[Buildroot] [PATCH v7 18/18] docs/manual: document how to debug shell script

[Samuel Martin]

The method describes here is only true for scripts using the shell
modules from support/scripts/shell/*.

Signed-off-by: Samuel Martin <s.martin49 at gmail.com>

---
changes v6->v7:
- new patch
---
 docs/manual/debugging-buildroot.txt | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/docs/manual/debugging-buildroot.txt b/docs/manual/debugging-buildroot.txt
index f575fc4..c497284 100644
--- a/docs/manual/debugging-buildroot.txt
+++ b/docs/manual/debugging-buildroot.txt
@@ -41,3 +41,18 @@ The script has access to the following variables:
   - +BINARIES_DIR+: the place where all binary files (aka images) are
     stored
   - +BASE_DIR+: the base output directory
+
+=== Debugging shell scripts in Buildroot
+
+For shell scripts using the _shell modules_ (available in
++support/scripts/shell/+), there is a couple of environment variables
+you can set to trace the scripts
+
+  - +SHELL_DEBUG+ adjustes the debug level, from 0 to 3 (only errors to
+    all debug messages)
+
+To enable these debug outputs:
+
+----
+SHELL_DEBUG=3 make
+----
-- 
2.7.2