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Last updated: Tue, 19 Sep 2006


(PHP 5 >= 5.1.0RC1)

readline_callback_handler_install -- Initializes the readline callback interface and terminal, prints the prompt and returns immediately


bool readline_callback_handler_install ( string prompt, callback callback )

Sets up a readline callback interface then prints prompt and immediately returns. The callback function takes one parameter; the user input returned. Calling this function twice without removing the previous callback interface will automatically and conveniently overwrite the old interface.

The callback feature is useful when combined with stream_select() as it allows interleaving of IO and user input, unlike readline().

Return Values

Returns TRUE on success or FALSE on failure.


Example 1. Readline Callback Interface Example

function rl_callback($ret)
    global $c, $prompting;

    echo "You entered: $ret\n";

    if ($c > 10) {
        $prompting = false;
    } else {
        readline_callback_handler_install("[$c] Enter something: ", 'rl_callback');

$c = 1;
$prompting = true;

readline_callback_handler_install("[$c] Enter something: ", 'rl_callback');

while ($prompting) {
    $n = stream_select($r = array(STDIN), $w = null, $e = null, null);
    if ($n && in_array(STDIN, $r)) {
        // read a character, will call the callback when a newline is entered

echo "Prompting disabled. All done.\n";

Last updated: Tue, 19 Sep 2006