Package duplicity :: Module backend :: Class Backend

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Class Backend

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Represents a generic duplicity backend, capable of storing and retrieving files.

Concrete sub-classes are expected to implement:

put
get
list
delete
close (if needed)

Instance Methods

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__init__(self, parsed_url)

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put(self, source_path, remote_filename=None)
Transfer source_path (Path object) to remote_filename (string)

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get(self, remote_filename, local_path)
Retrieve remote_filename and place in local_path

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list(self)
Return list of filenames (strings) present in backend

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delete(self, filename_list)
Delete each filename in filename_list, in order if possible.

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get_password(self)
Return a password for authentication purposes.

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munge_password(self, commandline)
Remove password from commandline by substituting the password found in the URL, if any, with a generic place-holder.

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run_command(self, commandline)
Execute the given command line, interpreted as a shell command, with logging and error detection.

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run_command_persist(self, commandline)
Like run_command(), but repeat the attempt several times (with a delay in between) if it fails.

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popen(self, commandline)
Like run_command(), but capture stdout and return it (the contents read from stdout) as a string.

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popen_persist(self, commandline)
Like run_command_persist(), but capture stdout and return it (the contents read from stdout) as a string.

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get_fileobj_read(self, filename, parseresults=None)
Return fileobject opened for reading of filename on backend

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get_fileobj_write(self, filename, parseresults=None, sizelist=None)
Return fileobj opened for writing, which will cause the file to be written to the backend on close().

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get_data(self, filename, parseresults=None)
Retrieve a file from backend, process it, return contents.

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put_data(self, buffer, filename, parseresults=None)
Put buffer into filename on backend after processing.

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close(self)
Close the backend, releasing any resources held and invalidating any file objects obtained from the backend.

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Method Details

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put(self, source_path, remote_filename=None)

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Transfer source_path (Path object) to remote_filename (string)

If remote_filename is None, get the filename from the last path component of pathname.

get_password(self)

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Return a password for authentication purposes. The password will be obtained from the backend URL, the environment, by asking the user, or by some other method. When applicable, the result will be cached for future invocations.

munge_password(self, commandline)

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Remove password from commandline by substituting the password found in the URL, if any, with a generic place-holder.

This is intended for display purposes only, and it is not guaranteed that the results are correct (i.e., more than just the password may be substituted if the password is also a substring of another part of the command line).

run_command(self, commandline)

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Execute the given command line, interpreted as a shell command, with logging and error detection. If execution fails, raise a BackendException.

get_fileobj_read(self, filename, parseresults=None)

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Return fileobject opened for reading of filename on backend

The file will be downloaded first into a temp file. When the returned fileobj is closed, the temp file will be deleted.

get_fileobj_write(self, filename, parseresults=None, sizelist=None)

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Return fileobj opened for writing, which will cause the file to be written to the backend on close().

The file will be encoded as specified in parseresults (or as read from the filename), and stored in a temp file until it can be copied over and deleted.

If sizelist is not None, it should be set to an empty list. The number of bytes will be inserted into the list.