. Neter Linux series four: Linux shell introduction and TCP, IP base

One, the shell under Linux

Overview: After a successful login to Linux, the system will appear a different prompt symbol, such as $, ~, #等, and then you can start to enter the required command, if the command is correct, the system will be executed according to the requirements of the command, until the system is logged off, during logon to logoff, Each command you enter will be interpreted and executed frequently. and the responsible mechanism is the shell. In fact, the command-language interactive interpretation and execution of user input commands is only one aspect of shell functionality, the shell can also be used for programming, it provides the means to define variables and parameters and rich program control structure. Using shell programming is similar to a batch file in DOS, called shell script, or shell or shell command files.

As shown in the following:

Second, the shell classification

Overview: There are many shells, but there are several common ones:

Shell name Developer Command name

Bourne s.r.bourne/bin/sh->/bin/bash (mainland)

Bill joy/bin/csh C.

Kom David/bin/ksh

Look at the shell types on Ubuntu:

See what kind of shell is currently in use

Command: ENV "show environment variables for current system"

If you do not want to use Bash's shell commands, you can make changes to the command:

Chsh-s Enter a new shell such as:/bin/dash

Chsh-s/bin/dash, and then log off.

I'm not going to try it here.

Three, small tricks

(1) The completion of the shell command: refers to the user Input command, do not need to enter the full command, and the system will automatically find the most consistent name. This feature saves time when you frequently enter commands. Direct input "MK"--and then press the "tab" key--there are two letters "MK" at both ends of the command. Cat P then press the TAB key twice to see all the files or directories that begin with "P".

(2) Under Linux, we may sometimes want to know or use recently executed commands, and history may be a big help.

1. History 5: This description shows the 5 most recently used commands.

2,! 5: This indicates the execution of a command with a history number of 5.

3.!ls: This note executes the last command that starts with "LS".

If you do not want to enter a command, you can use this:

Iv. Basics of TCP/IP

Here is a brief introduction, about more in-depth things, you can refer to other information, "TCP/IP Detailed Volume 1: Protocol"

Overview: Linux/unix World is the world of networks, and the basis of the network is TCP/IP, in a sense, the UNIX network is TCP/IP, and TCP/IP is the standard of network interconnection. It is not a separate protocol, but a set of protocols. (Tcp,ip, Udp,arp,rarp and other agreements). So a good programmer must understand and master what is TCP/IP,TCP/IP?

• Routing of IP addresses and packets

Each host and router on the Internet has an IP address, which includes the network number and the host number, all IP addresses are 32-bit (and of course now has IPV6), and IP addresses are divided into a,b,c,d,e five types according to international standards.

OK, today is about here, this series of articles temporarily updated here, there are probably still three articles, I think you can, I hope the recommendation ha ~ Your recommendation is my motivation.

Guo Yan

Source: http://www.cnblogs.com/runningsmallguo/

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. Neter Linux series four: Linux shell introduction and TCP, IP base