php.txt

ini_set('display_errors', '1');
error_reporting(-1); // report everything, forever

# echo CLI errors to STDERR
fwrite(STDERR, "E: invalid input!");
# for PHP's own errors (not tested):
ini_set('display_errors', 'stderr');

# Detect whether input or output are tty. if not, it's likely pipes.

echo "input: ".(posix_isatty(STDIN) ? 'tty' : 'no tty')."\\n";
echo "output: ".(posix_isatty(STDOUT) ? 'tty' : 'no tty')."\\n";

# prompt reader for value from CLI script:
function input(string $prompt = null): string
{
    echo $prompt;
    $handle = fopen ("php://stdin","r");
    $output = fgets ($handle);
    return trim ($output);
}

# call nano from PHP CLI script, for a temp file, say
$fname = tempnam('/tmp', '');
file_put_contents($fname, "some value or variable or other file content...");

// edit the temp file, loop back if the saved content is not valid
while (1) {
    system("nano $fname > $(tty)");
    $content = file_get_contents($fname);
    // check content..
    if ($error) {
        $again = input("there were errors, want to try again? "); // input() see above
        if (! in_array($again, [yes, y, etc])) {
            break;
        }
    }else{
        file_put_contents($realFile, $content);
        break;
    }
}

unlink($fname);