#! /bin/sh

pid=$1

# assumes Linux
# also assumes that the process has fd 0, 1, and 2 open.
gdb /proc/$pid/exe $pid <<EOF
call close(0)
call close(1)
call close(2)
call open("/dev/null", 0)
call open("/dev/null", 1)
call open("/dev/null", 1)
call chdir("/")
detach
EOF