How to use the sh.grep function in sh

def resolve_ip(ip):
    from sh import grep

    if ip_hostname_cache.get(ip):
        return ip_hostname_cache[ip]
    hostname = ip
    # tricky
    if ip.startswith('192.') or ip.startswith('10.'):
        hosts_files = (HOSTS_FILE,)
    else:
        hosts_files = (HOSTS_WAN_FILE,)
    for hosts_file in hosts_files:
        try:
            out = grep('^[^#]*%s[^0-9]' % ip, hosts_file, E=True)
            if out:
                hostname = out.split()[-1]
                break
        except Exception:
            pass
    ip_hostname_cache[ip] = hostname
    return hostname

def parse_memory_usage(self):
        """
        Parse memory usage information.
        """
        st = sh.grep(sh.sysctl('-a'), 'mem')
        vm = sh.vm_stat()
        pattern = re.compile(':[\s]+')
        st_lines = st.split('\n')
        st_rows = dict()
        for line in st_lines:
            t = line.strip()
            if t:
                row = pattern.split(t)
                st_rows[row[0]] = int(row[1])
        vm_lines = vm.split('\n')
        vm_rows = dict()
        for i, line in enumerate(vm_lines):
            # ignore header
            if i == 0:
                continue
            t = line.strip()

def remote_url(git, remote, original="origin"):
    origin_url = sh.grep(git.remote("-v"), original).split()[1]
    repo_name = origin_url.rsplit("/", 1)[1]
    return "https://github.com/{}/{}".format(remote, repo_name)

def __init__(self):
      """Loads dynamic libraries"""

      try:
          if 'LIBCASM' in os.environ:
              libcasm_path = os.environ['LIBCASM']
          else:
              casm_path = find_executable('ccasm')
              if platform == 'darwin':
                  libcasm_path = sh.grep(sh.otool('-L', casm_path), 'libcasm').split()[0]
                  libcasm_path = libcasm_path.replace('@loader_path', dirname(casm_path))
              else:
                  libcasm_path = sh.grep(sh.ldd(casm_path), 'libcasm').split()[2]
          libccasm_path = libcasm_path.replace('libcasm', 'libccasm')

          self.lib_casm = ctypes.CDLL(libcasm_path, mode=ctypes.RTLD_GLOBAL)
          self.lib_ccasm = ctypes.CDLL(libccasm_path, mode=ctypes.RTLD_GLOBAL)
      except Exception as e:
          print("\n~~~ Error loading casm libraries ~~~")
          if 'LIBCASM' in os.environ:
              libcasm_path = os.environ['LIBCASM']
              print("Looking for libcasm at LIBCASM:", libcasm_path)
              if not os.path.exists(libcasm_path):
                  print("File does not exist")
                  print("Install CASM if it is not installed, or update your PATH, or set LIBCASM to the location of libcasm.")
              else:

def is_routing_up():
    try:
        sh.grep(sh.route(), 'default')
        return True
    except sh.ErrorReturnCode_1:
        return False

def check_upgrade():
        server_file = curl(PIFM_HOST + '/client_agent/pifm_agent.py')
        server_sum = awk(
                        md5sum(
                            grep(server_file, '-v', '^PIFM_HOST')
                        ), '{print $1}'
        )

        local_sum = awk(
                        md5sum(
                            grep('-v', '^PIFM_HOST', OUR_SCRIPT)
                        ), '{print $1}'
        )

        if str(server_sum) != str(local_sum):
            logging.info(
                "server: {server}, local: {local}, should update.".format(
                    server=server_sum,
                    local=local_sum
                )
            )

def adb_devices():
  outputs = sh.grep(sh.adb("devices"), "^[A-Za-z0-9]\+[[:space:]]\+device$")
  raw_lists = sh.cut(outputs, "-f1")
  return adb_split_stdout(raw_lists)

def check_if_package_is_installed(self, package):
        """checks if a package is installed

        :param string package: package name to check
        :rtype: `bool` representing whether package is installed or not
        """

        lgr.debug('Checking if {0} is installed'.format(package))
        r = sh.grep(sh.rpm('-qa', _ok_code=[0, 1]), package)
        if r.exit_code == 0:
            lgr.debug('{0} is installed'.format(package))
            return True
        else:
            lgr.error('{0} is not installed'.format(package))
            return False