root@a1:~# ip link set dev eth0 up
root@a1:~# dhclient eth0 -1 -v -sf "/bin/false"
Internet Systems Consortium DHCP Client 4.3.5
Copyright 2004-2016 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

execve (/bin/false, ...): Permission denied
Listening on LPF/eth0/00:16:3e:05:97:d1
Sending on   LPF/eth0/00:16:3e:05:97:d1
Sending on   Socket/fallback
DHCPREQUEST of 10.75.205.180 on eth0 to 255.255.255.255 port 67 (xid=0x7ec8e465)
DHCPACK of 10.75.205.180 from 10.75.205.1
execve (/bin/false, ...): Permission denied
bound to 10.75.205.180 -- renewal in 1389 seconds.
root@a1:~# echo $?