找到类似的命名文件

In PHP, how to search for a file with a similar name? There are three files: file.csv, file.csv.1 and olderfile.csv.

How to find the files file.csv and file.csv.1?

Depend on how you define "similar." And try use regular expression.

$filename = basename("/some/long/path/file.csv");
// Or other vars pointing to your actual file.

$pattern = '/(^file\.csv(?:\.\d|))/';

if(preg_match($pattern, $filename, $matches)){
    print_r($matches);
} else {
    echo "Not found.";
}

You can use the glob() function for this. This should work with the files you mentioned:

foreach (glob("file.csv*") as $filename) {
    echo "$filename
";
}