• 1
  ifconfig命令是设置或显⽰⽹络接⼝的程序，可以显⽰出我们机器的⽹卡信息，可是有些时候最⼩化安装CentOS等Linux发⾏版的时候会默认不安装ifconfig等命令，这时候你进⼊终端，运⾏ifconfig命令就会出错。

• 2
  ⾸先想到是不是环境变量⾥没有ifconfig命令的路径，因为ifconfig是在/sbin路径下的，以root⽤户登录才可以运⾏，看看root⽤户的环境变量。

• 3
  环境变量⾥有/sbin这个路径，也就是说如果ifconfig命令存在并且就是位于/sbin⽬录下的话肯定就是可以运⾏的，那么就看看/sbin⽬录下有没有ifconfig命令。结果表明/sbin⽬录下并没有ifconfig命令，所以：CentOS⾥边是没有安装ifconfig。

• 4
  解决办法：使⽤yum安装ifconfig
  通过yum search 这个命令我们发现ifconfig这个命令是在net-tools.x86_64这个包⾥，接下来只要安装这个包就⾏了。

yum search ifconfig

[root@host-19-15-62-17 ~]# yum search ifconfig
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
============================================== Matched: ifconfig ===============================================
net-tools.x86_64 : Basic networking tools

yum install net-tools.x86_64

[root@host-19-15-62-17 ~]# yum install net-tools.x86_64
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package net-tools.x86_64 0:2.0-0.25.20131004git.el7 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================================================
 Package                 Arch                 Version                                 Repository           Size
================================================================================================================
Installing:
 net-tools               x86_64               2.0-0.25.20131004git.el7                Media               306 k

Transaction Summary
================================================================================================================
Install  1 Package

Total download size: 306 k
Installed size: 917 k
Is this ok [y/d/N]: y
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : net-tools-2.0-0.25.20131004git.el7.x86_64                                                    1/1 
  Verifying  : net-tools-2.0-0.25.20131004git.el7.x86_64                                                    1/1 

Installed:
  net-tools.x86_64 0:2.0-0.25.20131004git.el7                                                                   

Complete!

• 5
  检查是否安装成功

[root@host-19-15-62-17 ~]# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1400
        inet 19.15.0.17  netmask 255.255.255.0  broadcast 19.15.62.255
        inet6 fe80::f816:3eff:fe9a:99ec  prefixlen 64  scopeid 0x20<link>
        ether fa:16:3e:9a:99:ec  txqueuelen 1000  (Ethernet)
        RX packets 23662897  bytes 1747768097 (1.6 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1606792  bytes 160965520 (153.5 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1400
        inet 192.168.0.60  netmask 255.255.255.0  broadcast 192.168.190.255
        inet6 fe80::f816:3eff:fe62:e04d  prefixlen 64  scopeid 0x20<link>
        ether fa:16:3e:62:e0:4d  txqueuelen 1000  (Ethernet)
        RX packets 25650202  bytes 6366995954 (5.9 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 48709941  bytes 7113139878 (6.6 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 0  (Local Loopback)
        RX packets 39  bytes 3647 (3.5 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 39  bytes 3647 (3.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[root@host-19-15-62-17 ~]# 

• 6
  原来Linux的ifconfig命令来源于net-tools，这个包有ifconfig，netstat，whois等命令，所以不安装这个包的话是无法运行相关命令的。