def exists(package):
    """
    Return True if package information is available.

    If ``pkg-config`` not on path, raises ``EnvironmentError``.
    """
    pkg_config_exe = os.environ.get('PKG_CONFIG', None) or 'pkg-config'
    cmd = '{0} --exists {1}'.format(pkg_config_exe, package).split()
    return call(cmd) == 0