How to Find the Last 20 Modified Files in Linux (Complete Guide)

Finding the last 20 modified files in Linux can be a useful task, especially when you are trying to keep track of the most recent changes made to files on your system. In this blog post, we will explore different methods to accomplish this in the C programming language.

Introduction

In Linux, the modification time of a file can be tracked using the `stat` system call, which provides information about a file, such as its size, permissions, and timestamps. By utilizing the `stat` system call in a C program, we can retrieve the modification time of files and then sort them based on their timestamps to find the most recently modified ones.

Steps to Find the Last 20 Modified Files

1. Include Necessary Headers: To utilize the `stat` system call, we need to include the appropriate headers in our C program.

“`c
include
include
include
include
include
include
include
“`

2. Implement the Comparison Function: We will define a comparison function to sort the files based on their modification time.

“`c
int compare(const void a, const void b) {
return ((struct stat)b)->st_mtime – ((struct stat)a)->st_mtime;
}
“`

3. Retrieve File Information: We will iterate through the files in a directory using `readdir` and retrieve the `stat` information for each file.

4. Sort the Files: After gathering the file information, we will sort the files based on their modification time using the `qsort` function.

“`c
qsort(files, num_files, sizeof(struct stat), compare);
“`

5. Display Last 20 Files: Finally, we will display the last 20 files based on their modification time.

Putting It All Together

Below is a sample C program that combines the above steps to find the last 20 modified files in a directory:

“`c
include
include
include
include
include
include
include

int compare(const void a, const void b) {
return ((struct stat)b)->st_mtime – ((struct stat)a)->st_mtime;
}

int main(int argc, char argv[]) {
DIR dir;
struct dirent entry;
struct stat info;
struct stat files[100]; // Assuming a maximum of 100 files
int num_files = 0;
dir = opendir(argv[1]);

while ((entry = readdir(dir)) != NULL) {
char path[256];
sprintf(path, “%s/%s”, argv[1], entry->d_name);
stat(path, &info);
files[num_files++] = info;
}

closedir(dir);

qsort(files, num_files, sizeof(struct stat), compare);

printf(“Last 20 Modified Files:\n”);
for (int i = 0; i < 20 && i < num_files; i++) {
printf("%s\n", argv[1]);
}

return 0;
}
“`

Conclusion

In this blog post, we have explored how to find the last 20 modified files in a directory using a C program in Linux. By utilizing the `stat` system call and sorting the files based on their modification time, we can easily identify the most recent modifications made to files on a Linux system. Feel free to modify and improve the provided C program to suit your specific requirements for tracking modified files.