fileluopen() - opens a file given a logical unit number
FILE *fileluopen(lu, modes)
int lu;
char *modes;
fileluopen() makes an object of type FILE, suitable for use with fileread(),
putc(), etc.
The lu argument is a logical unit number assigned by the kernel
when it opens a file. Logical unit numbers are not usually visible, although
several routines reguire LUs as arguments and fdown() may be used to map a
FILE object to a corresponding LU number.
The modes argument is a string encoding the modes of the file,
just as for fileopen(), except that the 'c' and 't' options are not
allowed.