.\" This file has been put into the public domain.
.\" You can do whatever you want with this file.
.\"
-.TH XZ 1 "2010-09-27" "Tukaani" "XZ Utils"
+.TH XZ 1 "2010-10-04" "Tukaani" "XZ Utils"
.
.SH NAME
xz, unxz, xzcat, lzma, unlzma, lzcat \- Compress or decompress .xz and .lzma files
.I File
is not a regular file.
Symbolic links are not followed,
-thus they are not considered to be regular files.
+and thus they are not considered to be regular files.
.IP \(bu 3
.I File
has more than one hard link.
.I File
has setuid, setgid, or sticky bit set.
.IP \(bu 3
-The operation mode is set to compress, and the
+The operation mode is set to compress and the
.I file
already has a suffix of the target file format
.RB ( .xz
.B .lzma
format).
.IP \(bu 3
-The operation mode is set to decompress, and the
+The operation mode is set to decompress and the
.I file
doesn't have a suffix of any of the supported file formats
.RB ( .xz ,
\fB\-\-memlimit\-decompress=\fIlimit\fR.
Using these two options outside
.B XZ_DEFAULTS
-is rarely useful, because a single run of
+is rarely useful because a single run of
.B xz
cannot do both compression and decompression and
.BI \-\-memlimit= limit
.BR \-z ", " \-\-compress
Compress.
This is the default operation mode when no operation mode option
-is specified, and no other operation mode is implied from
+is specified and no other operation mode is implied from
the command name (for example,
.B unxz
implies
option.
For even more information, use
.B \-\-verbose
-twice, but note that it may be slow, because getting all the extra
+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 e.g.\&
.B xz
tries to make the file sparse if the decompressed data contains
long sequences of binary zeros.
-It works also when writing to standard output
-as long as standard output is connected to a regular file,
+It also works when writing to standard output
+as long as standard output is connected to a regular file
and certain additional conditions are met to make it safe.
Creating sparse files may save disk space and speed up
the decompression by reducing the amount of disk I/O.
.RE
.TP
\fB\-C\fR \fIcheck\fR, \fB\-\-check=\fIcheck
-Specify the type of the integrity check, which is calculated
-from the uncompressed data.
+Specify the type of the integrity check.
+The check is calculated from the uncompressed data and
+stored in the
+.B .xz
+file.
This option has an effect only when compressing into the
.B .xz
format; the
will adjust the settings downwards so that
the limit is no longer exceeded and display a notice that
automatic adjustment was done.
-Adjustment is never done when compressing with
+Such adjustments are not made when compressing with
.B \-\-format=raw
or if
.B \-\-no\-adjust
.I limit
to
.B max
-i.e. no memory usage limit.
+(no memory usage limit).
Once multithreading support has been implemented,
there may be a difference between
.B 0
.TP
.BI \-\-memlimit\-decompress= limit
Set a memory usage limit for decompression.
-This affects also the
+This also affects the
.B \-\-list
mode.
If the operation is not possible without exceeding the
The maximum number of filters in the chain is four,
but typically a filter chain has only one or two filters.
.PP
-Many filters have limitations where they can be
+Many filters have limitations on where they can be
in the filter chain:
some filters can work only as the last filter in the chain,
some only as a non-last filter, and some work in any position
.RE
.TP
\fB\-\-delta\fR[\fB=\fIoptions\fR]
-Add Delta filter to the filter chain.
-The Delta filter can be used only as non-last filter
+Add the Delta filter to the filter chain.
+The Delta filter can be only used as a non-last filter
in the filter chain.
.IP ""
Currently only simple byte-wise delta calculation is supported.
.IP \(bu 3
Completion percentage is shown
if the size of the input file is known.
-That is, percentage cannot be shown in pipes.
+That is, the percentage cannot be shown in pipes.
.IP \(bu 3
Amount of compressed data produced (compressing)
or consumed (decompressing).
header.
LZMA Utils does that when compressing regular files.
The alternative is to mark that uncompressed size is unknown
-and use end of payload marker to indicate
+and use end-of-payload marker to indicate
where the decompressor should stop.
LZMA Utils uses this method when uncompressed size isn't known,
which is the case for example in pipes.
.B xz
supports decompressing
.B .lzma
-files with or without end of payload marker, but all
+files with or without end-of-payload marker, but all
.B .lzma
files created by
.B xz
-will use end of payload marker and have uncompressed size
+will use end-of-payload marker and have uncompressed size
marked as unknown in the
.B .lzma
header.