1、命令名称：write
执行权限：所有用户
功能描述：向另外一个用户发送信息，以CTRL+D作为结束
语法：write <用户名>
root向luxh用户发送信息 [root@localhost ~]# write luxh write: luxh is logged in more than once; writing to pts/1 hello,luxh,i am root 用户luxh接收到的信息为 [luxh@localhost ~]$ Message from luxh@localhost.localdomain (as root) on pts/0 at 05:17 ... hello,luxh,i am root
root用户向luxh用户发送信息，luxh用户必须已经登陆，否则是发送不了的。
2、命令名称：wall
执行权限：所有用户
功能描述：向所有用户广播信息
语法：wall [message] [文件名]
root向所有登陆用户发送信息 [root@localhost ~]# wall Happy New Year Broadcast message from root@localhost.localdomain (pts/0) (Thu Nov 22 05:27:49 2012): Happy New Year [root@localhost ~]# 已登陆的用户就可以收到 [luxh@localhost ~]$ Broadcast message from root@localhost.localdomain (pts/0) (Thu Nov 22 05:27:49 2012): Happy New Year
3、命令名称：ping
执行权限：root
功能描述：测试网络连通性
语法：ping [选项] IP地址
在Linux下直接ping ID,按CTRL+C终止命令，否则会一直ping
[root@localhost ~]# ping 192.168.1.1 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 64 bytes from 192.168.1.1: icmp_seq=1 ttl=128 time=6.66 ms 64 bytes from 192.168.1.1: icmp_seq=2 ttl=128 time=6.63 ms 64 bytes from 192.168.1.1: icmp_seq=3 ttl=128 time=3.13 ms 64 bytes from 192.168.1.1: icmp_seq=4 ttl=128 time=4.55 ms 64 bytes from 192.168.1.1: icmp_seq=5 ttl=128 time=6.69 ms 64 bytes from 192.168.1.1: icmp_seq=6 ttl=128 time=5.90 ms 64 bytes from 192.168.1.1: icmp_seq=7 ttl=128 time=2.77 ms 64 bytes from 192.168.1.1: icmp_seq=8 ttl=128 time=2.75 ms 64 bytes from 192.168.1.1: icmp_seq=9 ttl=128 time=5.41 ms 64 bytes from 192.168.1.1: icmp_seq=10 ttl=128 time=7.52 ms
使用 -c 指定ping的次数
[luxh@localhost ~]$ ping -c 4 192.168.1.1 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 64 bytes from 192.168.1.1: icmp_seq=1 ttl=128 time=6.49 ms 64 bytes from 192.168.1.1: icmp_seq=2 ttl=128 time=5.42 ms 64 bytes from 192.168.1.1: icmp_seq=3 ttl=128 time=2.46 ms 64 bytes from 192.168.1.1: icmp_seq=4 ttl=128 time=3.69 ms --- 192.168.1.1 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3010ms rtt min/avg/max/mdev = 2.464/4.520/6.498/1.551 ms [luxh@localhost ~]$
使用 -s 指定发送包的大小，最大不能超过65507字节
[root@localhost ~]# ping -c 4 -s 1024 192.168.1.1 PING 192.168.1.1 (192.168.1.1) 1024(1052) bytes of data. 1032 bytes from 192.168.1.1: icmp_seq=1 ttl=128 time=6.67 ms 1032 bytes from 192.168.1.1: icmp_seq=2 ttl=128 time=4.21 ms 1032 bytes from 192.168.1.1: icmp_seq=3 ttl=128 time=9.06 ms 1032 bytes from 192.168.1.1: icmp_seq=4 ttl=128 time=5.09 ms --- 192.168.1.1 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3010ms rtt min/avg/max/mdev = 4.212/6.262/9.064/1.845 ms [root@localhost ~]#
4、命令名称：ifconfig
执行权限：root
功能描述：查看网络设置信息
语法：ifconfig [-a] [网卡设备标识]
-a 显示所有网卡的信息 （在Linux系统中可以省略，在Unix系统中不能省略）
[root@localhost ~]# ifconfig eth0 Link encap:Ethernet HWaddr 00:0C:29:4C:63:3E inet addr:192.168.0.102 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fe4c:633e/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:4238 errors:0 dropped:0 overruns:0 frame:0 TX packets:3578 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:4560042 (4.3 MiB) TX bytes:299603 (292.5 KiB) Interrupt:19 Base address:0x2024 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:8 errors:0 dropped:0 overruns:0 frame:0 TX packets:8 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:480 (480.0 b) TX bytes:480 (480.0 b)
eth0是实际的物理网卡，lo是虚拟的回环地址网卡
临时改变IP地址，重启后无效 [root@localhost ~]# ifconfig eth0 192.168.1.5
