kfscmd.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include <u.h>
#include <libc.h>

void
main(int argc, char *argv[])
{
	char *name, buf[4*1024];
	int fd, n, i, errs;

	name = 0;
	ARGBEGIN{
	case 'n':
		name = ARGF();
		break;
	default:
		fprint(2, "usage: kfscmd [-n server] commands\n");
		exits("usage");
	}ARGEND

	if(name)
		snprint(buf, sizeof buf, "/srv/kfs.%s.cmd", name);
	else
		strcpy(buf, "/srv/kfs.cmd");
	fd = open(buf, ORDWR);
	if(fd < 0){
		fprint(2, "kfscmd: can't open commands file\n");
		exits("commands file");
	}

	errs = 0;
	for(i = 0; i < argc; i++){
		if(write(fd, argv[i], strlen(argv[i])) != strlen(argv[i])){
			fprint(2, "%s: error writing %s: %r", argv0, argv[i]);
			errs++;
			continue;
		}
		for(;;){
			n = read(fd, buf, sizeof buf - 1);
			if(n < 0){
				fprint(2, "%s: error executing %s: %r", argv0, argv[i]);
				errs++;
				break;
			}
			buf[n] = '\0';
			if(strcmp(buf, "done") == 0 || strcmp(buf, "success") == 0)
				break;
			if(strcmp(buf, "unknown command") == 0){
				errs++;
				print("kfscmd: command %s not recognized\n", argv[i]);
				break;
			}
			write(1, buf, n);
		}
	}
	exits(errs ? "errors" : 0);		
}