The features are:

1) Clock will sync to change time with the system (to the second).
2) The date is displayed on startup and again when the time is 00:00
   (in case you left your terminal logged in overnight).
3) SIGQUIT (logout) and SIGTERM (kill -15) will clear the clock from
   the labels (too bad about SIGKILL :-( ).
4) The display is done with write(2) to avoid system buffering (using
   puts(3S) or printf(3S) with clock sometimes results in the time
   being displayed across the screen - yes I could have used setbuf(3S)
   and fflush(3S), but I chose write(2) ).
5) The ESC codes can be easily changed and the code recomplied.

The bugs are:

1) No command line options (i.e. you can't turn the date or time off).
2) Only Wyse ESC codes are included.

If there is enough interest (and requests) I'll modify the program
to accept command line options for:

    - [-t[wyse|ansi|vt100] | -c clockESC -d dateESC] -C -D

    (C & D would be clock_only and date_only)

anyway, here is the source:

--------------------------------- cut here -----------------------------------
/*LINTLIBRARY*/
#include        <stdio.h>
#include        <sys/types.h>
#include        <time.h>
#include        <utmp.h>
#include	<signal.h>

#define         F7LABEL "\033z6"        /* esc code for F7 label */
#define         F8LABEL "\033z7"        /* esc code for F8 label */

main()
{
extern	int    	sprintf(),
        	exit();

extern	void	cleanup();

void		date_display(),
		time_display();

unsigned	sleep();
struct	tm      *locatime();
time_t		time();

struct  tm	*timenow;
time_t		clock;

/* initial display of the date and time */
clock = time(&clock);
timenow = localtime((time_t *)&clock);
date_display(timenow);
time_display(timenow);

if ( fork() == 0 )
    {
    signal(SIGINT,  SIG_IGN);
    signal(SIGQUIT, SIG_IGN);
    signal(SIGHUP,  cleanup);
    signal(SIGTERM, cleanup);

    for (;;)
	{
	/* sync the time to change on the exact boundry. Once initilized,
	 * it should never loop more than once or twice */
	do
	    {
	    sleep(1);
	    clock = time(&clock);
	    timenow = localtime((time_t *)&clock);
	    }
	while ( timenow->tm_sec != 0 );

	/* change the date at midnight */
	if ( timenow->tm_hour == 0 && timenow->tm_min == 0 ) 
	    date_display(timenow);

	time_display(timenow);
	sleep (58);
	}
    }
return(0);
}

/*
 * display the date
 */
void	date_display(timenow)
struct	tm	*timenow;
{
char	date_buff[10];

sprintf(date_buff, "%2d/%2d/%2d", timenow->tm_mon+1,
    timenow->tm_mday, timenow->tm_year);
write ( 1, F7LABEL, sizeof(F7LABEL));
write ( 1, date_buff, (unsigned)strlen(date_buff));
}

/*
 * display the time
 */
void	time_display(timenow)
struct	tm	*timenow;
{
char    meridian[3],            /* anti-meridian, post-meridian (am/pm) */
	time_buff[10];

/* setup 12 hour AM/PM notation */
if (timenow->tm_hour == 0)
    {
    timenow->tm_hour = 12;
    meridian[0]='A';
    }
else
    if (timenow->tm_hour == 12)
	meridian[0]='P';
    else
	if (timenow->tm_hour > 12)
	    {
	    timenow->tm_hour -= 12;
	    meridian[0]='P';
	    }
	else /* its in the AM */
	    meridian[0]='A';

meridian[1]='M';
meridian[2]='\0';

if (timenow->tm_min >= 10)
    sprintf (time_buff, "%2d:%d %s", timenow->tm_hour, timenow->tm_min, meridian);
else
    sprintf (time_buff, "%2d:0%1d %s", timenow->tm_hour, timenow->tm_min, meridian);
write(1, F8LABEL, sizeof(F8LABEL));
write(1, time_buff, (unsigned)strlen(time_buff));
}

/*
 * remove the date and time at logout
 */
void	cleanup()
{
write(1, F7LABEL, sizeof(F7LABEL));
write(1, "        ", 8);
write(1, F8LABEL, sizeof(F8LABEL));
write(1, "        ", 8);
exit(0);
}
-- 
-------------------------------------------------------------
Jay @ SAC-UNIX, Sacramento, Ca.   UUCP=...pacbell!sactoh0!jak
If something is worth doing, it's worth doing correctly.