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In a file version control system, identifying a unique identity of a file is the key to implementing change tracking, conflict detection and version management. Although there is no built-in getmyinode function in PHP, we can get the inode number of the file through the fileinode() function. inode is a data structure number used in the file system to uniquely identify files. It has uniqueness and stability, so it plays an important role in version control.
This article will introduce how to use inode to implement the practical application of file version control, focus on explaining its usage methods, and explain it in combination with specific cases.
In a Unix-like file system, each file has an inode number. Inode contains the file's metadata information, such as file permissions, owners, timestamps, etc., but does not include the file name. The inode number is the unique identifier of the file. Even if the file name changes, as long as the inode remains unchanged, the file is essentially the same.
In version control scenarios, the inode number can be used:
Quickly determine whether two files are the same entity.
Auxiliary detection file rename or move.
Avoid repeated uploads or storing the same file.
PHP provides the fileinode() function, which can return the inode number of the file, and the usage method is very simple:
<?php
$file = '/path/to/file.txt';
$inode = fileinode($file);
echo "Filed inode The number is：" . $inode;
?>
In version control, if the user renames the file and the file content is not changed, we usually hope that the version system can recognize this operation to avoid misjudging it as a new file.
Sample code:
<?php
function isSameFileByInode($file1, $file2) {
return fileinode($file1) === fileinode($file2);
}
// Assume the file path before and after renaming
$oldPath = '/var/www/html/file_old.txt';
$newPath = '/var/www/html/file_new.txt';
if (file_exists($oldPath) && file_exists($newPath)) {
if (isSameFileByInode($oldPath, $newPath)) {
echo "File renamed，The content has not changed。";
} else {
echo "Different file content or different files。";
}
} else {
echo "The file path does not exist。";
}
?>
By comparing inode, it can accurately determine whether the file is the same entity.
In distributed or cloud version control systems, avoiding repeated storing of the same files can save space. We can first obtain the inode of the file, combine file size, hash value and other methods to determine the file uniqueness, and reduce redundancy.
Example:
<?php
function getFileSignature($file) {
return [
'inode' => fileinode($file),
'size' => filesize($file),
'hash' => md5_file($file),
];
}
$file1 = '/path/to/file1.txt';
$file2 = '/path/to/file2.txt';
$sig1 = getFileSignature($file1);
$sig2 = getFileSignature($file2);
if ($sig1['inode'] === $sig2['inode']) {
echo "Same file（inodeConsistent）";
} elseif ($sig1['size'] === $sig2['size'] && $sig1['hash'] === $sig2['hash']) {
echo "The content is the same but the files are different（Probably a copy）";
} else {
echo "Different files";
}
?>
Combining inode and content hash judgments improves the accuracy of file uniqueness judgment.
In version control, with metadata such as inode and timestamps, it is possible to quickly detect whether the file is modified. When the inode is detected to be unchanged but the modification time changes, it means that the file has been rewritten; if the inode changes, it may be that the file has been deleted and replaced.
Sample monitoring script:
<?php
$file = '/path/to/important_file.txt';
$previousInode = 12345678; // Assume that the previous recordinode
$previousMTime = 1680000000; // Assume that the previous record修改时间
$currentInode = fileinode($file);
$currentMTime = filemtime($file);
if ($currentInode !== $previousInode) {
echo "The file has been replaced or deleted。";
} elseif ($currentMTime !== $previousMTime) {
echo "File content has been modified。";
} else {
echo "File not changed。";
}
?>
Although there is no function directly named getmyinode in PHP, using fileinode() , you can easily get the inode number of the file. Inode is widely used in version control systems, such as file renaming detection, deduplication storage and file change monitoring. By combining inode and other file metadata, efficient and accurate version management logic can be built.
