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This article mainly introduces "how to use Linux system library files to reduce workload". In daily operation, I believe many people have doubts about how to use Linux system library files to reduce workload. Xiaobian consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts of "how to use Linux system library files to reduce workload". Next, please follow the editor to study!

In different development environments, there are often library files for children. Library files are codes or programs that implement a particular function. It can be used directly when developing an application. In this way, the development workload can be reduced. Rich library files are also provided in the Linux operating system. To this end, if Linux operating system developers can learn to use this library file, then the workload can be greatly reduced.

Specifically, the Linux system administrator needs to know three aspects. The first is the commonly used library files, the second is the methods called by the library files, and the third is why it is recommended to use shared libraries. Knowing this, the system administrator can call the library files during the program development process. For what the library file contains in the end, the system administrator can refer to the relevant books, the author will not elaborate too much here. The author now only talks about the methods of calling library files and the differences between them, in order to help readers determine whether to use static libraries or dynamic libraries.

First, the calling method of library files.

Use the library file to hide the specific implementation. For example, when using this library file, the system administrator only needs to include the header file where the required function is located. Without having to worry about the specific implementation of this function. It's like making a phone call on a cell phone. The system administrator only needs to know how to make a call from a mobile phone, without knowing how the internal lines are arranged, how the signal is transmitted directly between the two mobile phones, how the digital signal is converted into a voice signal, and so on. I don't need to know any of this. In addition, using library files can reduce the workload of development. Some features may be needed in multiple applications, so there is no need to rewrite code and compile through the library file. To do this, the workload of development can be greatly reduced.

So how can the system administrator call this library file? In the development environment of Linux operating system, there are two main ways of calling. One is a calling method called a static library. That is, at the time of compilation, the binary image code of the corresponding function in the library is copied directly into the currently compiled program. Simply put, it is directly through the copy and paste of the code to reduce the development of the code. This is the same way that some people cobble together when writing a composition. In the Linux operating system, if the library file is suffixed with .a, it is represented as a static library file. When using this static library file, the system administrator can directly open the library file in the editor, copy the code into his own application, and compile it.

The second method of calling is called shared library invocation. If you call the library file in this way, you only need to reference the entry location of the binary impression code of the corresponding function in the library at compile time. The application then reads the function code from the shared library file at run time for indirect reference. In other words, the shared library is like a living room. As long as the user opens a door between the room and the living room, the living room can be used in this room. Static libraries are different. If the static library wants to use this living room, instead of opening a door between the room and the living room, he will include the living room in his own room and integrate it with the room. Therefore, the two invocation methods are very different in implementation mechanism. At the same time, it also determines that they each have their own advantages and disadvantages. When using these library files, the system administrator has to anticipate their advantages and disadvantages, and then choose the appropriate calling method.

Second, the advantages of using shared libraries.

Using the calling method of static library, the advantage is obvious. Because the code of the static file has been integrated with the code developed by the user, there is no need to find the path to the library when executing the application. In this way, you don't need any library support when executing the executable. But its disadvantages are also obvious. If multiple subroutines of this application need to use this library file, then you need to copy multiple pieces of the same code. At this point, it will undoubtedly increase the length of the code and increase the difficulty of maintenance. Most importantly, it can also have a negative impact on the performance of the application. For this reason, unless you develop an application that is simple and performs only a single function, you can use static libraries. In addition, the author suggests that readers should use the shared library. Specifically, the adoption of shared libraries can bring the following advantages.

One is to facilitate the upgrade and maintenance of shared library files. There may also be problems with the files in the shared library, which need to be solved by upgrading the library files. If you use a static library at this point, you will have to change the code that references the library file one by one. When there are ten references in an application, there are ten places you need to change. Obviously, this follow-up maintenance will be a lot of work. But if you use shared library files, it is different. At this point, you only need to change the library files in the shared library. Because only the location of the library file is indicated in the application code. For this reason, as long as the location of the library has not changed, then the code in this application does not need to be changed. Therefore, when the files in the shared library need to be upgraded for reasons such as errors, it will not have the slightest impact on the application. At this point, you only need to overwrite the library file directly without recompiling the application's code. It's like the difference between a SIM card and a PHS without SIM. If the user wants to change the number now, then for PHS with SIM card, you only need to replace one SIM card. For PHS without SIM card, the whole PHS needs to be replaced. This PHS with SIM card is like a shared library, while PHS without SIM is like a static library.

The second is to improve the sharing of code. When multiple subroutines in an application need to use the same library file, the Linux operating system calls the shared library file into the memory unit. At this point, no matter how many subroutines need to use the same code, you only need to put the code in shared memory, instead of loading it directly into the executable file in all places like a static library. It's a lot like watching a movie. Using a shared library is like watching a movie in a cinema. The movie is only shown once, but many people can watch it together. Using a static library is like watching a movie in your own home theater. If three families want to watch the same movie, they have to open the home theater to watch it in their own homes. There is no doubt that the utilization rate of home theaters is not high, at least not as high as the equipment in cinemas. At the same time, this will also increase the load of the system. Each family uses its own home theater, which would cost twice as much power if there are three families. Therefore, the use of shared libraries can greatly save system resources, especially memory overhead, which can make applications run faster. The more complex the application you develop, or the more likely you are to use the same code, the more obvious the performance improvement will be.

However, there is a big drawback in using this shared library file, that is, the executable file has a certain dependency with the library file. If an executable file is in the form of a shared library, it calls a library file. However, when the executable runs on other Linux operating systems, it is very likely that the library file does not exist or the version is relatively low, and the executable may not run or run in error. To avoid this, sometimes you have to distribute the library files you need along with the executable files. In addition, in coding, you must specify the search location of the library file. Otherwise, the location of the library file will not be found when the application is executed.

But then again, the defects of this shared library reference can be solved. Therefore, compared with its advantages, these defects are not worth mentioning. As long as the necessary verification is carried out before the software is packaged or installed, the negative impact of this defect on the application can be well avoided. Generally speaking, the author suggests that we should use the shared library to invoke the library files. Especially when designing large applications or applications that may have performance bottlenecks, the use of shared libraries will help system administrators improve the performance of their applications.

At this point, the study on "how to use Linux system library files to reduce workload" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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