exercise2 and exercise3, add functions folder

exit_return_codes/exercise2.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+FD_NAME=$1
+
+if [ -f $FD_NAME ]
+then
+    echo "${FD_NAME} is a regular file."
+    exit 0
+elif [ -d $FD_NAME ]
+then
+    echo "${FD_NAME} is a regular directory."
+    exit 1
+else
+    echo "${FD_NAME} is NOT a regular file or directory."
+    exit 2
+fi
+
+# Exit with an explicit exit status.
+exit 0

exit_return_codes/exercise3.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+#
+# <Replace with the purpose or description of of this shell script.>
+#
+
+cat /etc/shadow
+
+if [ "$?" -ne "0" ]
+then
+    echo "Command failed"
+    exit 1
+else
+    echo "Command succeeded"
+    exit 0
+fi
+
+# Exit with an explicit exit status.
+exit 0