An issue in installation:No such file or directory: 'python'

[lwisle]

Hello,I want to install crazyswarm in Ubuntu 20.04 with python 3.8.10. All the steps I followed are same as the part:Physical Robots and Simulation except gcc-arm-embedded in step 3.Because in Ubuntu 20.04 I can't use gcc-arm-embedded, so I followed methods in this page：https://askubuntu.com/questions/1243252/how-to-install-arm-none-eabi-gdb-on-ubuntu-20-04-lts-focal-fossa

now the arm-none-eabi version is: (GNU Arm Embedded Toolchain 10.3-2021.07) 10.3.1 20210621 (release),and the other install steps are finished.But when I verify the installation by running the unit tests, the error occurs:

E FileNotFoundError: [Errno 2] No such file or directory: 'python'
/usr/lib/python3.8/subprocess.py:1704: FileNotFoundError

============================= test session starts ==============================
platform linux -- Python 3.8.10, pytest-4.6.9, py-1.8.1, pluggy-0.13.0
rootdir: /home/lw/桌面/crazyswarm/ros_ws/src/crazyswarm/scripts
collected 30 items

test_collisionAvoidance.py ............ [ 40%]
test_highLevel.py ......... [ 70%]
test_lowLevel.py ...... [ 90%]
test_simOnly.py . [ 93%]
test_videoOutput.py F [ 96%]
test_yamlString.py . [100%]

=================================== FAILURES ===================================
_______________________________ test_videoOutput _______________________________

tmp_path = PosixPath('/tmp/pytest-of-lw/pytest-0/test_videoOutput0')

@pytest.mark.skipif("TRAVIS" in os.environ or "CI" in os.environ,
                    reason="CI usually cannot create OpenGL context.")
def test_videoOutput(tmp_path):
    # tmp_path is supplied by pytest - a directory where we can write that will
    # eventually be deleted.
    path = str(tmp_path / "crazyswarm_test_video.mp4")

  subprocess.call(["python", __file__, path])

test_videoOutput.py:64:

---

/usr/lib/python3.8/subprocess.py:340: in call
with Popen(*popenargs, **kwargs) as p:
/usr/lib/python3.8/subprocess.py:858: in init
self._execute_child(args, executable, preexec_fn, close_fds,

---

self = <subprocess.Popen object at 0x7fe77466e9a0>
args = ['python', '/home/lw/桌面/crazyswarm/ros_ws/src/crazyswarm/scripts/test_videoOutput.py', '/tmp/pytest-of-lw/pytest-0/test_videoOutput0/crazyswarm_test_video.mp4']
executable = b'python', preexec_fn = None, close_fds = True, pass_fds = ()
cwd = None, env = None, startupinfo = None, creationflags = 0, shell = False
p2cread = -1, p2cwrite = -1, c2pread = -1, c2pwrite = -1, errread = -1
errwrite = -1, restore_signals = True, start_new_session = False

def _execute_child(self, args, executable, preexec_fn, close_fds,
                   pass_fds, cwd, env,
                   startupinfo, creationflags, shell,
                   p2cread, p2cwrite,
                   c2pread, c2pwrite,
                   errread, errwrite,
                   restore_signals, start_new_session):
    """Execute program (POSIX version)"""

    if isinstance(args, (str, bytes)):
        args = [args]
    elif isinstance(args, os.PathLike):
        if shell:
            raise TypeError('path-like args is not allowed when '
                            'shell is true')
        args = [args]
    else:
        args = list(args)

    if shell:
        # On Android the default shell is at '/system/bin/sh'.
        unix_shell = ('/system/bin/sh' if
                  hasattr(sys, 'getandroidapilevel') else '/bin/sh')
        args = [unix_shell, "-c"] + args
        if executable:
            args[0] = executable

    if executable is None:
        executable = args[0]

    sys.audit("subprocess.Popen", executable, args, cwd, env)

    if (_USE_POSIX_SPAWN
            and os.path.dirname(executable)
            and preexec_fn is None
            and not close_fds
            and not pass_fds
            and cwd is None
            and (p2cread == -1 or p2cread > 2)
            and (c2pwrite == -1 or c2pwrite > 2)
            and (errwrite == -1 or errwrite > 2)
            and not start_new_session):
        self._posix_spawn(args, executable, env, restore_signals,
                          p2cread, p2cwrite,
                          c2pread, c2pwrite,
                          errread, errwrite)
        return

    orig_executable = executable

    # For transferring possible exec failure from child to parent.
    # Data format: "exception name:hex errno:description"
    # Pickle is not used; it is complex and involves memory allocation.
    errpipe_read, errpipe_write = os.pipe()
    # errpipe_write must not be in the standard io 0, 1, or 2 fd range.
    low_fds_to_close = []
    while errpipe_write < 3:
        low_fds_to_close.append(errpipe_write)
        errpipe_write = os.dup(errpipe_write)
    for low_fd in low_fds_to_close:
        os.close(low_fd)
    try:
        try:
            # We must avoid complex work that could involve
            # malloc or free in the child process to avoid
            # potential deadlocks, thus we do all this here.
            # and pass it to fork_exec()

            if env is not None:
                env_list = []
                for k, v in env.items():
                    k = os.fsencode(k)
                    if b'=' in k:
                        raise ValueError("illegal environment variable name")
                    env_list.append(k + b'=' + os.fsencode(v))
            else:
                env_list = None  # Use execv instead of execve.
            executable = os.fsencode(executable)
            if os.path.dirname(executable):
                executable_list = (executable,)
            else:
                # This matches the behavior of os._execvpe().
                executable_list = tuple(
                    os.path.join(os.fsencode(dir), executable)
                    for dir in os.get_exec_path(env))
            fds_to_keep = set(pass_fds)
            fds_to_keep.add(errpipe_write)
            self.pid = _posixsubprocess.fork_exec(
                    args, executable_list,
                    close_fds, tuple(sorted(map(int, fds_to_keep))),
                    cwd, env_list,
                    p2cread, p2cwrite, c2pread, c2pwrite,
                    errread, errwrite,
                    errpipe_read, errpipe_write,
                    restore_signals, start_new_session, preexec_fn)
            self._child_created = True
        finally:
            # be sure the FD is closed no matter what
            os.close(errpipe_write)

        self._close_pipe_fds(p2cread, p2cwrite,
                             c2pread, c2pwrite,
                             errread, errwrite)

        # Wait for exec to fail or succeed; possibly raising an
        # exception (limited in size)
        errpipe_data = bytearray()
        while True:
            part = os.read(errpipe_read, 50000)
            errpipe_data += part
            if not part or len(errpipe_data) > 50000:
                break
    finally:
        # be sure the FD is closed no matter what
        os.close(errpipe_read)

    if errpipe_data:
        try:
            pid, sts = os.waitpid(self.pid, 0)
            if pid == self.pid:
                self._handle_exitstatus(sts)
            else:
                self.returncode = sys.maxsize
        except ChildProcessError:
            pass

        try:
            exception_name, hex_errno, err_msg = (
                    errpipe_data.split(b':', 2))
            # The encoding here should match the encoding
            # written in by the subprocess implementations
            # like _posixsubprocess
            err_msg = err_msg.decode()
        except ValueError:
            exception_name = b'SubprocessError'
            hex_errno = b'0'
            err_msg = 'Bad exception data from child: {!r}'.format(
                          bytes(errpipe_data))
        child_exception_type = getattr(
                builtins, exception_name.decode('ascii'),
                SubprocessError)
        if issubclass(child_exception_type, OSError) and hex_errno:
            errno_num = int(hex_errno, 16)
            child_exec_never_called = (err_msg == "noexec")
            if child_exec_never_called:
                err_msg = ""
                # The error must be from chdir(cwd).
                err_filename = cwd
            else:
                err_filename = orig_executable
            if errno_num != 0:
                err_msg = os.strerror(errno_num)

          raise child_exception_type(errno_num, err_msg, err_filename)

E FileNotFoundError: [Errno 2] No such file or directory: 'python'

/usr/lib/python3.8/subprocess.py:1704: FileNotFoundError
===================== 1 failed, 29 passed in 3.28 seconds ======================

I don't know how to fix it now.All times I tryed, this error occured.
thanks for your advice

[jpreiss]

you can ignore this failure. I believe the test should be running $CSW_PYTHON in a shell subprocess instead of just python.

[lwisle]

thank you