Systemctl 2019 on Ubuntu19.04

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Systemctl 2019 on Ubuntu19.04

Go to the network directory
>cd /etc/netplan

>sudo vi 50-cloud-init.yaml
> cat /etc/netplan/50-cloud-init.yaml
# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    ethernets:
        enp0s3:
            dhcp4: true
        enp0s8:
            dhcp4: no
            addresses: [192.168.56.104/24]
            gateway4: 192.168.56.0
            nameservers:
                    addresses: [8.8.8.8, 8.8.4.4]
    version: 2

>sudo netplan apply

Check Network
> ifconfig
enp0s3: flags=4163  mtu 1500
        inet 10.0.2.15  netmask 255.255.255.0  broadcast 10.0.2.255
        inet6 fe80::a00:27ff:fec7:ba2  prefixlen 64  scopeid 0x20
        ether 08:00:27:c7:0b:a2  txqueuelen 1000  (Ethernet)
        RX packets 28  bytes 6966 (6.9 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 39  bytes 4677 (4.6 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
enp0s8: flags=4163  mtu 1500
        inet 192.168.56.104  netmask 255.255.255.0  broadcast 192.168.56.255
        inet6 fe80::a00:27ff:febc:6cd8  prefixlen 64  scopeid 0x20
        ether 08:00:27:bc:6c:d8  txqueuelen 1000  (Ethernet)
        RX packets 109  bytes 13904 (13.9 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 79  bytes 11730 (11.7 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
lo: flags=73  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 88  bytes 6700 (6.7 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 88  bytes 6700 (6.7 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Some Basic Commands
Check the status of system
> systemctl status

List all the units
> systemctl list-units

Check the failed units
> systemctl --failed

The files is under
/usr/lib/systemd/system
/etc/systemd/system

Check all the services
> systemctl list-unit-files

Install the service on newly machine
>sudo apt-get install keepalived

Check version
>keepalived -version
Keepalived v2.0.10 (11/12,2018)
Copyright(C) 2001-2018 Alexandre Cassen,
Built with kernel headers for Linux 4.19.5
Running on Linux 5.0.0-20-generic #21-Ubuntu SMP Mon Jun 24 09:32:09 UTC 2019

Check the Service
> systemctl list-unit-files | grep keepalived
keepalived.service                     enabled

On my ubuntu-master, when I checked
> systemctl list-unit-files | grep keepalived
snap-keepalived-448.mount              enabled       
keepalived.service                     masked        
snap.keepalived.daemon.service         enabled

> systemctl list-unit-files | grep keepalived
snap-keepalived-448.mount                  enabled       
keepalived.service                         masked        
snap.keepalived.daemon.service             enabled

Check the status on the second machine
> ps -ef | grep keepalived
root       940     1  0 20:10 ?        00:00:00 /snap/keepalived/448/usr/sbin/keepalived-500
root       941   940  0 20:10 ?        00:00:00 /snap/keepalived/448/usr/sbin/keepalived-500

Disable others
> systemctl disable snap-keepalived-448.mount
> systemctl disable snap.keepalived.daemon.service

Unmask my service
> sudo systemctl unmask keepalived.service

Enable the service
> systemctl enable keepalived.service

Reinstall the keepalived, it is active now
> sudo apt-get install keepalived

> systemctl list-unit-files | grep keepalived
snap-keepalived-448.mount                  disabled      
keepalived.service                         enabled       
snap.keepalived.daemon.service             disabled


References:
https://www.cnblogs.com/lxjshuju/p/7183689.html
http://www.jinbuguo.com/systemd/systemctl.html
https://chubuntu.com/questions/11949/why-are-some-systemd-services-in-the-masked-state.html
http://www.kbase101.com/question/15548.html