PsySH as a REPL

PsySH functions as a REPL for PHP right out of the box! Once you’ve installed PsySH, running it directly (psysh or ./psysh) will drop you into an interactive prompt, like so:

~ $ ./psysh
Psy Shell v0.1.0-dev (PHP 5.4.9-4ubuntu2.2 — cli) by Justin Hileman

From here, you can type PHP code and see the result interactively:

>>> function timesFive($x) {
...     $result = $x * 5;
...     return $result;
... }
=> null
>>> timesFive(10);
=> 50

PsySH as a Debugger

To use PsySH as a debugger, install it as a Composer dependency or include the Phar directly in your project:


Then, drop this line into your script where you’d like to have a breakpoint:


… which is just a shorter way of saying:


When your script reaches this point, execution will be suspended and you’ll be dropped into a PsySH shell. Your program state is loaded and available for you to inspect and experiment with.

Pro Tip™: You don’t have to use get_defined_vars… You can pass anything you want in as your debugging context:

$result = \Psy\Shell::debug(['app' => $myApp]);

If you’re starting the debug shell from inside a class context, you can pass an optional second argument to add a bound object to the shell. This is super useful because you’ll be able to call things on $this inside your debug shell, and you will have full access to private and protected members of your current context:

\Psy\Shell::debug(get_defined_vars(), $this);

If you call the shortcut eval(\Psy\sh()) from inside a class context, you’ll get $this bound for free.

Magic Variables

The result of the last (successful) statement is available as $_, and the last error or exception is available as $_e. You can use these just like you’d use any other variable:

>>> 'wat'
=> "wat"
>>> $_
=> "wat"
>>> throw new Exception($_)
Exception with message 'wat'
>>> $_e
=> <Exception #000000004db607ea000000017892abf1> {
       message: "wat",
       file: "phar:///psysh/src/Psy/ExecutionLoop/Loop.php(67) : eval()'d code",
       line: 1


While PsySH strives to detect the right settings automatically, you might want to configure it yourself. Just add a file to ~/.config/psysh/config.php (or C:\Users\{USER}\AppData\Roaming\PsySH\config.php on Windows).


PsySH config files are PHP, so you can do pretty much anything you want in there.

Automatically load Composer dependencies

Add something like this to the top of your PsySH config:


// Automatically autoload Composer dependencies
if (is_file(getcwd() . '/vendor/autoload.php')) {
    require_once(getcwd() . '/vendor/autoload.php');

This shouldn’t be necessary if you’ve installed PsySH as a Composer dependency (or dev dependency) for your project. It will already be using the Composer autoloader in that case.

Use local config files

You can easily use project-specific config files, without needing to specify a --config param. Just add this to the top of your PsySH config:


// Use local config, if available
if (is_file(getcwd() . '/.psysh.php')) {
    return require(getcwd() . '/.psysh.php');

// Fall back to global config
return [
    'startupMessage' => '<info>Using global config</info>',

    'commands' => [
        new \Psy\Command\ParseCommand,

… then drop a local .psysh.php config file in your project directory:


return [
    'startupMessage' => sprintf('<info>Using local config: %s</info>', __FILE__),

Note that this example returns the result, so you can fall back to global config if the local one isn’t available. If you want to merge configurations, or even make it cascading (like .gitignore) you can do that, too:


 // Global config
$config = [
    'startupMessage' => '<info>Using global config</info>',

    'commands' => [
        new \Psy\Command\ParseCommand,

// Inherit config from all parent directories, like .gitignore does
$chunks = explode('/', __DIR__);
while (count($chunks) !== 0) {
    $path[] = array_shift($chunks);
    $file = implode('/', $path) . '/.psysh.php';
    if (is_file($file)) {
        $localConfig = require($file);
        $config = array_merge($config, $localConfig);

return $config;

All the options


return array(
    // In PHP 5.4+, PsySH will default to your `cli.pager` ini setting. If this
    // is not set, it falls back to `less`. It is recommended that you set up
    // `cli.pager` in your `php.ini` with your preferred output pager.
    // If you are running PHP 5.3, or if you want to use a different pager only
    // for Psy shell sessions, you can override it here.
    'pager' => 'more',

    // Sets the maximum number of entries the history can contain.
    // If set to zero, the history size is unlimited.
    'historySize' => 0,

    // If set to true, the history will not keep duplicate entries.
    // Newest entries override oldest.
    // This is the equivalent of the HISTCONTROL=erasedups setting in bash.
    'eraseDuplicates' => false,

    // By default, PsySH will use a 'forking' execution loop if pcntl is
    // installed. This is by far the best way to use it, but you can override
    // the default by explicitly enabling or disabling this functionality here.
    'usePcntl' => false,

    // PsySH uses readline if you have it installed, because interactive input
    // is pretty awful without it. But you can explicitly disable it if you hate
    // yourself or something.
    'useReadline' => false,

    // PsySH automatically inserts semicolons at the end of input if a statement
    // is missing one. To disable this, set `requireSemicolons` to true.
    'requireSemicolons' => true,

    // PsySH uses a couple of UTF-8 characters in its own output. These can be
    // disabled, mostly to work around code page issues. Because Windows.
    // Note that this does not disable Unicode output in general, it just makes
    // it so PsySH won't output any itself.
    'useUnicode' => false,

    // While PsySH respects the current `error_reporting` level, and doesn't throw
    // exceptions for all errors, it does log all errors regardless of level. Set
    // `errorLoggingLevel` to 0 to prevent logging non-thrown errors. Set it to any
    // valid `error_reporting` value to log only errors which match that level.
    'errorLoggingLevel' => E_ALL & ~E_NOTICE,

    // "Default includes" will be included once at the beginning of every PsySH
    // session. This is a good place to add autoloaders for your favorite
    // libraries.
    'defaultIncludes' => array(
        __DIR__ . '/include/bootstrap.php',

    // While PsySH ships with a bunch of great commands, it's possible to add
    // your own for even more awesome. Any Psy command added here will be
    // available in your Psy shell sessions.
    'commands' => array(
        // The `parse` command is a command used in the development of PsySH.
        // Given a string of PHP code, it pretty-prints the
        // [PHP Parser]( parse tree. It
        // prolly won't be super useful for most of you, but it's there if you
        // want to play :)
        new \Psy\Command\ParseCommand,

    // PsySH uses symfony/var-dumper's casters for presenting scalars, resources,
    // arrays and objects. You can enable additional casters, or write your own!
    // See
    'casters' => array(
        'MyFooClass' => 'MyFooClassCaster::castMyFooObject',

    // You can disable tab completion if you want to. Not sure why you'd want to.
    'tabCompletion' => false,

    // You can write your own tab completion matchers, too! Here are some that enable
    // tab completion for MongoDB database and collection names:
    'tabCompletionMatchers' => array(
        new \Psy\TabCompletion\Matcher\MongoClientMatcher,
        new \Psy\TabCompletion\Matcher\MongoDatabaseMatcher,

    // If multiple versions of the same configuration or data file exist, PsySH will
    // use the file with highest precedence, and will silently ignore all others. With
    // this enabled, a warning will be emitted (but not an exception thrown) if multiple
    // configuration or data files are found.
    // This will default to true in a future release, but is false for now.
    'warnOnMultipleConfigs' => true,

    // By default, output contains colors if support for them is detected. To override:
    'colorMode' => \Psy\Configuration::COLOR_MODE_FORCED,   // force colors in output
    'colorMode' => \Psy\Configuration::COLOR_MODE_DISABLED, // disable colors in output

    // Frequency of update checks when starting an interactive shell session. Valid
    // options are 'always', 'daily', 'weekly', and 'monthly'. Default is 'weekly'.
    // To disable update checks entirely, set to 'never'.
    'updateCheck' => 'daily',

    // Display an additional startup message. Default is ''.
    // You can color and style the message thanks to the Symfony Console tags.
    // See for more details.
    'startupMessage' => sprintf('<info>%s</info>', shell_exec('uptime')),