This is indeed a regression in lxc-attach. Until 2.0.0~rc1 this DTRT:
$ sudo lxc-attach -n adt-virt-lxc-lbmmpf -- sh -c 'echo ERR>&2' >/dev/null ERR
but not any more with rc5: $ sudo lxc-attach -n a -- sh -c 'echo ERR>&2' >/dev/null # (no output)
This is indeed a regression in lxc-attach. Until 2.0.0~rc1 this DTRT:
$ sudo lxc-attach -n adt-virt-lxc-lbmmpf -- sh -c 'echo ERR>&2' >/dev/null
ERR
but not any more with rc5:
$ sudo lxc-attach -n a -- sh -c 'echo ERR>&2' >/dev/null
# (no output)