atmarp -a writes to file descriptor 0 (STDIN). This
works in most cases of interactive use because shells
open filedescriptor 0 as writable. However, this
requires workarounds when atmarp is used in scripts.
The error message below the write() statement suggests
that this is a typo.
The attached patch does not break workarounds such like
atmarp -a 0>&1 | other-program
-Hilko
Patch against atmarp.c