V7/usr/src/cmd/standalone/cat.c

Find at most related files.
including files from this version of Unix. 
main()
{
	int c, i;
	char buf[50];

	do {
		printf("File: ");
		gets(buf);
		i = open(buf, 0);
	} while (i <= 0);

	while ((c = getc(i)) > 0)
		putchar(c);
	exit(0);
}