How to Efficiently Search for Strings in Files with PHP

Finding Strings in Files with PHP

In web development, it's often necessary to check if a specific string is present within a file. This article demonstrates a method to accomplish this task in PHP.

Problem Statement

The following PHP code attempts to verify if a file contains a string sent to the page through a GET request. However, it returns incorrect results:

<code class="php">    // ...
    while (($buffer = fgets($handle)) !== false) {
        if (strpos($buffer, $id) === false)
            $valid = TRUE;
    }
    // ...</code>

Solution 1: file_get_contents()

A more efficient approach is to use the file_get_contents() function, which loads the entire file into memory:

<code class="php">    if( strpos(file_get_contents("./uuids.txt"),$_GET['id']) !== false) {
        // ...
    }</code>

Solution 2: exec()

For large files, it's preferable to use exec() to avoid potential memory issues:

<code class="php">    if( exec('grep '.escapeshellarg($_GET['id']).' ./uuids.txt')) {
        // ...
    }</code>

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