Using ip command

ip add

example output

bob@localhost:~$ ip add
 1: lo:  mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
     inet 127.0.0.1/8 scope host lo
        valid_lft forever preferred_lft forever
     inet6 ::1/128 scope host
        valid_lft forever preferred_lft forever
 2: eno1:  mtu 1500 qdisc mq state UP group default qlen 1000
     link/ether 38:ea:a7:13:a4:fe brd ff:ff:ff:ff:ff:ff
     inet 192.168.1.21/24 brd 192.168.1.1 scope global dynamic noprefixroute eno1
        valid_lft 513sec preferred_lft 513sec
     inet6 13ac::98fe::ae78:d1ff/64 scope link noprefixroute
        valid_lft forever preferred_lft forever
 bob@localhost:~$ 

ifconfig

You may need to install net-tools to use

ifconfig  

example output

bob@localhost:~$ ifconfig 
eno1: flags=4163  mtu 1500
         inet 192.168.200.58  netmask 255.255.255.0  broadcast 192.168.1.21
         inet6  13ac::98fe::ae78:d1ff  prefixlen 64  scopeid 0x20
         ether b8:ac:6f:91:01:e8  txqueuelen 1000  (Ethernet)
         RX packets 184950632  bytes 9487577263452
         RX errors 0  dropped 0  overruns 0  frame 0
         TX packets 128473456  bytes 234612443785 
         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Using the hostname command

hostname -I

Output is just the IP address. Example below

192.168.1.21