Little understanding of Unix System Structure

Linux

UnixLittle understanding of architecture

It can be defined as a software operating system in the strict sense，The software controls the computer hardware resources，Provider operating environment for personal understanding of hardware and software wealthy。We call such software kernel (kernel），It is relatively small，Located in the center of the environment

Kernel system call interface is called (system calls) Shared libraries built on top of the system call interface，Applications can either use the shared library，You can also use the system call。

ShellIt is a special application[……]

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Access、Trunk and Hybrid and this VLAN

The internet

Three modes switch port

On the switch，There are three commonly used configuration mode，Respectively Access (Access)，Trunk (trunk or trunk) as well as Hybrid (Hybrid)，These three interfaces operating mode determines the corresponding interface for processing the attitude data packets on the switch。Nowadays，Routing to elaborate on these three models。

label

Since the switch has divided the virtual LAN VLAN function is，Therefore, it is allowed to switch into the Ethernet frame data marked with a tag，VLAN is used to identify different data flows，To be forwarded。This is what we often[……]

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main (int ac, char * of[])和 main（int argc，char *argv[]) Of some of my understanding

C Programming Development

Observance of the whereabouts of the 100th article，，，Although the content is somewhat illegible

Yesterday, see route on the main (int argc，char *argv[]) The article feels written brief said such a function

Of course first contact functions of this function is not the main (int argc，char *argv[]) But the main (int AC, char * of[]）

They use the same。

Each c language program must have a function called main of[……]

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USB interface to Know

Exchange of Experience

Universal Serial Bus

USB's full name is this,，A blink of an eye，USB 1.0 standard came from the 3.0，of course，Little blue box 3.0 also does not fully into our lives，As it is now around us phone、flat、SLR，Almost still in use USB2.0 standard，Occasionally，People around him or will not tell exactly which line corresponds to which device，What can mix，Which can not。

[warning]
The line can not be mixed is not inserted into the device，Because different shapes，Can insert the，a few[……]

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c language command-line arguments argc,argv

C Programming Development

Start

int main(int argc, const char * argv[])

In the C language learning time，We are writing a program，Then view the results in a terminal run，Enter a number, and so on ...... do not know if you have not tried it allows you to write programs that can accept parameters like system commands it? For example,：ls -al like this。

If you wish to do so，Like above, as to declare it!

among them：

argv： Pointer Pointer

argc： Integer

For chestnuts

Assumptions program[……]

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Commonly used strings in c-number function

C Programming Development

atof(To convert a string into a floating-point number)

Related Functions atoi,atoll,strtod,strtol,strtoul
Header Files #include <stdlib.h>
Defined Functions double atof(const char * nptr);

Function Description atof()It scans the string parameter nptr,Skip over white space characters,Until a few metWord or the sign began to do the conversion,The encounter ended when non-numeric or string(‘/0’)[……]

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What is SELinux

Linux

Profile

SELinux is "Security-Enhanced Linux"Abbreviation，Linux is a US National Security Agency, "NSA = The National Security Agency" and SCC (Secure Computing Corporation) developedExtended mandatory access control security module。

Development reasons

Because a lot of trade secrets stored on the company's business platform server，personal information，It is directly related to the personal data of personal privacy[……]

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Rebuild the OS x was deleted Recovery HD

Mac OS

DESCRIPTION

On OS X，There is always a lot of friends because of various reasons，For example, the dual system，For example, change the SSD, etc., etc.，The system will reluctantly comes with Recovery HD comes with this system rescue mode deleted - I do not think that anyone is simply to 650M of disk space and delete it, right =。= Short，While the system can use cmd + r networking at boot time to download，But at the crucial moment，Still very very inconvenient，Not to mention the U disk to do a system disk so the ......，Today, we teach a method of routing，From the system disk OS X[……]

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