如果你已经安装了npm和node: npm install -g ip && node -e "const ip = require('ip');console.log (ip.address())”

主网口IP

ifconfig `ip route | grep default | head -1 | sed 's/\(.*dev \)\([a-z0-9]*\)\(.*\)/\2/g'` | grep -oE "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b" | head -1

在Mac电脑上，考虑以下问题:

scutil --nwi | grep -Eo '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'

我必须补充科林安德森的回答，这个方法也考虑到如果你有两个界面，他们都显示为向上。

ip route get 1 | awk '{print $NF;exit}'

我一直在用树莓派(Raspberry Pi)开发一个应用程序，需要实际使用的IP地址，而不仅仅是它是否启动。大多数其他答案都会返回两个IP地址，这对我的场景来说不一定有帮助。

ip addr show | grep -E '^\s*inet' | grep -m1 global | awk '{ print $2 }' | sed 's|/.*||'

我只是利用网络接口名称，我的自定义命令是

[[ $(ip addr | grep enp0s25) != '' ]] && ip addr show dev enp0s25 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p' || ip addr show dev eth0 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p' 

在我自己的笔记本上

[flying@lempstacker ~]$ cat /etc/redhat-release 
CentOS Linux release 7.2.1511 (Core) 
[flying@lempstacker ~]$ [[ $(ip addr | grep enp0s25) != '' ]] && ip addr show dev enp0s25 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p' || ip addr show dev eth0 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p'
192.168.2.221
[flying@lempstacker ~]$

但如果网络接口拥有至少一个ip，那么它将显示属于它的所有ip

例如

Ubuntu 16.10

root@yakkety:~# sed -r -n 's@"@@g;s@^VERSION=(.*)@\1@p' /etc/os-release
16.04.1 LTS (Xenial Xerus)
root@yakkety:~# [[ $(ip addr | grep enp0s25) != '' ]] && ip addr show dev enp0s25 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p' || ip addr show dev eth0 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p'
178.62.236.250
root@yakkety:~#

Debian杰西

root@jessie:~# sed -r -n 's@"@@g;s@^PRETTY_NAME=(.*)@\1@p' /etc/os-release
Debian GNU/Linux 8 (jessie)
root@jessie:~# [[ $(ip addr | grep enp0s25) != '' ]] && ip addr show dev enp0s25 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p' || ip addr show dev eth0 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p'
192.81.222.54
root@jessie:~# 

CentOS 6 . 8

[root@centos68 ~]# cat /etc/redhat-release 
CentOS release 6.8 (Final)
[root@centos68 ~]# [[ $(ip addr | grep enp0s25) != '' ]] && ip addr show dev enp0s25 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p' || ip addr show dev eth0 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p'
162.243.17.224
10.13.0.5
[root@centos68 ~]# ip route get 1 | awk '{print $NF;exit}'
162.243.17.224
[root@centos68 ~]#

Fedora 24

[root@fedora24 ~]# cat /etc/redhat-release 
Fedora release 24 (Twenty Four)
[root@fedora24 ~]# [[ $(ip addr | grep enp0s25) != '' ]] && ip addr show dev enp0s25 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p' || ip addr show dev eth0 | sed -n -r 's@.*inet (.*)/.*brd.*@\1@p'
104.131.54.185
10.17.0.5
[root@fedora24 ~]# ip route get 1 | awk '{print $NF;exit}'
104.131.54.185
[root@fedora24 ~]#

link提供的命令ip route get 1 | awk '{print $NF;exit}'似乎更准确，而且更短。