Create sparse files by default when decompressing into

a regular file.

Sparse file creation can be disabled with --no-sparse.
I don't promise yet that the name of this option won't
change before 5.0.0. It's possible that the code, that
checks when it is safe to use sparse output on stdout,
is not good enough, and a more flexible command line
option is needed to configure sparse file handling.

1 files changed, 11 insertions, 0 deletions

diff --git a/src/xz/xz.1 b/src/xz/xz.1
index b8115624..94aa562e 100644
--- a/src/xz/xz.1
+++ b/src/xz/xz.1
@@ -336,6 +336,17 @@ Write the compressed or decompressed data to standard output instead of
 a file. This implies
 .BR \-\-keep .
 .TP
+.B \-\-no\-sparse
+Disable creation of sparse files. By default, if decompressing into
+a regular file,
+.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, 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.
+.TP
 \fB\-S\fR \fI.suf\fR, \fB\-\-suffix=\fI.suf
 When compressing, use
 .I .suf