get_host_info

The mysqli_get_host_info() function returns a single string that describes how your PHP script is connected to the MySQL server — the host name together with the transport (TCP/IP, a Unix socket, or a named pipe). This page explains the syntax, the values you can expect back, both the procedural and object-oriented styles, and the practical cases where the function is worth reaching for.

What get_host_info() returns

mysqli_get_host_info() is a built-in PHP function that, given an open MySQLi connection, returns a human-readable string describing the connection type and host. Typical return values are:

• localhost via TCP/IP — connected to the local server over a network socket.
• Localhost via UNIX socket — connected through a local Unix domain socket (the default on Linux/macOS when the host is localhost).
• 127.0.0.1 via TCP/IP — connected to an explicit IP over TCP/IP.
• db.example.com via TCP/IP — connected to a remote host.

It is read-only and never changes the connection; it simply reports the transport the driver negotiated. That makes it handy for debugging (confirming you really hit the socket/host you expected) and for logging connection diagnostics.

Syntax

mysqli_get_host_info(mysqli $mysqli): string

Return value: a string describing the server connection type. It never returns false; if the link is invalid PHP raises a warning instead.

Procedural style

Pass the connection object returned by mysqli_connect():

<?php
$mysqli = mysqli_connect("localhost", "username", "password", "database");

if (!$mysqli) {
    die("Connection failed: " . mysqli_connect_error());
}

echo "Host information: " . mysqli_get_host_info($mysqli);

mysqli_close($mysqli);
?>

We first call mysqli_connect() to open the connection, then check the result so we can fail cleanly with mysqli_connect_error() instead of triggering warnings. Passing the link to mysqli_get_host_info() returns the transport description, which we print. On a Linux host using localhost, the output looks like:

Host information: Localhost via UNIX socket

Object-oriented style

The procedural function has an equivalent property on the mysqli object, get_host_info:

<?php
$mysqli = new mysqli("localhost", "username", "password", "database");

if ($mysqli->connect_errno) {
    die("Connection failed: " . $mysqli->connect_error);
}

echo "Host information: " . $mysqli->get_host_info;

$mysqli->close();
?>

Both styles return the same string. Note that in the object-oriented form get_host_info is accessed as a property, not called as a method.

When would I use it?

• Verifying the transport. Forcing TCP/IP (e.g. by using 127.0.0.1 instead of localhost) is sometimes needed for tooling or TLS. get_host_info() confirms which one you actually got.
• Connection logging. Recording the host string alongside connection stats gives you a quick at-a-glance record of where a request connected.
• Troubleshooting "it works locally but not in production." A surprising via UNIX socket vs via TCP/IP often explains permission or firewall differences.

Common gotchas

• Do not confuse it with the $_SERVER superglobal. $_SERVER['SERVER_NAME'] describes the web server handling the HTTP request; mysqli_get_host_info() describes the database connection — two unrelated things.
• The string is for humans, not parsing. If you need structured values, inspect the host you passed to mysqli_connect() rather than splitting this string.
• For the MySQL client library version (rather than the connection host), use mysqli_get_client_info(); for the server side, use mysqli_get_server_info().

Conclusion

mysqli_get_host_info() is a small but practical diagnostic function: it reports how your script reached the MySQL server. Use it when you need to confirm or log the connection transport, and reach for mysqli_get_proto_info() or mysqli_get_connection_stats() when you need more detail.

Practice