AUSAM/source/S/fd2.c

/*
 * Command to open file descriptor 2 to a file and exec
 * a command.  Four forms:
 *
 * fd2 comd ...		[write on "msg.out"]
 * fd2 -file comd ...	[write on "file"]
 * fd2 --file comd ...	[append to "file"]
 * fd2 -- comd ...		[append to "msg.out"]
 *
 * Additional usage:
 *
 * fd2 + comd ...
 *
 * causes file descriptor 2 to be made same as 1.
 */ 

main(argc, argv)
int argc;
char *argv[];
{
	char *file, app, path[100];
	int fd, start;


	if(argv[1][0] == '+')
	{
		start = 2;
		close(2);
		dup(1);
	}
	else
	{
		if(argv[1][0] != '-')
		{
			file = "\0";
			app = 0;
			start = 1;
		}
		else if(argv[1][1] != '-')
		{
			file = &argv[1][1];
			app = 0;
			start = 2;
		}
		else
		{
			file = &argv[1][2];
			app = 1;
			start = 2;
		}
		if(file[0] == '\0')
			file = "msg.out";

		if(app)
			if((fd = open(file, 1)) < 0)
				app = 0;
			else
				seek(fd, 0, 2);
		if(!app)
			fd = creat(file, 0666);
		if(fd > 2)
		{
			close(2);
			if(dup(fd) != 2)
			{
				write(open("/dev/tty", 1), "bad file descriptor?!?\n", 23);
				exit(1);
			}
			close(fd);
		}
	}

	argv[argc] = 0;
	execc(argv[start], &argv[start]);
	exit(1);
}