upd.c A screen updating program

[utzoo!decvax!duke!harpo!floyd!trb]

Please let me know if you have better ideas. -Andy
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/*
 * cc upd.c -lcurses -ltermcap -o upd
 *
 * upd.c - popen a process and use its output to update the screen
 * argv[1] is popen'ed so quote your command if it's more than one arg.
 * argv[2] is number of seconds to sleep between cycles.
 * Andy Tannenbaum WECo/BTL Whippany, NJ
 */
#include<curses.h>
#include<sys/ioctl.h>
/* 6*1024 is more than 66*80 */
#define BUFSIZE 6*1024
FILE *pp;	/* popen pointer */
char buf[BUFSIZE];
char tbuf[128];
long larg;
main(argc,argv)
int argc; char **argv;
{
	extern char *CD;
	int i,n,sleeptime;

	/* sleep for sleeptime seconds between cycles */
	sleeptime = (argc > 1) ? atol(argv[2]) : 1;
	initscr();

	for(;;){
#ifdef VMUNIX
		/* redraw whole screen when user types a newline */
		/* can be done on UNIX 3.0 too, but I don't */
		ioctl(0,FIONREAD,&larg);
		if(larg != 0L){
			read(0,tbuf,128);
			clear();
		}
#endif
		/* if popen fails we're hurting, so break */
		if((pp=popen(argv[1],"r")) == EOF)exit(1);
		n=fread(buf,1,BUFSIZE,pp);
		buf[n]=0;
		pclose(pp);
		mvaddstr(0,0,buf);
		refresh();
		/* my curses doesn't seem to clear the rest of the screen when
		 * data disappears from it, but it leaves the cursor down
		 * there, so diy */
		printf("%s",CD);

		for(i=0;i<n;i++)buf[n]=0;
		sleep(sleeptime);
	}
}
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