[Linux Create Temporary File API] The fleeting light in programming: the art and wisdom of temporary files. Analysis of tmpnam, tmpfile, mkstemp, mkdtemp and other functions…

Directory title

Chapter 1: Understanding the Creation and Management of Temporary Files
- 1. Use the `tmpnam` function
- - Details summary
Chapter 2: Exploring the life cycle management of temporary files
- 1. Use the `tmpfile` function
- 2. Use the `mkstemp` and `mkdtemp` functions
- - Life cycle comparison
Chapter 3: Practical applications and best practices of temporary files
- 1. Security of temporary files
- 2. Naming and storage of temporary files
- 3. Error handling of temporary files
- - Best Practice Summary
Conclusion

Chapter 1: Understanding the Creation and Management of Temporary Files

In computer science, temporary files (or temporary data) are files that are created for a short period of time to facilitate information processing, backup, and editing. They are like sticky notes in people’s daily lives, disposable but indispensable during use. In this chapter we will delve into the different methods of creating temporary files and their characteristics.

1. Use the `tmpnam` function

The tmpnam function provides a convenient solution when we need to generate a temporary file name. Using this function we can get a unique file name that does not already exist in the file system. It’s like making sure our secret diary has a unique lock that only we know how to open.

 char *tmpnam(char *str);
// Generate a string that is a legal path name and does not duplicate any existing file.
// Each function call generates a different string until TMP_MAX times.
//Return value: Generate and return a valid temporary file name that did not exist before. If str is empty, only the temporary file name is returned.

Chinese description: The tmpnam function is used to generate a unique temporary file path name.
English description: The tmpnam function is used to generate a unique temporary file path name.

When generating temporary filenames, people generally don’t want to reuse old filenames, like they want a fresh start on a new day. tmpnam guarantees that each call will generate a new file name until the TMP_MAX number of times is reached.

If the str parameter is set to NULL, then tmpnam will generate a temporary path name in the static area of the memory, which we can think of as a public The name was written on the whiteboard. If called again and passed NULL, the previous name will be overwritten by the new name. If str is not NULL, the pathname will be written into the array pointed to by str. This is more like how we record this pathname. in your own notebook so that it won’t be easily rewritten. Therefore, when str is not NULL, we need to ensure that this notebook (array) has enough space to accommodate the pathname, at least L_tmpnam code> length space, this length is a constant defined in the stdio.h file.

In this process, it is not difficult for us to find that the tmpnam function is like our memory. Every time it is called, a new name will be generated, but if it is not recorded, the old memory will be New coverage. As the Russian writer Tolstoy said in “War and Peace”: “The unmemorized past is like no future.” The names we generate using tmpnam also need to be properly preserved so that future use.

Details summary

The following table summarizes the key points of the tmpnam function:

Parameters	Description	Analogy
The file name generated by `str` for `NULL`	is saved in the static area and will be overwritten by the next call.	Public whiteboard, easily covered by new content.
`str` Non-`NULL`	The generated file name is saved in `str` in the array pointed to.	Personal notebook, the content is relatively stable.
`L_tmpnam`	`str` The minimum required length of the array.	The notebook is large enough to record necessary information.

Chapter 2: Exploring the life cycle management of temporary files

In the world of programming, creating files is just the beginning. Managing their life cycle is the key to keeping your program clean and efficient. As the French philosopher Voltaire mentioned in “The Defender”: “Disorder and chaos are the source of chaos.” This also applies to file management, where the life cycle management of temporary files becomes order and Guarantee of efficiency.

1. Use the `tmpfile` function

The tmpfile function creates a temporary file and opens it in binary update mode. This file is automatically deleted when the program ends or the file stream is closed. It is like an impromptu speech in life. After the end, all that is left is the applause and memories of the audience, rather than a physical recording or video.

 FILE *tmpfile(void);
  //Create a temporary file in binary update mode (wb +). Temporary files created are automatically deleted when the stream is closed or when the program terminates.
   //Return value: If successful, return the file pointer. If an error occurs, return NULL.

Chinese description: tmpfile Creates a temporary file in binary update mode that is automatically deleted when no longer needed.
English description: The tmpfile function creates a temporary file in binary update mode that is automatically deleted when no longer needed.

This self-managed life cycle is a major feature of tmpfile and does not require the programmer to explicitly delete it. This is equivalent to us having an automatic cleaning robot that will clean up the scene by itself after completing the task, so that our attention can be focused on more important things.

2. Use the `mkstemp` and `mkdtemp` functions

Unlike tmpfile, the temporary files and directories created by the mkstemp and mkdtemp functions are not automatically deleted. They are more like temporary rental accommodation. It still existed after we left until we decided to clean it up ourselves.

Chinese description: mkstemp creates a unique temporary file, mkdtemp creates a unique temporary directory, they are not automatically deleted.
English description: The mkstemp function creates a unique temporary file and mkdtemp creates a unique temporary directory; neither is automatically deleted.

 int mkstemp(char *template);
  //Create a regular file with a unique name (regular file) permission bit: S_IRUSR|S_IWUSR
   //Return value: If successful, return the file descriptor. If an error occurs, return -1.
  char *mkdtemp(char *template);
   //The mkdtemp function creates a folder (directory) with a unique name. Permission bits: S_IRUSR|S_IWUSR|S_IXUSR
   //Return value: If successful, return a pointer to the directory name. If an error occurs, return NULL.

Both mkstemp and mkdtemp require a template string that ends with six ‘X’s. The function will replace these ‘X’s with random characters to ensure the file name Or the uniqueness of the directory name. It’s like picking a house number for our temporary home, making sure no one enters by mistake.

Life cycle comparison

Let’s use a table to compare these two temporary file life cycle management methods:

Function	Life cycle management	Automatic deletion	Analogy
`tmpfile`	Deleted when the file stream is closed or the program terminates	Yes	Impromptu The speech disappears as soon as it ends
`mkstemp`/`mkdtemp`	Needs to be deleted manually	No	Temporary rental accommodation needs to be cleaned after use

Through this comparison, we can clearly see that tmpfile provides a convenient way without additional maintenance, while mkstemp and mkdtemp Gives programmers more control, but also increases management responsibilities. When deciding which method to use, like every choice we make in life, there is a trade-off between convenience and responsibility.

Chapter 3: Practical applications and best practices of temporary files

Temporary files are like meteors in real life. Although they are short-lived, they play an irreplaceable role in their momentary existence. They play an important role in protecting data from accidental corruption, offloading memory pressure when processing large amounts of data, or in keeping sensitive information private. As the British poet Byron said in “Child Harold’s Pilgrimage”: “The shortest life may also be the most valuable.” The short existence of temporary documents reflects this point.

1. Security of temporary files

Security is the primary issue that must be considered when working with temporary files. Because temporary files may contain sensitive information, you must ensure that they are properly disposed of after use. From a psychological perspective, this pursuit of security stems from humans’ instinctive need for a stable and predictable environment.

In program design, we can avoid the leakage of sensitive information by ensuring that temporary files are deleted immediately after use. For example, use the tmpfile function to automatically delete a file, or call the delete function immediately after using mkstemp or mkdtemp, just like we do after a private meeting Destroy records immediately to protect information security.

2. Naming and storage of temporary files

For naming, it is important to ensure that the template string is correct when using mkstemp or mkdtemp. The template string must end with six ‘X’ characters, which ensures that the generated filename is unique. It’s like setting a complex password for our secret base. Only those who know the password can find it.

In terms of storage, temporary files should be placed in appropriate directories, such as the system’s temporary folder. In multi-user systems, you should also consider file permission settings to ensure that only the appropriate users or programs can access these temporary files.

3. Error handling of temporary files

There’s always a chance you’ll encounter errors when creating and using temporary files. For example, insufficient disk space, permission issues, or system limitations. Programs should be able to handle these exceptions gracefully rather than letting errors lead to larger problems. This is just like adversity in life. A person’s maturity lies in his attitude and handling of difficulties.

Best Practice Summary

Let’s use a table to summarize best practices when working with temporary files:

Practice	Explanation	Analogy
Safe Delete	Delete temporary files immediately after use to prevent data leakage.	Destroy records after private meetings.
Name it correctly	Use six ‘X’-terminated template strings to ensure uniqueness.	Set complex passwords to protect secret bases.
Proper storage	Store temporary files in the system’s temporary directory.	Store valuables in a safe.
Error handling	Elegantly handle errors when creating and using temporary files.	Remain calm and rational in the face of adversity.

Temporary files, although their life cycle is short, using them correctly and wisely can greatly simplify the complexity of a program while ensuring efficiency and security. In every programming decision lies a deep understanding of human behavior and thinking.

Conclusion

In our programming learning journey, understanding is an important step for us to move to a higher level. However, mastering new skills and ideas always requires time and persistence. From a psychological point of view, learning is often accompanied by constant trial and error and adjustment, which is like our brain gradually optimizing its “algorithm” for solving problems.

That’s why when we encounter mistakes, we should view them as opportunities to learn and improve, not just as annoyances. By understanding and solving these problems, we can not only fix the current code, but also improve our programming skills and prevent making the same mistakes in future projects.

I encourage everyone to actively participate and continuously improve their programming skills. Whether you are a beginner or an experienced developer, I hope my blog will be helpful on your learning journey. If you find this article useful, you may wish to click to bookmark it, or leave your comments to share your insights and experiences. You are also welcome to make suggestions and questions about the content of my blog. Every like, comment, share and attention is the greatest support for me and the motivation for me to continue sharing and creating.

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