刚刚安装LINUX系统时没有安装工具包，这时候你进入终端，运行IFCONFIG命令就会出错，提示命令无法使用的情况。 

[root@dev ~]# ifconfig
-bash: ifconfig: 未找到命令

1.先看一下环境变量里有没有IFCONFIG命令的路径，因为IFCONFIG是在/SBIN路径下的，ROOT用户登录进去才可以运行，先看一下ROOT用户的环境变量。

[root@dev sbin]# echo $PATH
/opt/easToKafka/jdk1.8.0_161/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/opt/kafka-eagle-web-2.1.0/bin:/root/bin:/opt/mysql/bin
[root@dev sbin]# 

2.再看一下sbin目录下有没有ifconfig

[root@dev sbin]# ll /usr/sbin/ | grep ifconfig 
[root@dev sbin]# 

3.没有ifconfig命令，用yum进行下载，安装ifconfig工具

[root@dev sbin]# yum search ifconfig
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.bupt.edu.cn
 * extras: mirrors.aliyun.com
 * updates: mirrors.aliyun.com
======================================================== 匹配：ifconfig =========================================================
net-tools.x86_64 : Basic networking tools
[root@dev sbin]# 

4.net-tools.x86_64是包含ifconfig命令的工具包的名称，下载这个工具包就行

[root@dev sbin]# yum install net-tools.x86_64

 5.验证ifconfig命令

[root@dev sbin]# ifconfig 
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.78.8  netmask 255.255.255.0  broadcast 192.168.78.255
        inet6 fe80::911e:f5f9:313a:7aa8  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:06:f3:78  txqueuelen 1000  (Ethernet)
        RX packets 2161  bytes 202412 (197.6 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1399  bytes 219336 (214.1 KiB)
        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 1000  (Local Loopback)
        RX packets 32  bytes 2592 (2.5 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 32  bytes 2592 (2.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[root@dev sbin]#