Run command when any file in working directory changes (recursive check)

watch-tree

#!/usr/bin/env php
<?php

declare(strict_types = 1);

namespace Scripts;

// run given command when any file changes in given paths or in working directory

if (!isset($_SERVER['argv'][1])) {
	fwrite(STDOUT, 'Usage:
	' . basename(__FILE__) . ' [<path_1=cwd> [, <path_2>, ...]] <command>' . "\n");

	exit(1);
}

(static function (): void {

	$cwd = getcwd();
	$paths = array_slice($_SERVER['argv'], 1);
	$command = array_pop($paths);

	if ($paths === []) {
		$paths[] = '';
	}

	$treeHashCalculator = static function () use ($paths, $cwd): string {
		$cmd = sprintf(
			'find %s -type f -not -path "*/\.*" -print0 | xargs -0 sha1sum | sha1sum 2>&1', // do not check dot-files
			implode(' ', array_map(static function (string $path) use ($cwd): string {
				// prepend cwd for relative paths
				$fullPath = strpos($path, '/') !== 0 && strpos($path, ':') === false
					? rtrim(sprintf('%s/%s', $cwd, $path), '/\\')
					: $path;

				return escapeshellarg($fullPath);

			}, $paths)),
		);

		$status = 0;
		$output = [];
		exec($cmd, $output, $status);

		if ($status !== 0) {
			fwrite(STDERR, '[wt] Cannot calculate content checksum - ' . implode("\n", $output) . "\n");
			exit(1);
		}

		return trim(implode('', $output));
	};

	$changed = false;
	$treeHash = null;

	while (true) {
		if ($treeHash === null) {
			fwrite(STDOUT, '[wt] Calculating initial checksum ...');
		}

		$freshTreeHash = $treeHashCalculator();

		if ($treeHash === null) {
			fwrite(STDOUT, ' OK (' . $freshTreeHash . ')' . "\n");

		} elseif ($treeHash !== $freshTreeHash) {
			fwrite(STDOUT, '[wt] Change detected (' . $freshTreeHash . ') - running "' . $command . '" ...' . "\n\n");

			$start = time();
			passthru(escapeshellcmd($command));
			fwrite(STDOUT, "\n" . '[wt] Done in ' . time() - $start . 's' . "\n");

			$changed = true;

		} else {
			$changed = false;
		}

		if ($changed || $treeHash === null) { // message on first run or after change
			fwrite(STDOUT, '[wt] Watching for changes in "' . ($paths === [''] ? $cwd : implode('", "', $paths)) . '" ...' . "\n");
		}

		$treeHash = $freshTreeHash;
		usleep(500000); // 0.5s
	}

})();

Example usage:

watch-tree "composer dump-autoload"