add examples for dynamic linking / loading

one example by doing it manually with an ugly Makefile,
another one by using autotools.

Signed-off-by: Manuel Traut <manut@linutronix.de>

1 files changed, 20 insertions, 0 deletions

diff --git a/schulung_tools/linking/hello/shared_library.txt b/schulung_tools/linking/hello/shared_library.txt
new file mode 100644
index 0000000..1dd0f9f
--- /dev/null
+++ b/schulung_tools/linking/hello/shared_library.txt
@@ -0,0 +1,20 @@
+# build shared library
+gcc -fPIC -shared -Wl,-soname,libhello.so.1 -olibhello.so.1.0.3 libhello.c
+
+# install shared library
+sudo mkdir -p /opt/myfirma/lib
+sudo cp libhello.so.1.0.3 /opt/myfirma/lib
+
+# add custom path to dynamic loader search path
+echo "/opt/myfirma/lib" | sudo tee /etc/ld.so.conf.d/myfirma.conf
+
+# refresh dynamic loader cache
+sudo ldconfig
+
+# verify custom library is in cache
+/sbin/ldconfig -p | grep libhello.so.1
+
+# compile program using custom library
+ln -s /opt/myfirma/lib/libhello.so.1.0.3 libhello.so
+gcc -L. -ohello hello.c -lhello
+rm libhello.so