bug#25029: shuf generates “Bad file descriptor” error on nfs but only when run as a background process

[Paul Eggert]

Pádraig Brady wrote:
> Actually the minimum reproducer is:
>
>   $ shuf /dev/null 0>&-
>   shuf: read error: Bad file descriptor

Ouch. Isn't that a bug in glibc freopen? It shouldn't fail with errno==EINVAL 
merely because stdin doesn't have a valid file descriptor. If so, we should fix 
the Gnulib freopen module to work around the bug. If not, I suppose we can fix 
this in freopen-safer.