Linux study NOTE _ 3_common Linux commands _ 6 _ network communication commands

Network Communication commands (relatively simple): 1. writeusrbinwritewrite [user name] is used to send information to the user, provided that the user has logged on to the server host, otherwise, therefore, write is a real-time communication tool

Network Communication commands (relatively simple ):

1. write/usr/bin/write

Write [user name]

Used to send information to a user, provided that the user has logged on to the server host

Otherwise, there is no way to leave a message for him. therefore, write is a real-time communication tool.

End the communication with Ctrl + D

E.g. write guest

2. wall [write all]/usr/bin/wall

Used to broadcast information to all users

Wall [message] [file name]

3. ping/usr/sbin/ping can only be executed by the root user.

Test network connectivity

Ping [option] IP address

Unlike Windows, you must press ctrl + c to stop running.

-C [count]: pingc stops running.

Ping-c 4 192.168.9.5: serves the same purpose as Windows.

-S [size]: change the package size, but there is a certain size limit

Ping-s 6000 192.168.1.1

Appendix: how to troubleshoot network faults in Linux

1) ping the host of the other party. if the host can be pinged, the network is normal.

2) you cannot ping the local IP address.

If the ping is successful, the TCP/IP protocol is correct.

3) the local IP address cannot be pinged. ping 127.0.0.1 and ping back the IP address.

If the ping is successful, it indicates that the TCP/IP protocol is not installed properly. if the TCP/IP protocol is installed, the IP address can be pinged even if there is no Nic.

In addition, even if a host is pinged but cannot be pinged, the network may not be faulty. in many cases, this situation may occur and you will learn it carefully later.

4. ifconfig/usr/bin/ifconfig

Used to view Nic information

The-a option is added by default in Linux, but in UNIX systems, the "-a" option must be added.

E.g. ifconfig

Ifconfig eth0 // view only the physical Nic

Ifconfig ech0 192.168.1.104 // Set the IP address ~, Only temporarily effective

Linux rules: to change the settings, you must write the configuration file