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36.

The memory usage limiter can be enabled with the command line option B<--memlimit=>I<limit>. Often it is more convenient to enable the limiter by default by setting the environment variable B<XZ_DEFAULTS>, for example, B<XZ_DEFAULTS=--memlimit=150MiB>. It is possible to set the limits separately for compression and decompression by using B<--memlimit-compress=>I<limit> and B<--memlimit-decompress=>I<limit>. Using these two options outside B<XZ_DEFAULTS> is rarely useful because a single run of B<xz> cannot do both compression and decompression and B<--memlimit=>I<limit> (or B<-M> I<limit>) is shorter to type on the command line.

37.

If the specified memory usage limit is exceeded when decompressing, B<xz> will display an error and decompressing the file will fail. If the limit is exceeded when compressing, B<xz> will try to scale the settings down so that the limit is no longer exceeded (except when using B<--format=raw> or B<--no-adjust>). This way the operation won't fail unless the limit is very small. The scaling of the settings is done in steps that don't match the compression level presets, for example, if the limit is only slightly less than the amount required for B<xz -9>, the settings will be scaled down only a little, not all the way down to B<xz -8>.

40.

It is possible to insert padding between the concatenated parts or after the last part. The padding must consist of null bytes and the size of the padding must be a multiple of four bytes. This can be useful, for example, if the B<.xz> file is stored on a medium that measures file sizes in 512-byte blocks.

62.

The default listing shows basic information about I<files>, one file per line. To get more detailed information, use also the B<--verbose> option. For even more information, use B<--verbose> twice, but note that this may be slow, because getting all the extra information requires many seeks. The width of verbose output exceeds 80 characters, so piping the output to, for example, B<less\ -S> may be convenient if the terminal isn't wide enough.

67.

Since B<xz> 5.2.6, this option also makes B<xz> compress or decompress even if the input is a symbolic link to a regular file, has more than one hard link, or has the setuid, setgid, or sticky bit set. The setuid, setgid, and sticky bits are not copied to the target file. In earlier versions this was only done with B<--force>.

83.

When decompressing, recognize files with the suffix I<.suf> in addition to files with the B<.xz>, B<.txz>, B<.lzma>, B<.tlz>, or B<.lz> suffix. If the source file has the suffix I<.suf>, the suffix is removed to get the target filename.

100.

The B<.lz> format version 0 and the unextended version 1 are supported. Version 0 files were produced by B<lzip> 1.3 and older. Such files aren't common but may be found from file archives as a few source packages were released in this format. People might have old personal files in this format too. Decompression support for the format version 0 was removed in B<lzip> 1.18.

127.

Good to very good compression while keeping decompressor memory usage reasonable even for old systems. B<-6> is the default, which is usually a good choice for distributing files that need to be decompressible even on systems with only 16\ MiB RAM. (B<-5e> or B<-6e> may be worth considering too. See B<--extreme>.)

201.

In multi-threaded mode about three times I<size> bytes will be allocated in each thread for buffering input and output. The default I<size> is three times the LZMA2 dictionary size or 1 MiB, whichever is more. Typically a good value is 2\(en4 times the size of the LZMA2 dictionary or at least 1 MiB. Using I<size> less than the LZMA2 dictionary size is waste of RAM because then the LZMA2 dictionary buffer will never get fully used. The sizes of the blocks are stored in the block headers, which a future version of B<xz> will use for multi-threaded decompression.

216.

If the compression settings exceed the I<limit>, B<xz> will attempt to adjust the settings downwards so that the limit is no longer exceeded and display a notice that automatic adjustment was done. The adjustments are done in this order: reducing the number of threads, switching to single-threaded mode if even one thread in multi-threaded mode exceeds the I<limit>, and finally reducing the LZMA2 dictionary size.