Linux System call: unlink

The unlink system call in Linux is used to delete (remove) a file from the file system. Once a file is unlinked, it is removed from the directory structure, and its data blocks are marked as available for reuse. However, if a process has the file open, the file’s data remains accessible until the last file descriptor is closed. Here’s how the unlink system call is used:

Syntax:

int unlink(const char *pathname);

Parameters:

• pathname: The path to the file you want to unlink (delete).

Return Value:

• On success, the unlink function returns 0.
• On failure, it returns -1, and you can use the errno variable to determine the specific error.

Example usage:

Suppose you have a file named “example.txt” that you want to delete:

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
int main() {
 const char *filename = "example.txt";
// Unlink (delete) the file
 if (unlink(filename) == -1) {
 perror("Error unlinking file");
 return 1;
 }
printf("File '%s' unlinked successfully.\n", filename);
return 0;
}

In this example, the program uses the unlink function to delete the file named “example.txt”. After calling unlink, the file will be removed from the file system, and any subsequent attempts to access it will result in an error. Keep in mind that once a file is unlinked, it cannot be recovered using normal means, so use this operation carefully.