ftp_put()

The PHP ftp_put() function

ftp_put() is a built-in PHP function that uploads a local file to a remote FTP server. It is the upload counterpart of ftp_get(), which downloads a remote file to your machine. This page covers the signature, the all-important transfer modes, a complete working flow, error handling, and the gotchas that trip people up in production.

You reach ftp_put() after you have opened a connection with ftp_connect() and authenticated with ftp_login().

Syntax

ftp_put(
    FTP\Connection $ftp,
    string $remote_filename,
    string $local_filename,
    int $mode = FTP_BINARY
): bool

Returns true on success and false on failure.

Version note: Before PHP 8.1 the first argument was a resource returned by ftp_connect(). From PHP 8.1 it is an FTP\Connection object. Your code does not change — you still pass whatever ftp_connect() returns — but is_resource() checks no longer work on it.

Binary vs. ASCII mode

Choosing the wrong mode is the most common cause of "the upload worked but the file is corrupt":

• FTP_BINARY transfers the bytes exactly as-is. Use it for everything by default — images, archives, PDFs, executables, and even text in practice.
• FTP_ASCII rewrites line endings (\n ↔ \r\n) to match the destination platform. Only meaningful for plain text, and it will silently destroy any binary file. When in doubt, stay on FTP_BINARY.

A complete upload

Always check the return values of each FTP call rather than assuming a step succeeded:

<?php

// 1. Open a connection (false on failure)
$ftp = ftp_connect('ftp.example.com');
if ($ftp === false) {
    exit("Could not connect to FTP server.\n");
}

// 2. Authenticate
if (!ftp_login($ftp, 'username', 'password')) {
    ftp_close($ftp);
    exit("FTP login failed.\n");
}

// 3. Behind a firewall/NAT? Passive mode is almost always required.
ftp_pasv($ftp, true);

// 4. Upload: local file -> remote path, binary mode
$ok = ftp_put($ftp, '/public_html/index.html', './build/index.html', FTP_BINARY);

echo $ok
    ? "Upload succeeded.\n"
    : "Upload failed.\n";

// 5. Always close
ftp_close($ftp);

Note the argument order: remote destination first, local source second — the reverse of what many people expect. Mixing these up makes PHP try to read a non-existent local file and the call fails.

Error handling

ftp_put() returns false and emits a PHP warning on failure. Convert that into a clear, actionable result instead of letting a stray warning leak into your output:

<?php

$remote = '/public_html/index.html';
$local  = './build/index.html';

// Catch the "no such local file" case before touching the network.
if (!is_readable($local)) {
    exit("Local file '$local' is missing or unreadable.\n");
}

if (!ftp_put($ftp, $remote, $local, FTP_BINARY)) {
    // Common causes: wrong remote directory, no write permission,
    // disk quota exceeded, or passive mode not enabled.
    echo "Failed to upload '$local' to '$remote'.\n";
} else {
    echo "Uploaded '$local' to '$remote'.\n";
}

ftp_close($ftp);

Common failure causes

• Wrong argument order — remote path and local path swapped.
• Passive mode not set — most servers behind NAT need ftp_pasv($ftp, true) after login.
• Missing remote directory — ftp_put() does not create folders; use ftp_mkdir() first.
• No write permission or quota exceeded on the server side.
• Wrong transfer mode corrupting a binary file (use FTP_BINARY).

Uploading from an open stream

If your data is already an open file handle (or comes from a stream wrapper rather than a path on disk), use ftp_fput() instead — it takes a stream resource in place of a local filename.

Conclusion

ftp_put() uploads a local file to a remote FTP server. Remember the three things that cause most problems: pass the remote path first, keep FTP_BINARY unless you have a specific reason for ASCII, and check every return value. For non-blocking transfers that don't stall your script, see ftp_nb_put().

Practice