bitbake: user-manual-metadata.xml: Sections to handle variable setting added.

Fixes [YOCTO #5507]

I provided further explanation in the "Basic Variable Setting"
section to note that trailing and leading blanks are not stripped
from a value when set (e.g. VARIABLE = " value").

I added a new section "Null and Blank Setting" explaning that setting
a variable to "" and " " are two different things.

(Bitbake rev: 96d0b38577476a3576487f1fa9a4b6c9dff5d3ed)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/bitbake/doc/user-manual/user-manual-metadata.xml b/bitbake/doc/user-manual/user-manual-metadata.xml
index f7682c0fed..9cd1a9d922 100644
--- a/bitbake/doc/user-manual/user-manual-metadata.xml
+++ b/bitbake/doc/user-manual/user-manual-metadata.xml
@@ -30,6 +30,26 @@
                 <literallayout class='monospaced'>
      VARIABLE = "value"
                 </literallayout>
+                As expected, if you include leading or trailing spaces as part of
+                an assignment, the spaces are retained:
+                <literallayout class='monospaced'>
+     VARIABLE = " value"
+     VARIABLE = "value "
+                </literallayout>
+            </para>
+        </section>
+
+        <section id='null-and-blank-variable-setting'>
+            <title>Null and Blank Variable Setting</title>
+
+            <para>
+                Setting <filename>VARIABLE</filename> to "" sets it to null,
+                while setting the variable to " " sets it to a blank space
+                (i.e. these are not the same values).
+                <literallayout class='monospaced'>
+     VARIABLE = ""
+     VARIABLE = " "
+                </literallayout>
             </para>
         </section>