Sorry for the spelling in my original mail, I was too tired. Here is how you can reproduce the bug:
root@ec2-instance:~# cat /etc/resolv.conf domain eu-central-1.compute.internal search eu-central-1.compute.internal nameserver 172.31.0.2 root@ec2-instance:~# fallocate -l 1TB /etc/bigfile fallocate: fallocate failed: No space left on device root@ec2-instance:~# dhclient RTNETLINK answers: File exists /sbin/dhclient-script: 54: echo: echo: I/O error /sbin/dhclient-script: 72: echo: echo: I/O error /sbin/dhclient-script: 77: echo: echo: I/O error root@ec2-instance:~# cat /etc/resolv.conf root@ec2-instance:~# rm /etc/bigfile With my patch, dhclient leaves the valid /etc/resolv.conf unmodified instead of making it empty / corrupt. See also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=211261 for a similar problem with dhcp3-client.
