readline_callback_handler_install()

readline_callback_handler_install() — Initializes the readline callback interface and terminal, prints the prompt and returns immediately.

Built-in function of PHP 8.5. The manual lists it as available in PHP 5 >= 5.1.0, PHP 7, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

What it does

Sets up a readline callback interface then prints prompt and immediately returns. Calling this function twice without removing the previous callback interface will automatically and conveniently overwrite the old interface.

Signature

readline_callback_handler_install(string $prompt, callable $callback): true

Parameters

Return value

Always returns true.

Example

A runnable snippet:

function rl_callback($ret) { global $c, $prompting; echo "You entered: $ret\n"; $c++; if ($c > 10) { $prompting = false; readline_callback_handler_remove(); } else { readline_callback_handler_install("[$c] Enter something: ", 'rl_callback'); } } $c = 1; $prompting = true; readline_callback_handler_install("[$c] Enter something: ", 'rl_callback'); while ($prompting) { $w = NULL; $e = NULL; $n = stream_select($r = array(STDIN), $w, $e, null); if ($n && in_array(STDIN, $r)) { // read a character, will call the callback when a newline is entered readline_callback_read_char(); } } echo "Prompting disabled. All done.\n";

Changelog

See also

readline_callback_handler_remove(), readline_callback_read_char(), stream_select()

All PHP 8.5 built-in functions

Reference card built from the PHP manual page readline_callback_handler_install() (PHP documentation, CC BY 3.0). The page is generated from the manual, so the wording of the parameter and return value text follows php.net.