如何使用 XZ 文件设置 tarfile 的压缩级别？

Question

In Python an xz tarfile can be created:

handle = tarfile.open(dest, 'w:xz')

However this doesn't set the compression level.

Is it possible to set the XZ compression level with tarfile?

Answer 1

The answer is a bit buried in the tarfile.open() documentation, but it says:

For modes 'w:gz', 'r:gz', 'w:bz2', 'r:bz2', 'x:gz', 'x:bz2', tarfile.open() accepts the keyword argument compresslevel (default 9) to specify the compression level of the file.

Unfortunately, the documentation doesn't mention 'w:xz' as being supported. Trying it out just in case, I can confirm that it does not. This appears to be because the lzma module doesn't support a compresslevel argument. It does, however, support preset . Why they choose a different name here? Who knows. :-( It does appear they made a different choice for the default compression level. With the others, they chose the maximum level by default. With xz, they chose for the default level of compression used by the tool (level 6).

Which means you'd do something like this:

handle = tarfile.open(dest, 'w:xz', preset=9)