show-ip-before-login.sh

#!/bin/sh
# based on http://offbytwo.com/2008/05/09/show-ip-address-of-vm-as-console-pre-login-message.html

# need to be root to write out these files
if [ `id -u` != 0 ]; then
    echo "Need to run as root.  Maybe use sudo..."
    exit
fi

GET_IP_ADDRESS='/usr/local/bin/get-ip-address'
if [ ! -f $GET_IP_ADDRESS ]; then
    cat >$GET_IP_ADDRESS <<EOF
#!/bin/sh
ip address show dev eth0 | grep "inet " | awk '{ print \$2 }' | awk -F/ '{ print \$1 }'
EOF
    chmod 0755 $GET_IP_ADDRESS
fi


if [ ! -f '/etc/issue-standard' ]; then
    cp /etc/issue /etc/issue-standard
    cat >'/etc/network/if-up.d/show-ip-before-login' <<EOF
#/bin/sh
if [ "\$METHOD" = loopback ]; then
    exit 0
fi

# Only run from ifup.
if [ "\$MODE" != start ]; then
    exit 0
fi

grep -v "^\$" /etc/issue-standard >/etc/issue
echo -n " " >>/etc/issue
$GET_IP_ADDRESS >>/etc/issue
echo "" >> /etc/issue
EOF
    chmod 0755 /etc/network/if-up.d/show-ip-before-login
fi