Redhat Linux: Find Out My IP Address

How do I to find out ip address on a CentOS or Fedora or Redhat Enterprise Linux server or desktop system using bash shell or command line options?

You can use any one of the following command to view ip address information for each interface under RHEL / CentOS / Fedora Linux:
[a] ip command: Display or manipulate IP address, routing, devices, policy routing and tunnels.

[b] ifconfig command: It is used to configure the kernel-resident network interfaces as well as display information about it.

ip command example

To see current ip address information for eth0, enter:
# ip addr show eth0
Sample outputs:

2: eth0:  mtu 1500 qdisc mq state UP qlen 1000
    link/ether b8:ac:6f:65:31:e5 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.100/24 brd 192.168.1.255 scope global eth0
    inet6 fe80::baac:6fff:fe65:31e5/64 scope link
       valid_lft forever preferred_lft forever

To see routing information, enter:
# ip route show
Sample outputs:

10.0.xx.yy dev ppp0  proto kernel  scope link  src 10.1.3.199
38.xx.yy.zz via 192.168.1.2 dev eth0  src 192.168.1.100
192.168.1.0/24 dev eth0  proto kernel  scope link  src 192.168.1.100  metric 1
10.0.0.0/8 dev ppp0  scope link
default via 192.168.1.2 dev eth0  proto static

ifconfig command example

Simply type the ifconfig command as follows to display eth0 IP information:
# ifconfig eth0
Sample outputs:

eth0      Link encap:Ethernet  HWaddr b8:ac:6f:65:31:e5
          inet addr:192.168.1.100  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::baac:6fff:fe65:31e5/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:308560 errors:0 dropped:0 overruns:0 frame:0
          TX packets:217836 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:431112624 (431.1 MB)  TX bytes:20994801 (20.9 MB)
          Interrupt:17 

You can simply type the following command to just display an IP and its netmask:
# ifconfig eth0 | grep 'inet addr:'
Sample outputs:

 inet addr:192.168.1.100  Bcast:192.168.1.255  Mask:255.255.255.0