In PHP, file operations are performed using various functions provided by the programming language. Some commonly used file operations in PHP include:

1. Opening a File:
To open a file in PHP, you can use the `fopen()` function. This function takes two parameters: the file path and the mode in which you want to open the file. For example:

“`php
$file = fopen(“filename.txt”, “r”);
“`

This opens the file named “filename.txt” in read mode.

2. Reading from a File:
To read the contents of a file, you can use the `fread()` function. This function takes two parameters: the file resource returned by the `fopen()` function and the number of bytes to read. For example:

“`php
$contents = fread($file, filesize(“filename.txt”));
“`

This reads the entire contents of the file into the variable `$contents`.

3. Writing to a File:
To write data to a file, you can use the `fwrite()` function. This function takes two parameters: the file resource returned by the `fopen()` function and the data to write. For example:

“`php
fwrite($file, “This is some data”);
“`

This writes the string “This is some data” to the file.

4. Closing a File:
After you have finished working with a file, it is important to close it using the `fclose()` function. This releases any system resources associated with the file. For example:

“`php
fclose($file);
“`

This closes the file resource.

5. Checking if a File Exists:
To check if a file exists before performing any operations on it, you can use the `file_exists()` function. This function takes the file path as a parameter and returns `true` if the file exists, and `false` otherwise. For example:

“`php
if (file_exists(“filename.txt”)) {
// File exists
} else {
// File does not exist
}
“`

These are some of the basic file operations you can perform in PHP. There are other functions available for more advanced file operations, such as renaming a file, deleting a file, etc.