From: Richard Jones <rjones@redhat.com>
Date: Thu, 27 May 2010 09:25:18 +0000 (+0100)
Subject: Clarify sparse behaviour of truncate-size command.
X-Git-Tag: 1.3.17~4
X-Git-Url: http://git.annexia.org/?p=libguestfs.git;a=commitdiff_plain;h=d12a702fe1898f3ea421210d92c705440efe07a8;hp=4412fd951ee7766ee9a70bf66b5cf11378a64ed0

Clarify sparse behaviour of truncate-size command.
---

diff --git a/src/generator.ml b/src/generator.ml
index 2209e68..99d80fb 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -3925,8 +3925,13 @@ file must exist already.");
    "truncate a file to a particular size",
    "\
 This command truncates C<path> to size C<size> bytes.  The file
-must exist already.  If the file is smaller than C<size> then
-the file is extended to the required size with null bytes.");
+must exist already.
+
+If the current file size is less than C<size> then
+the file is extended to the required size with zero bytes.
+This creates a sparse file (ie. disk blocks are not allocated
+for the file until you write to it).  To create a non-sparse
+file of zeroes, use C<guestfs_fallocate64> instead.");
 
   ("utimens", (RErr, [Pathname "path"; Int64 "atsecs"; Int64 "atnsecs"; Int64 "mtsecs"; Int64 "mtnsecs"]), 201, [],
    [InitBasicFS, Always, TestOutputStruct (