Usage: xz [OPTION]... [FILE]...
Compress or decompress FILEs in the .xz format.
Mandatory arguments to long options are mandatory for short options too.
-z, --compress force compression
-d, --decompress force decompression
-t, --test test compressed file integrity
-l, --list list information about .xz files
-k, --keep keep (don't delete) input files
-f, --force force overwrite of output file and (de)compress links
-c, --stdout write to standard output and don't delete input files
-0 ... -9 compression preset; default is 6; take compressor *and*
decompressor memory usage into account before using 7-9!
-e, --extreme try to improve compression ratio by using more CPU time;
does not affect decompressor memory requirements
e9? is this a e926 reference?
Not really.