If you manage old Linux machines it might be after the update either due to update mess or because of old system administrators which manually included the UUID to the config forgot to include it in the present network configuration in /etc/sysconfig/networking-scripts/ifcfg-* Universally Unique IDentifier (UUID)128-bit label I used a small one liner after listing all the existing configured LAN interfaces reported from iproute2 network stack with ip command. As this might be useful to someone out there here is the simple command that returns a number of commands to later just copy paste to console once verified there are no duplicates of the UUID already in the present server configuration with grep.
In overall to correct the configs and reload the network with the proper UUIDs here is what I had to do:
# grep -rli UUID /etc/sysconfig/network-scripts/ifcfg-*
No output from the recursive grep means UUIDs are not present on any existing interface, so we can step further check all the existing machines network ifaces and generate the missing UUIDs with uuidgen command
# ip a s |grep -Ei ': <'|sed -e 's#:##g' |grep -v '.' |awk '{ print $2 }'
ifcfg-venet0
ifcfg-eth0
ifcfg-eth1
ifcfg-eth2
ifcfg-eth3
I've stumbled on that case on some legacy Linux inherited from other people sysadmins and in order to place the correct
# for i in $(ip a s |grep -Ei ': <'|sed -e 's#:##g' |grep -v '.' |awk '{ print $2 }'); do echo "echo UUID=$(uuidgen $i)"" >> ifcfg-$i"; done|grep -v '-lo'
echo UUID=26819d24-9452-4431-a9ca-176d87492b75 >> ifcfg-venet0
echo UUID=3c7e8848-0232-436f-a52a-46db9a03eb33 >> ifcfg-eth0
echo UUID=1fc0454d-bf23-417d-b960-571fc04754d2 >> ifcfg-eth1
echo UUID=5793c1e5-4481-4f09-967e-2cceda85c35f >> ifcfg-eth2
echo UUID=65fdcaf6-d271-4845-a8f1-0ec478c375d1 >> ifcfg-eth3
As you can see I exclude the loopback interface -lo from the ouput as it is not necessery to have UUID for it.
That's all folks problem solved. Enjoy
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Tags: awk, command, grep, howto, ip, linux?, sysadmins, sysconfig, update, UUID
