``ftputil`` -- a high-level FTP client library ============================================== :Version: 4.0.0 :Date: 2020-06-13 :Summary: high-level FTP client library for Python :Keywords: FTP, ``ftplib`` substitute, virtual filesystem, pure Python :Author: Stefan Schwarzer .. contents:: Introduction ------------ The ``ftputil`` module is a high-level interface to the ftplib_ module. The `FTPHost objects`_ generated from it allow many operations similar to those of os_, `os.path`_ and `shutil`_. .. _ftplib: https://docs.python.org/library/ftplib.html .. _os: https://docs.python.org/library/os.html .. _`os.stat`: https://docs.python.org/library/os.html#os.stat .. _`os.path`: https://docs.python.org/library/os.path.html .. _`shutil`: https://docs.python.org/library/shutil.html Example:: import ftputil # Download some files from the login directory. with ftputil.FTPHost("ftp.domain.com", "user", "password") as ftp_host: names = ftp_host.listdir(ftp_host.curdir) for name in names: if ftp_host.path.isfile(name): ftp_host.download(name, name) # remote, local # Make a new directory and copy a remote file into it. ftp_host.mkdir("newdir") with ftp_host.open("index.html", "rb") as source: with ftp_host.open("newdir/index.html", "wb") as target: ftp_host.copyfileobj(source, target) # similar to shutil.copyfileobj Also, there are `FTPHost.lstat`_ and `FTPHost.stat`_ to request size and modification time of a file. The latter can also follow links, similar to `os.stat`_. `FTPHost.walk`_ and `FTPHost.path.walk`_ work, too. ``ftputil`` features -------------------- * Method names are familiar from Python's ``os``, ``os.path`` and ``shutil`` modules. For example, use ``os.path.join`` to join paths for a local file system and ``ftp_host.path.join`` to join paths for a remote FTP file system. * Remote file system navigation (``getcwd``, ``chdir``) * Upload and download files (``upload``, ``upload_if_newer``, ``download``, ``download_if_newer``) * Time zone synchronization between client and server (needed for ``upload_if_newer`` and ``download_if_newer``) * Create and remove directories (``mkdir``, ``makedirs``, ``rmdir``, ``rmtree``) and remove files (``remove``) * Get information about directories, files and links (``listdir``, ``stat``, ``lstat``, ``exists``, ``isdir``, ``isfile``, ``islink``, ``abspath``, ``dirname``, ``basename`` etc.) * Iterate over remote file systems (``walk``) * Local caching of results from ``lstat`` and ``stat`` calls to reduce network access (also applies to ``exists``, ``getmtime`` etc.). * Read files from and write files to remote hosts via file-like objects (``FTPHost.open``; the generated file-like objects have the familiar methods like ``read``, ``readline``, ``readlines``, ``write``, ``writelines`` and ``close``. You can also iterate over these files line by line in a ``for`` loop. Exception hierarchy ------------------- The exceptions are in the namespace of the ``ftputil.error`` module, e. g. ``ftputil.error.TemporaryError``. The exception classes are organized as follows:: FTPError FTPOSError(FTPError, OSError) PermanentError(FTPOSError) CommandNotImplementedError(PermanentError) TemporaryError(FTPOSError) FTPIOError(FTPError) InternalError(FTPError) InaccessibleLoginDirError(InternalError) ParserError(InternalError) RootDirError(InternalError) TimeShiftError(InternalError) and are described here: - ``FTPError`` is the root of the exception hierarchy of the module. - ``FTPOSError`` is derived from ``OSError``. This is for similarity between the os module and ``FTPHost`` objects. Compare :: try: os.chdir("nonexisting_directory") except OSError: ... with :: host = ftputil.FTPHost("host", "user", "password") try: host.chdir("nonexisting_directory") except OSError: ... Imagine a function :: def func(path, file): ... which works on the local file system and catches ``OSErrors``. If you change the parameter list to :: def func(path, file, os=os): ... where ``os`` denotes the ``os`` module, you can call the function also as :: host = ftputil.FTPHost("host", "user", "password") func(path, file, os=host) to use the same code for both a local and remote file system. Another similarity between ``OSError`` and ``FTPOSError`` is that the latter holds the FTP server return code in the ``errno`` attribute of the exception object and the error text in ``strerror``. - ``PermanentError`` is raised for 5xx return codes from the FTP server. This corresponds to ``ftplib.error_perm`` (though ``PermanentError`` and ``ftplib.error_perm`` are *not* identical). - ``CommandNotImplementedError`` indicates that an underlying command the code tries to use is not implemented. For an example, see the description of the `FTPHost.chmod`_ method. - ``TemporaryError`` is raised for FTP return codes from the 4xx category. This corresponds to ``ftplib.error_temp`` (though ``TemporaryError`` and ``ftplib.error_temp`` are *not* identical). - ``FTPIOError`` denotes an I/O error on the remote host. This appears mainly with file-like objects that are retrieved by calling ``FTPHost.open``. Compare :: >>> try: ... f = open("not_there") ... except IOError as obj: ... print(obj.errno) ... print(obj.strerror) ... 2 No such file or directory with :: >>> ftp_host = ftputil.FTPHost("host", "user", "password") >>> try: ... f = ftp_host.open("not_there") ... except IOError as obj: ... print(obj.errno) ... print(obj.strerror) ... 550 550 not_there: No such file or directory. As you can see, both code snippets are similar. However, the error codes aren't the same. - ``InternalError`` subsumes exception classes for signaling errors due to limitations of the FTP protocol or the concrete implementation of ``ftputil``. - ``InaccessibleLoginDirError`` This exception is raised if the directory in which "you" are placed upon login is not accessible, i. e. a ``chdir`` call with the directory as argument would fail. - ``ParserError`` is used for errors during the parsing of directory listings from the server. This exception is used by the ``FTPHost`` methods ``stat``, ``lstat``, and ``listdir``. - ``RootDirError`` Because of the implementation of the ``lstat`` method it is not possible to do a ``stat`` call on the root directory ``/``. If you know *any* way to do it, please let me know. :-) This problem does *not* affect stat calls on items *in* the root directory. - ``TimeShiftError`` is used to denote errors which relate to setting the `time shift`_. Directory and file names ------------------------ .. note:: Keep in mind that this section only applies to directory and file *names*, not file *contents*. Encoding and decoding for file contents is handled by the ``encoding`` argument for `FTPHost.open`_. First off: If your directory and file names (both as arguments and on the server) contain only ISO 8859-1 (latin-1) characters, you can use such names in the form of ``bytes`` or ``str`` objects. However, you can't mix different string types (``bytes`` and ``str``) in one call (for example in ``FTPHost.path.join``). If you have directory or file names with characters that aren't in latin-1, it's recommended to use ``bytes`` objects. In that case, returned paths will be ``bytes`` objects, too. Read on for details. .. note:: The approach described below may look awkward and in a way it is. The intention of ``ftputil`` is to behave like the local file system APIs of Python 3 as far as it makes sense. Moreover, the taken approach makes sure that directory and file names that were used with Python 3's native ``ftplib`` module will be compatible with ``ftputil`` and vice versa. Otherwise you may be able to use a file name with ``ftputil``, but get an exception when trying to read the same file with Python 3's ``ftplib`` module. Methods that take paths of directories and/or files can take either ``bytes`` or ``str`` objects, or `PathLike`_ objects that can be converted to ``bytes`` or ``str``. .. _PathLike: https://docs.python.org/3/library/os.html#os.PathLike If a method gets a string argument (or a string argument wrapped in a PathLike_ object) and returns one or more strings, these strings will have the same string type (``bytes`` or ``str``) as the argument(s). Mixing different string types in one call (for example in ``FTPHost.path.join``) isn't allowed and will cause a ``TypeError``. These rules are the same as for local file system operations in Python 3. ``bytes`` objects for directory and file names will be sent to the server as-is. On the other hand, ``str`` objects will be encoded to ``bytes`` objects, assuming latin-1 encoding. This implies that such ``str`` objects must only contain code points 0-255 for the latin-1 character set. Using any other characters will result in a ``UnicodeEncodeError`` exception. If you have directory or file names as ``str`` objects with non-latin-1 characters, encode the strings to ``bytes`` yourself, using the encoding you know the server uses for its file system. Decode received paths with the same encoding. Encapsulate these conversions as far as you can. Otherwise, you'd have to adapt potentially a lot of code if the server encoding changes. If you *don't* know the encoding on the server side, it's probably the best to only use ``bytes`` for directory and file names. That said, as soon as you *show* the names to a user, you -- or the library you use for displaying the names -- has to guess an encoding. If you can decide about paths yourself, it's generally safest to use only ASCII characters in FTP paths. ``FTPHost`` objects ------------------- .. _`FTPHost construction`: Construction ~~~~~~~~~~~~ Introduction ```````````` ``FTPHost`` instances can be created with the following call:: ftp_host = ftputil.FTPHost(server, user, password, account, session_factory=ftplib.FTP) The first four parameters are strings with the same meaning as for the FTP class in the ``ftplib`` module. Usually the ``account`` and ``session_factory`` arguments aren't needed though. ``FTPHost`` objects can also be used in a ``with`` statement:: import ftputil with ftputil.FTPHost(server, user, password) as ftp_host: print(ftp_host.listdir(ftp_host.curdir)) After the ``with`` block, the ``FTPHost`` instance and the associated FTP sessions will be closed automatically. If something goes wrong during the ``FTPHost`` construction or in the body of the ``with`` statement, the instance is closed as well. Exceptions will be propagated (as with ``try ... finally``). Session factories ````````````````` The keyword argument ``session_factory`` may be used to generate FTP connections with other factories than the default ``ftplib.FTP``. For example, the standard library of Python 3 contains a class ``ftplib.FTP_TLS`` which extends ``ftplib.FTP`` to use an encrypted connection. In fact, all positional and keyword arguments other than ``session_factory`` are passed to the factory to generate a new background session. This also happens for every remote file that is opened; see below. This functionality of the constructor also allows to wrap ``ftplib.FTP`` objects to do something that wouldn't be possible with the ``ftplib.FTP`` constructor alone. As an example, assume you want to connect to another than the default port, but ``ftplib.FTP`` only offers this by means of its ``connect`` method, not via its constructor. One solution is to use a custom class as a session factory:: import ftplib import ftputil EXAMPLE_PORT = 50001 class MySession(ftplib.FTP): def __init__(self, host, userid, password, port): """Act like ftplib.FTP's constructor but connect to another port.""" ftplib.FTP.__init__(self) self.connect(host, port) self.login(userid, password) # Try _not_ to use an _instance_ `MySession()` as factory, - # use the class itself. with ftputil.FTPHost(host, userid, password, port=EXAMPLE_PORT, session_factory=MySession) as ftp_host: # Use `ftp_host` as usual. ... On login, the format of the directory listings (needed for stat'ing files and directories) should be determined automatically. If not, please `enter a ticket`_. .. _`enter a ticket`: https://ftputil.sschwarzer.net/issuetrackernotes For the most common uses you don't need to create your own session factory class though. The ``ftputil.session`` module has a function ``session_factory`` that can create session factories for a variety of parameters:: session_factory(base_class=ftplib.FTP, port=21, use_passive_mode=None, encrypt_data_channel=True, debug_level=None) with - ``base_class`` is a base class to inherit a new session factory class from. By default, this is ``ftplib.FTP`` from the Python standard library. - ``port`` is the command channel port. The default is 21, used in most FTP server configurations. - ``use_passive_mode`` is either a boolean that determines whether passive mode should be used or ``None``. ``None`` means to let the base class choose active or passive mode. - ``encrypt_data_channel`` defines whether to encrypt the data channel for secure connections. This is only supported for the base classes ``ftplib.FTP_TLS`` and ``M2Crypto.ftpslib.FTP_TLS``, otherwise the parameter is ignored. - ``debug_level`` sets the debug level for FTP session instances. The semantics is defined by the base class. For example, a debug level of 2 causes the most verbose output for Python's ``ftplib.FTP`` class. All of these parameters can be combined. For example, you could use :: import ftplib import ftputil import ftputil.session my_session_factory = ftputil.session.session_factory( base_class=ftpslib.FTP_TLS, port=31, encrypt_data_channel=True, debug_level=2) with ftputil.FTPHost(server, user, password, session_factory=my_session_factory) as ftp_host: ... to create and use a session factory derived from ``ftplib.FTP_TLS`` that connects on command channel 31, will encrypt the data channel and print output for debug level 2. Note: Generally, you can achieve everything you can do with ``ftputil.session.session_factory`` with an explicit session factory as described at the start of this section. However, the class ``M2Crypto.ftpslib.FTP_TLS`` has a limitation so that you can't use it with ftputil out of the box. The function ``session_factory`` contains a workaround for this limitation. For details refer to `this ticket`_. .. _`this ticket`: https://ftputil.sschwarzer.net/trac/ticket/78 Hidden files and directories ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Whether ftputil sees "hidden" files and directories (usually files or directories whose names start with a dot) depends on the FTP server configuration. By default, ftputil does *not* use the ``-a`` option in the FTP ``LIST`` command to find hidden files. To tell the server to list hidden directories and files, set ``FTPHost.use_list_a_option`` to ``True``:: ftp_host = ftputil.FTPHost(server, user, password, account, session_factory=ftplib.FTP) ftp_host.use_list_a_option = True Caveats: - If the server doesn't understand the ``-a`` option at all, the server may interpret ``-a`` as the name of a file or directory, which can result in odd behavior. Therefore, use ``-a`` only if you're sure the server you're talking to supports it. Another approach is to have test code for ``-a`` support and fall back to not using the option. - Even if the server knows about the ``-a`` option, the server may be configured to ignore it. ``FTPHost`` attributes and methods ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Attributes `````````` - ``curdir``, ``pardir``, ``sep`` are strings which denote the current and the parent directory on the remote server. ``sep`` holds the path separator. Though `RFC 959`_ (File Transfer Protocol) notes that these values may depend on the FTP server implementation, the Unix variants seem to work well in practice, even for non-Unix servers. Nevertheless, it's recommended that you don't hardcode these values for remote paths, but use `FTPHost.path`_ as you would use ``os.path`` to write platform-independent Python code for local filesystems. Keep in mind that most, *but not all*, arguments of ``FTPHost`` methods refer to remote directories or files. For example, in `FTPHost.upload`_, the first argument is a local path and the second a remote path. Both of these should use their respective path separators. .. _`FTPHost.upload`: `Uploading and downloading files`_ Remote file system navigation ````````````````````````````` - ``getcwd()`` returns the absolute current directory on the remote host. This method works like ``os.getcwd``. - ``chdir(directory)`` sets the current directory on the FTP server. This resembles ``os.chdir``, as you may have expected. .. _`callback function`: Uploading and downloading files ``````````````````````````````` - ``upload(source, target, callback=None)`` copies a local source file (given by a filename, i. e. a string) to the remote host under the name target. Both ``source`` and ``target`` may be absolute paths or relative to their corresponding current directory (on the local or the remote host, respectively). The file content is always transferred in binary mode. The callback, if given, will be invoked for each transferred chunk of data:: callback(chunk) where ``chunk`` is a bytestring. An example usage of a callback method is to display a progress indicator. - ``download(source, target, callback=None)`` performs a download from the remote source file to a local target file. Both ``source`` and ``target`` are strings. See the description of ``upload`` for more details. .. _`upload_if_newer`: - ``upload_if_newer(source, target, callback=None)`` is similar to the ``upload`` method. The only difference is that the upload is only invoked if the time of the last modification for the source file is more recent than that of the target file or the target doesn't exist at all. The check for the last modification time considers the precision of the timestamps and transfers a file "if in doubt". Consequently the code :: ftp_host.upload_if_newer("source_file", "target_file") time.sleep(10) ftp_host.upload_if_newer("source_file", "target_file") might upload the file again if the timestamp of the target file is precise up to a minute, which is typically the case because the remote datetime is determined by parsing a directory listing from the server. To avoid unnecessary transfers, wait at least a minute between calls of ``upload_if_newer`` for the same file. If it still seems that a file is uploaded unnecessarily (or not when it should), read the subsection on `time shift`_ settings. If an upload actually happened, the return value of ``upload_if_newer`` is a ``True``, else ``False``. Note that the method only checks the existence and/or the modification time of the source and target file; it doesn't compare any other file properties, say, the file size. This also means that if a transfer is interrupted, the remote file will have a newer modification time than the local file, and thus the transfer won't be repeated if ``upload_if_newer`` is used a second time. There are at least two possibilities after a failed upload: - use ``upload`` instead of ``upload_if_newer``, or - remove the incomplete target file with ``FTPHost.remove``, then use ``upload`` or ``upload_if_newer`` to transfer it again. .. _`download_if_newer`: - ``download_if_newer(source, target, callback=None)`` corresponds to ``upload_if_newer`` but performs a download from the server to the local host. Read the descriptions of download and ``upload_if_newer`` for more information. If a download actually happened, the return value is ``True``, else ``False``. .. _`time shift`: .. _`time zone correction`: Time zone correction ```````````````````` For ``upload_if_newer`` and ``download_if_newer`` to work correctly, the time zone of the server must be taken into account. By default, ftputil assumes that the timestamps in server listings are in UTC_. .. _UTC: https://en.wikipedia.org/wiki/Utc .. _`set_time_shift`: - ``set_time_shift(time_shift)`` sets the so-called time shift value, measured in seconds. The time shift here is defined as the difference between the time used in server listings and UTC. :: time_shift = server_time - utc_time For example, a server in Berlin/Germany set to the local time (currently UTC+03:00), would require a time shift value of 3 * 3600.0 = 10800.0 seconds to be handled correctly by ftputil's ``upload_if_newer`` and ``download_if_newer``, as well as the ``stat`` and ``lstat`` calls. Note that servers don't necessarily send their file system listings in their local time zone. Some use UTC, which actually makes sense because UTC doesn't lead to an ambiguity when there's a switch back from the daylight saving time to the "normal" time of the server location. If the time shift value is invalid, for example its absolute value is larger than 24 hours, a ``TimeShiftError`` is raised. .. note:: Versions of ftputil before 4.0.0 used a different definition of "time shift", server_time - local_client_time. This had the advantage that the default of 0.0 would be correct *if* the server was set to the same time zone as the client where ftputil runs. On the other hand, this approach meant that the time shift depended on *two* time zones, not only the one used on the server side. This could be confusing if server and client *didn't* use the same time zone. See also `synchronize_times`_ for a way to set the time shift with a simple method call. If you can't use ``synchronize_times`` *and* the server uses the same time zone as the client, you can set the time shift value with :: set_time_shift( round( (datetime.datetime.now() - datetime.datetime.utcnow()).seconds, -2 ) ) - ``time_shift()`` returns the currently-set time shift value. See ``set_time_shift`` above for its definition. .. _`synchronize_times`: - ``synchronize_times()`` synchronizes the local times of the server and the client, so that `upload_if_newer`_ and `download_if_newer`_ work as expected, even if the client and the server use different time zones. For this to work, *all* of the following conditions must be true: - The connection between server and client is established. - The client has write access to the directory that is current when ``synchronize_times`` is called. If you can't fulfill these conditions, you can nevertheless set the time shift value explicitly with `set_time_shift`_. Trying to call ``synchronize_times`` if the above conditions aren't met results in a ``TimeShiftError`` exception. Creating and removing directories ````````````````````````````````` - ``mkdir(path, [mode])`` makes the given directory on the remote host. This does *not* construct "intermediate" directories that don't already exist. The ``mode`` parameter is ignored; this is for compatibility with ``os.mkdir`` if an ``FTPHost`` object is passed into a function instead of the ``os`` module. See the explanation in the subsection `Exception hierarchy`_. - ``makedirs(path, [mode], exist_ok=False)`` works similar to ``mkdir`` (see above), but also makes intermediate directories like ``os.makedirs``. The ``mode`` parameter is only there for compatibility with ``os.makedirs`` and is ignored. ``exist_ok`` controls whether the existence of any directory but the last in the ``path`` should be considered an error. If the default ``False`` is used or passed to ``makedirs``, ftputil will raise a ``PermanentError`` if any directory but the last already exists. - ``rmdir(path)`` removes the given remote directory. If it's not empty, raise a ``PermanentError``. - ``rmtree(path, ignore_errors=False, onerror=None)`` removes the given remote, possibly non-empty, directory tree. The interface of this method is rather complex, in favor of compatibility with ``shutil.rmtree``. If ``ignore_errors`` is set to a true value, errors are ignored. If ``ignore_errors`` is a false value *and* ``onerror`` isn't set, all exceptions occurring during the tree iteration and processing are raised. These exceptions are all of type ``PermanentError``. To distinguish between different kinds of errors, pass in a callable for ``onerror``. This callable must accept three arguments: ``func``, ``path`` and ``exc_info``. ``func`` is a bound method object, *for example* ``your_host_object.listdir``. ``path`` is the path that was the recent argument of the respective method (``listdir``, ``remove``, ``rmdir``). ``exc_info`` is the exception info as it is gotten from ``sys.exc_info``. The code of ``rmtree`` is taken from Python's ``shutil`` module and adapted for ``ftputil``. Removing files and links ```````````````````````` - ``remove(path)`` removes a file or link on the remote host, similar to ``os.remove``. - ``unlink(path)`` is an alias for ``remove``. Retrieving information about directories, files and links ````````````````````````````````````````````````````````` - ``listdir(path)`` returns a list containing the names of the files and directories in the given path, similar to `os.listdir`_. The special names ``.`` and ``..`` are not in the list. The methods ``lstat`` and ``stat`` (and some others) rely on the directory listing format used by the FTP server. When connecting to a host, ``FTPHost``'s constructor tries to guess the right format, which succeeds in most cases. However, if you get strange results or ``ParserError`` exceptions by a mere ``lstat`` call, please `enter a ticket`_. If ``lstat`` or ``stat`` give wrong modification dates or times, look at the methods that deal with time zone differences (`time zone correction`_). .. _`FTPHost.lstat`: - ``lstat(path)`` returns an object similar to that from `os.lstat`_. This is a kind of tuple with additional attributes; see the documentation of the ``os`` module for details. The result is derived by parsing the output of a ``LIST`` command on the server. Therefore, the result from ``FTPHost.lstat`` can not contain more information than the received text. In particular: - User and group ids can only be determined as strings, not as numbers, and that only if the server supplies them. This is usually the case with Unix servers but maybe not for other FTP servers. - Values for the time of the last modification may be rough, depending on the information from the server. For timestamps older than a year, this usually means that the precision of the modification timestamp value is not better than a day. For newer files, the information may be accurate to a minute. If the time of the last modification is before the epoch (usually 1970-01-01 UTC), set the time of the last modification to 0.0. - Links can only be recognized on servers that provide this information in the ``LIST`` output. - Stat attributes that can't be determined at all are set to ``None``. For example, a line of a directory listing may not contain the date/time of a directory's last modification. - There's a special problem with stat'ing the root directory. (Stat'ing things *in* the root directory is fine though.) In this case, a ``RootDirError`` is raised. This has to do with the algorithm used by ``(l)stat``, and I know of no approach which mends this problem. Currently, ``ftputil`` recognizes the common Unix-style and Microsoft/DOS-style directory formats. If you need to parse output from another server type, please write to the `ftputil mailing list`_. You may consider `writing your own parser`_. .. _`os.listdir`: https://docs.python.org/library/os.html#os.listdir .. _`os.lstat`: https://docs.python.org/library/os.html#os.lstat .. _`ftputil mailing list`: https://ftputil.sschwarzer.net/mailinglist .. _`writing your own parser`: `Writing directory parsers`_ .. _`FTPHost.stat`: - ``stat(path)`` returns ``stat`` information also for files which are pointed to by a link. This method follows multiple links until a regular file or directory is found. If an infinite link chain is encountered or the target of the last link in the chain doesn't exist, a ``PermanentError`` is raised. The limitations of the ``lstat`` method also apply to ``stat``. .. _`FTPHost.path`: ``FTPHost`` objects contain an attribute named ``path``, similar to `os.path`_. The following methods can be applied to the remote host with the same semantics as for ``os.path``: :: abspath(path) basename(path) commonprefix(path_list) dirname(path) exists(path) getmtime(path) getsize(path) isabs(path) isdir(path) isfile(path) islink(path) join(path1, path2, ...) normcase(path) normpath(path) split(path) splitdrive(path) splitext(path) walk(path, func, arg) Like Python's counterparts under `os.path`_, ``ftputil``'s ``is...`` methods return ``False`` if they can't find the path given by their argument. Local caching of file system information ```````````````````````````````````````` Many of the above methods need access to the remote file system to obtain data on directories and files. To get the most recent data, *each* call to ``lstat``, ``stat``, ``exists``, ``getmtime`` etc. would require to fetch a directory listing from the server, which can make the program *very* slow. This effect is more pronounced for operations which mostly scan the file system rather than transferring file data. For this reason, ``ftputil`` by default saves the results from directory listings locally and reuses those results. This reduces network accesses and so speeds up the software a lot. However, since data is more rarely fetched from the server, the risk of obsolete data also increases. This will be discussed below. Caching can be controlled -- if necessary at all -- via the ``stat_cache`` object in an ``FTPHost``'s namespace. For example, after calling :: ftp_host = ftputil.FTPHost(host, user, password) the cache can be accessed as ``ftp_host.stat_cache``. While ``ftputil`` usually manages the cache quite well, there are two possible reasons for modifying cache parameters. The first is when the number of possible entries is too low. You may notice that when you are processing very large directories and the program becomes much slower than before. It's common for code to read a directory with ``listdir`` and then process the found directories and files. This can also happen implicitly by a call to ``FTPHost.walk``. Since version 2.6 ``ftputil`` automatically increases the cache size if directories with more entries than the current maximum cache size are to be scanned. Most of the time, this works fine. However, if you need access to stat data for several directories at the same time, you may need to increase the cache explicitly. This is done by the ``resize`` method:: ftp_host.stat_cache.resize(20000) where the argument is the maximum number of ``lstat`` results to store (the default is 5000, in versions before 2.6 it was 1000). Note that each path on the server, e. g. "/home/schwa/some_dir", corresponds to a single cache entry. Methods like ``exists`` or ``getmtime`` all derive their results from a previously fetched ``lstat`` result. The value 5000 above means that the cache will hold *at most* 5000 entries (unless increased automatically by an explicit or implicit ``listdir`` call, see above). If more are about to be stored, the entries which haven't been used for the longest time will be deleted to make place for newer entries. The second possible reason to change the cache parameters is to avoid stale cache data. Caching is so effective because it reduces network accesses. This can also be a disadvantage if the file system data on the remote server changes after a stat result has been retrieved; the client, when looking at the cached stat data, will use obsolete information. There are two potential ways to get such out-of-date stat data. The first happens when an ``FTPHost`` instance modifies a file path for which it has a cache entry, e. g. by calling ``remove`` or ``rmdir``. Such changes are handled transparently; the path will be deleted from the cache. A different matter are changes unknown to the ``FTPHost`` object which inspects its cache. Obviously, for example, these are changes by programs running on the remote host. On the other hand, cache inconsistencies can also occur if two ``FTPHost`` objects change a file system simultaneously:: with ( ftputil.FTPHost(server, user1, password1) as ftp_host1, ftputil.FTPHost(server, user1, password1) as ftp_host2 ): stat_result1 = ftp_host1.stat("some_file") stat_result2 = ftp_host2.stat("some_file") ftp_host2.remove("some_file") # `ftp_host1` will still see the obsolete cache entry! print(ftp_host1.stat("some_file")) # Will raise an exception since an `FTPHost` object # knows of its own changes. print(ftp_host2.stat("some_file")) At first sight, it may appear to be a good idea to have a shared cache among several ``FTPHost`` objects. After some thinking, this turns out to be very error-prone. For example, it won't help with different processes using ``ftputil``. So, if you have to deal with concurrent write/read accesses to a server, you have to handle them explicitly. The most useful tool for this is the ``invalidate`` method. In the example above, it could be used like this:: with ( ftputil.FTPHost(server, user1, password1) as ftp_host1, ftputil.FTPHost(server, user1, password1) as ftp_host2 ): stat_result1 = ftp_host1.stat("some_file") stat_result2 = ftp_host2.stat("some_file") ftp_host2.remove("some_file") # Invalidate using an absolute path. absolute_path = ftp_host1.path.abspath( ftp_host1.path.join(ftp_host1.getcwd(), "some_file")) ftp_host1.stat_cache.invalidate(absolute_path) # Will now raise an exception as it should. print(ftp_host1.stat("some_file")) # Would raise an exception since an `FTPHost` object # knows of its own changes, even without `invalidate`. print(ftp_host2.stat("some_file")) The method ``invalidate`` can be used on any *absolute* path, be it a directory, a file or a link. By default, the cache entries (if not replaced by newer ones) are stored for an infinite time. That is, if you start your Python process using ``ftputil`` and let it run for three days a stat call may still access cache data that old. To avoid this, you can set the ``max_age`` attribute:: with ftputil.FTPHost(server, user, password) as ftp_host: ftp_host.stat_cache.max_age = 60 * 60 # = 3600 seconds This sets the maximum age of entries in the cache to an hour. This means any entry older won't be retrieved from the cache but its data instead fetched again from the remote host and then again stored for up to an hour. To reset `max_age` to the default of unlimited age, i. e. cache entries never expire, use ``None`` as value. If you are certain that the cache will be in the way, you can disable and later re-enable it completely with ``disable`` and ``enable``:: with ftputil.FTPHost(server, user, password) as ftp_host: ftp_host.stat_cache.disable() ... ftp_host.stat_cache.enable() During that time, the cache won't be used; all data will be fetched from the network. After enabling the cache again, its entries will be the same as when the cache was disabled, that is, entries won't get updated with newer data during this period. Note that even when the cache is disabled, the file system data in the code can become inconsistent:: with ftputil.FTPHost(server, user, password) as ftp_host: ftp_host.stat_cache.disable() if ftp_host.path.exists("some_file"): mtime = ftp_host.path.getmtime("some_file") In that case, the file ``some_file`` may have been removed by another process between the calls to ``exists`` and ``getmtime``! Iteration over directories `````````````````````````` .. _`FTPHost.walk`: - ``walk(top, topdown=True, onerror=None, followlinks=False)`` iterates over a directory tree, similar to `os.walk`_. Actually, ``FTPHost.walk`` uses the code from Python with just the necessary modifications, so see the linked documentation. .. _`os.walk`: https://docs.python.org/2/library/os.html#os.walk .. _`FTPHost.path.walk`: - ``path.walk(path, func, arg)`` Similar to ``os.path.walk``, the ``walk`` method in `FTPHost.path`_ can be used, though ``FTPHost.walk`` is probably easier to use. Other methods ````````````` - ``close()`` closes the connection to the remote host. After this, no more interaction with the FTP server is possible with this ``FTPHost`` object. Usually you don't need to close an ``FTPHost`` instance with ``close`` if you set up the instance in a ``with`` statement. - ``rename(source, target)`` renames the source file (or directory) on the FTP server. .. _`FTPHost.chmod`: - ``chmod(path, mode)`` sets the access mode (permission flags) for the given path. The mode is an integer as returned for the mode by the ``stat`` and ``lstat`` methods. Be careful: Usually, mode values are written as octal numbers, for example 0755 to make a directory readable and writable for the owner, but not writable for the group and others. If you want to use such octal values, rely on Python's support for them:: ftp_host.chmod("some_directory", 0o755) Not all FTP servers support the ``chmod`` command. In case of an exception, how do you know if the path doesn't exist or if the command itself is invalid? If the FTP server complies with `RFC 959`_, it should return a status code 502 if the ``SITE CHMOD`` command isn't allowed. ``ftputil`` maps this special error response to a ``CommandNotImplementedError`` which is derived from ``PermanentError``. So you need to code like this:: with ftputil.FTPHost(server, user, password) as ftp_host: try: ftp_host.chmod("some_file", 0o644) except ftputil.error.CommandNotImplementedError: # `chmod` not supported ... except ftputil.error.PermanentError: # Possibly a non-existent file ... Because the ``CommandNotImplementedError`` is more specific, you have to test for it first. .. _`RFC 959`: `RFC 959 - File Transfer Protocol (FTP)`_ - ``copyfileobj(source, target, length=64*1024)`` copies the contents from the file-like object ``source`` to the file-like object ``target``. The only difference to ``shutil.copyfileobj`` is the default buffer size. Note that arbitrary file-like objects can be used as arguments (e. g. local files, remote FTP files). However, the interfaces of ``source`` and ``target`` have to match; the string type read from ``source`` must be an accepted string type when written to ``target``. For example, if you open ``source`` in Python 3 as a local text file and ``target`` as a remote file object in binary mode, the transfer will fail since ``source.read`` gives unicode strings (``str``) whereas ``target.write`` only accepts byte strings (``bytes``). See `File-like objects`_ for the construction and use of remote file-like objects. .. _`set_parser`: - ``set_parser(parser)`` sets a custom parser for FTP directories. Note that you have to pass in a parser *instance*, not the class. An `extra section`_ shows how to write own parsers if the default parsers in ``ftputil`` don't work for you. .. _`extra section`: `Writing directory parsers`_ .. _`keep_alive`: - ``keep_alive()`` attempts to keep the connection to the remote server active in order to prevent timeouts from happening. This method is primarily intended to keep the underlying FTP connection of an ``FTPHost`` object alive while a file is uploaded or downloaded. This will require either an extra thread while the upload or download is in progress or calling ``keep_alive`` from a `callback function`_. The ``keep_alive`` method won't help if the connection has already timed out. In this case, a ``ftputil.error.TemporaryError`` is raised. If you want to use this method, keep in mind that FTP servers define a timeout for a reason. A timeout prevents running out of server connections because of clients that never disconnect on their own. Note that the ``keep_alive`` method does *not* affect the "hidden" FTP child connections established by ``FTPHost.open`` (see section `FTPHost instances vs. FTP connections`_ for details). You *can't* use ``keep_alive`` to avoid a timeout in a stalling transfer like this:: with ftputil.FTPHost(server, userid, password) as ftp_host: with ftp_host.open("some_remote_file", "rb") as fobj: data = fobj.read(100) # _Futile_ attempt to avoid file connection timeout. for i in range(15): time.sleep(60) ftp_host.keep_alive() # Will raise an `ftputil.error.TemporaryError`. data += fobj.read() .. _`FTPHost.open`: File-like objects ----------------- Construction ~~~~~~~~~~~~ Basics `````` ``FTPFile`` objects are returned by a call to ``FTPHost.open``; never use the ``FTPFile`` constructor directly. The APIs for remote file-like objects is modeled after the APIs of the built-in ``open`` function and its return value. - ``FTPHost.open(path, mode="r", buffering=None, encoding=None, errors=None, newline=None, rest=None)`` returns a file-like object that refers to the path on the remote host. This path may be absolute or relative to the current directory on the remote host (this directory can be determined with the ``getcwd`` method). As with local file objects, the default mode is "r", i. e. reading text files. Valid modes are "r", "rb", "w", and "wb". If a file is opened in binary mode, you *must not* specify an encoding. On the other hand, if you open a file in text mode, an encoding is used. By default, this is the return value of ``locale.getpreferredencoding``, but you can (and probably should) specify a distinct encoding. If you open a file in binary mode, the read and write operations use ``bytes`` objects. That is, read operations return ``bytes`` and write operations only accept ``bytes``. Similarly, text files always work with strings (``str``). Here, read operations return string and write operations only accept strings. The arguments ``buffering``, ``errors`` and ``newline`` have the same semantics as in open_. If the file is opened in binary mode, you may pass 0 or a positive integer for the ``rest`` argument. The argument is passed to the underlying FTP session instance (for example an instance of ``ftplib.FTP``) to start reading or writing at the given byte offset. For example, if a remote file contains the letters "abcdef" in ASCII encoding, ``rest=3`` will start reading at "d". .. warning:: If you pass ``rest`` values which point *after* the file, the behavior is undefined and may even differ from one FTP server to another. Therefore, use the ``rest`` argument only for error recovery in case of interrupted transfers. You need to keep track of the transferred data so that you can provide a valid ``rest`` argument for a resumed transfer. .. _`open`: https://docs.python.org/3/library/functions.html#open ``FTPHost.open`` can also be used in a ``with`` statement:: import ftputil with ftputil.FTPHost(...) as ftp_host: ... with ftp_host.open("new_file", "w", encoding="utf8") as fobj: fobj.write("This is some text.") At the end of the ``with`` block, the remote file will be closed automatically. If something goes wrong during the construction of the file or in the body of the ``with`` statement, the file will be closed as well. Exceptions will be propagated as with ``try ... finally``. Attributes and methods ~~~~~~~~~~~~~~~~~~~~~~ The methods :: close() read([count]) readline([count]) readlines() write(data) writelines(string_sequence) and the attribute ``closed`` have the same semantics as for file objects of a local disk file system. The iterator protocol is supported as well, i. e. you can use a loop to read a file line by line:: with ftputil.FTPHost(server, user, password) as ftp_host: with ftp_host.open("some_file") as input_file: for line in input_file: # Do something with the line, e. g. print(line.strip().replace("ftplib", "ftputil")) For more on file objects, see the section `File objects`_ in the Python Library Reference. .. _`file objects`: https://docs.python.org/3/glossary.html#term-file-object .. _`child_connections`: ``FTPHost`` instances vs. FTP connections ----------------------------------------- This section explains why keeping an ``FTPHost`` instance "alive" without timing out sometimes isn't trivial. If you always finish your FTP operations in time, you don't need to read this section. The file transfer protocol is a stateful protocol. That means an FTP connection always is in a certain state. Each of these states can only change to certain other states under certain conditions triggered by the client or the server. One of the consequences is that a single FTP connection can't be used at the same time, say, to transfer data on the FTP data channel and to create a directory on the remote host. For example, consider this:: >>> import ftplib >>> ftp = ftplib.FTP(server, user, password) >>> ftp.pwd() '/' >>> # Start transfer. `CONTENTS` is a text file on the server. >>> socket = ftp.transfercmd("RETR CONTENTS") >>> socket >>> ftp.pwd() Traceback (most recent call last): File "", line 1, in File "/usr/lib64/python2.7/ftplib.py", line 578, in pwd return parse257(resp) File "/usr/lib64/python2.7/ftplib.py", line 842, in parse257 raise error_reply, resp ftplib.error_reply: 226-File successfully transferred 226 0.000 seconds (measured here), 5.60 Mbytes per second >>> Note that ``ftp`` is a single FTP connection, represented by an ``ftplib.FTP`` instance, not an ``ftputil.FTPHost`` instance. On the other hand, consider this:: >>> import ftputil >>> ftp_host = ftputil.FTPHost(server, user, password) >>> ftp_host.getcwd() >>> fobj = ftp_host.open("CONTENTS") >>> fobj >>> ftp_host.getcwd() u'/' >>> fobj.readline() u'Contents of FTP test directory\n' >>> fobj.close() >>> To be able to start a file transfer (i. e. open a remote file for reading or writing) and still be able to use other FTP commands, ftputil uses a trick. For every remote file, ftputil creates a new FTP connection, called a child connection in the ftputil source code. (Actually, FTP connections belonging to closed remote files are re-used if they haven't timed out yet.) In most cases this approach isn't noticeable by code using ftputil. However, the nice abstraction of dealing with a single FTP connection falls apart if one of the child connections times out. For example, if you open a remote file and work only with the initial "main" connection to navigate the file system, the FTP connection for the remote file may eventually time out. While it's often relatively easy to prevent the "main" connection from timing out it's unfortunately practically impossible to do this for a remote file connection (apart from transferring some data, of course). For this reason, `FTPHost.keep_alive`_ affects only the main connection. Child connections may still time out if they're idle for too long. .. _`FTPHost.keep_alive`: `keep_alive`_ Some more details: - A kind of "straightforward" way of keeping the main connection alive would be to call ``ftp_host.getcwd()``. However, this doesn't work because ftputil caches the current directory and returns it without actually contacting the server. That's the main reason why there's a ``keep_alive`` method since it calls ``pwd`` on the FTP connection (i. e. the session object), which isn't a public attribute. - Some servers define not only an idle timeout but also a transfer timeout. This means the connection times out unless there's some transfer on the data channel for this connection. So ftputil's ``keep_alive`` doesn't prevent this timeout, but an ``ftp_host.listdir(ftp_host.curdir)`` call should do it. However, this transfers the data for the whole directory listing which might take some time if the directory has many entries. Bottom line: If you can, you should organize your FTP actions so that you finish everything before a timeout happens. Writing directory parsers ------------------------- ``ftputil`` recognizes the two most widely-used FTP directory formats, Unix and MS style, and adjusts itself automatically. Almost every FTP server uses one of these formats. However, if your server uses a format which is different from the two provided by ``ftputil``, you can plug in a custom parser with a single method call and have ``ftputil`` use this parser. For this, you need to write a parser class by inheriting from the class ``Parser`` in the ``ftputil.stat`` module. Here's an example:: import ftputil.error import ftputil.stat class XyzParser(ftputil.stat.Parser): """ Parse the default format of the FTP server of the XYZ corporation. """ def parse_line(self, line, time_shift=0.0): """ Parse a `line` from the directory listing and return a corresponding `StatResult` object. If the line can't be parsed, raise `ftputil.error.ParserError`. The `time_shift` argument can be used to fine-tune the parsing of dates and times. See the class `ftputil.stat.UnixParser` for an example. """ # Split the `line` argument and examine it further; if # something goes wrong, raise an `ftputil.error.ParserError`. ... # Make a `StatResult` object from the parts above. stat_result = ftputil.stat.StatResult(...) # `_st_name`, `_st_target` and `_st_mtime_precision` are optional. stat_result._st_name = ... stat_result._st_target = ... stat_result._st_mtime_precision = ... return stat_result # Define `ignores_line` only if the default in the base class # doesn't do enough! def ignores_line(self, line): """ Return a true value if the line should be ignored. For example, the implementation in the base class handles lines like "total 17". On the other hand, if the line should be used for stat'ing, return a false value. """ is_total_line = super().ignores_line(line) my_test = ... return is_total_line or my_test A ``StatResult`` object is similar to the value returned by `os.stat`_ and is usually built with statements like :: stat_result = StatResult( (st_mode, st_ino, st_dev, st_nlink, st_uid, st_gid, st_size, st_atime, st_mtime, st_ctime)) stat_result._st_name = ... stat_result._st_target = ... stat_result._st_mtime_precision = ... with the arguments of the ``StatResult`` constructor described in the following table. ===== =================== ============ =================== ======================= Index Attribute os.stat type ``StatResult`` type Notes ===== =================== ============ =================== ======================= 0 st_mode int int 1 st_ino long long 2 st_dev long long 3 st_nlink int int 4 st_uid int str usually only available as string 5 st_gid int str usually only available as string 6 st_size long long 7 st_atime int/float float 8 st_mtime int/float float 9 st_ctime int/float float \- _st_name \- str file name without directory part \- _st_target \- str link target (may be absolute or relative) \- _st_mtime_precision \- int ``st_mtime`` precision in seconds ===== =================== ============ =================== ======================= If you can't extract all the desirable data from a line (for example, the MS format doesn't contain any information about the owner of a file), set the corresponding values in the ``StatResult`` instance to ``None``. Parser classes can use several helper methods which are defined in the class ``Parser``: - ``parse_unix_mode`` parses strings like "drwxr-xr-x" and returns an appropriate ``st_mode`` integer value. - ``parse_unix_time`` returns a float number usable for the ``st_...time`` values by parsing arguments like "Nov"/"23"/"02:33" or "May"/"26"/"2005". Note that the method expects the timestamp string already split at whitespace. - ``parse_ms_time`` parses arguments like "10-23-01"/"03:25PM" and returns a float number like from ``time.mktime``. Note that the method expects the timestamp string already split at whitespace. Additionally, there's an attribute ``_month_numbers`` which maps lowercase three-letter month abbreviations to integers. For more details, see the two "standard" parsers ``UnixParser`` and ``MSParser`` in the module ``ftputil/stat.py``. To actually *use* the parser, call the method `set_parser`_ of the ``FTPHost`` instance. If you can't write a parser or don't want to, please ask on the `ftputil mailing list`_. Possibly someone has already written a parser for your server or can help with it. FAQ / Tips and tricks --------------------- Where can I get the latest version? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ See the `download page`_. Announcements will be sent to the `mailing list`_. Announcements on major updates will also be posted to the `Python announcements list`_. .. _`download page`: https://ftputil.sschwarzer.net/download .. _`mailing list`: https://ftputil.sschwarzer.net/mailinglist .. _`Python announcements list`: https://mail.python.org/mailman3/lists/python-announce-list.python.org/ Is there a mailing list on ``ftputil``? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Yes, please visit https://ftputil.sschwarzer.net/mailinglist to subscribe or read the archives. Though you can *technically* post without subscribing first I can't recommend it: The mails from non-subscribers have to be approved by me and because the arriving mails contain *lots* of spam, I rarely go through these mails. I found a bug! What now? ~~~~~~~~~~~~~~~~~~~~~~~~ Before reporting a bug, make sure that you already read this manual and tried the `latest version`_ of ``ftputil``. There the bug might have already been fixed. .. _`latest version`: https://ftputil.sschwarzer.net/download Please see https://ftputil.sschwarzer.net/issuetrackernotes for guidelines on entering a bug in ``ftputil``'s ticket system. If you are unsure if the behaviour you found is a bug or not, you should write to the `ftputil mailing list`_. *Never* include confidential information (user id, password, file names, etc.) in the problem report! Be careful! Does ``ftputil`` support TLS? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ``ftputil`` has no *built-in* TLS support. On the other hand, there are two ways to get TLS support with ftputil: - The ``ftplib`` library has a class ``FTP_TLS`` that you can use for the ``session_factory`` keyword argument in the ``FTPHost`` constructor. You can't use the class directly though *if* you need additional setup code in comparison to ``ftplib.FTP``, for example calling ``prot_p``, to secure the data connection. On the other hand, `ftputil.session.session_factory`_ can be used to create a custom session factory. - If you have other requirements that ``session_factory`` can't fulfill, you may create your own session factory by inheriting from ``ftplib.FTP_TLS``:: import ftplib import ftputil class FTPTLSSession(ftplib.FTP_TLS): def __init__(self, host, user, password): ftplib.FTP_TLS.__init__(self) self.connect(host, port) self.login(user, password) # Set up encrypted data connection. self.prot_p() ... # Note the `session_factory` parameter. Pass the class, not # an instance. with ftputil.FTPHost(server, user, password, session_factory=FTPTLSSession) as ftp_host: # Use `ftp_host` as usual. ... .. _`ftputil.session.session_factory`: `Session factories`_ How do I connect to a non-default port? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ By default, an instantiated ``FTPHost`` object connects on the usual FTP port. If you have to use a different port, refer to the section `Session factories`_. How do I set active or passive mode? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Please see the section `Session factories`_. How can I debug an FTP connection problem? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can do this with a session factory. See `Session factories`_. If you want to change the debug level only temporarily after the connection is established, you can reach the `session object`_ as the ``_session`` attribute of the ``FTPHost`` instance and call ``_session.set_debuglevel``. Note that the ``_session`` attribute should *only* be accessed for debugging. Calling arbitrary ``ftplib.FTP`` methods on the session object may *cause* bugs! .. _`session object`: `Session factories`_ Conditional upload/download to/from a server in a different time zone ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You may find that ``ftputil`` uploads or downloads files unnecessarily, or not when it should. Please see the section on `time zone correction`_. It may even be sufficient to call `synchronize_times`_. When I use ``ftputil``, all I get is a ``ParserError`` exception ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The FTP server you connect to may use a directory format that ``ftputil`` doesn't understand. You can either write and `plug in your own parser`_ or ask on the `mailing list`_ for help. .. _`plug in your own parser`: `Writing directory parsers`_ ``isdir``, ``isfile`` or ``islink`` incorrectly return ``False`` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Like Python's counterparts under `os.path`_, ``ftputil``'s methods return ``False`` if they can't find the given path. Probably you used ``listdir`` on a directory and called ``is...()`` on the returned names. But if the argument for ``listdir`` wasn't the current directory, the paths won't be found and so all ``is...()`` variants will return ``False``. I don't find an answer to my problem in this document ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Please send an email with your problem report or question to the `ftputil mailing list`_, and we'll see what we can do for you. :-) Bugs and limitations -------------------- - ``ftputil`` needs at least Python 3.6 to work. - Whether ``ftputil`` "sees" "hidden" directory and file names (i. e. names starting with a dot) depends on the configuration of the FTP server. See `Hidden files and directories`_ for details. - Due to the implementation of ``lstat`` it can not return a sensible value for the root directory ``/`` though stat'ing entries *in* the root directory isn't a problem. If you know an implementation that can do this, please let me know. The root directory is handled appropriately in ``FTPHost.path.exists/isfile/isdir/islink``, though. - In multithreaded programs, you can have each thread use one or more ``FTPHost`` instances as long as no instance is shared with other threads. - Currently, it is not possible to continue an interrupted upload or download. Contact me if this causes problems for you. - There's exactly one cache for ``lstat`` results for each ``FTPHost`` object, i. e. there's no sharing of cache results determined by several ``FTPHost`` objects. See `Local caching of file system information`_ for the reasons. Files ----- If not overwritten via installation options, the ``ftputil`` files reside in the ``ftputil`` package. There's also documentation in `reStructuredText`_ and in HTML format. The locations of these files after installation is system-dependent. .. _`reStructuredText`: https://docutils.sourceforge.net/rst.html The files ``test_*.py`` and ``scripted_session.py`` are for unit-testing. If you only *use* ``ftputil``, i. e. *don't* modify it, you can delete these files. References ---------- - Postel J, Reynolds J. 1985. `RFC 959 - File Transfer Protocol (FTP)`_. - Python Software Foundation. 2020. `The Python Standard Library`_. .. _`RFC 959 - File Transfer Protocol (FTP)`: https://www.ietf.org/rfc/rfc959.txt .. _`The Python Standard Library`: https://docs.python.org/library/index.html Authors ------- ``ftputil`` is written by Stefan Schwarzer and contributors (see ``doc/contributors.txt``). The original ``lrucache`` module was written by Evan Prodromou . Feedback is appreciated. :-)