diff --git a/README.md b/README.md
index 58ad63d..bb628d8 100644
--- a/README.md
+++ b/README.md
@@ -51,7 +51,7 @@ Although *3* introduces a node.js dependency, this does allow for easy version p
 
 ### master (Unreleased)
 
-- tba
+- Add tests for `ini_val` and follow Library export best practices
 
 ### v1.2.1 (2016-02-17)
 
diff --git a/src/ini_val.sh b/src/ini_val.sh
index 0f7b2ed..a07b022 100755
--- a/src/ini_val.sh
+++ b/src/ini_val.sh
@@ -1,8 +1,39 @@
 #!/usr/bin/env bash
+# BASH3 Boilerplate: ini_val
+#
+# This file:
+#  - Can read and write .ini files using pure bash
+#
+# Limitations:
+#  - All keys inside the .ini file must be unique, regardless of the use of sections
+#
+# More info:
+#  - https://github.com/kvz/bash3boilerplate
+#  - http://kvz.io/blog/2013/02/26/introducing-bash3boilerplate/
+#
+# Version: 1.2.1
+#
+# Authors:
+#  - Kevin van Zonneveld (http://kvz.io)
+#  - Izaak Beekman (https://izaakbeekman.com/)
+#  - Alexander Rathai (Alexander.Rathai@gmail.com)
+#
+# Usage as a function:
+#
+#  source ini_val.sh
+#  ini_val data.ini connection.host 127.0.0.1
+#
+# Usage as a command:
+#
+#  ini_val.sh data.ini connection.host 127.0.0.1
+#
+# Licensed under MIT
+# Copyright (c) 2016 Kevin van Zonneveld (http://kvz.io)
+
 function ini_val() {
-  local file="${1}"
-  local sectionkey="${2}"
-  local val="${3}"
+  local file="${1:-}"
+  local sectionkey="${2:-}"
+  local val="${3:-}"
   local delim=" = "
   local section=""
   local key=""
@@ -14,7 +45,7 @@ function ini_val() {
     section=""
   fi
 
-  local current=$(awk -F"${delim}" "/^${key}${delim}/ {for (i=2; i<NF; i++) printf \$i \" \"; print \$NF}" "${file}")
+  local current=$(awk -F "${delim}" "/^${key}${delim}/ {for (i=2; i<NF; i++) printf \$i \" \"; print \$NF}" "${file}")
   if [ -z "${val}" ]; then
     # get a value
     echo "${current}"
@@ -28,11 +59,22 @@ function ini_val() {
         echo "${key}${delim}${val}" >> "${file}"
       else
         # add to section
-        sed "/\[${section}\]/a ${key}${delim}${val}" -i "${file}"
+        sed -i.bak -e "/\[${section}\]/a ${key}${delim}${val}" "${file}"
+        # this .bak dance is done for BSD/GNU portability: http://stackoverflow.com/a/22084103/151666
+        rm -f "${file}.bak"
       fi
     else
       # replace existing
-      sed "/^${key}${delim}/s/${delim}.*/${delim}${val}/" -i "${file}"
+      sed -i.bak -e "/^${key}${delim}/s/${delim}.*/${delim}${val}/" "${file}"
+      # this .bak dance is done for BSD/GNU portability: http://stackoverflow.com/a/22084103/151666
+      rm -f "${file}.bak"
     fi
   fi
 }
+
+if [ "${BASH_SOURCE[0]}" != ${0} ]; then
+  export -f ini_val
+else
+  ini_val "${@}"
+  exit ${?}
+fi
diff --git a/test/fixture/inival.exitcode b/test/fixture/inival.exitcode
new file mode 100644
index 0000000..573541a
--- /dev/null
+++ b/test/fixture/inival.exitcode
@@ -0,0 +1 @@
+0
diff --git a/test/fixture/inival.stdio b/test/fixture/inival.stdio
new file mode 100644
index 0000000..5034a09
--- /dev/null
+++ b/test/fixture/inival.stdio
@@ -0,0 +1,24 @@
+--> command: Read 3 values
+exists
+127.0.0.1
+nginx, nodejs
+--> command: Replace three values in-place and show result
+orphan = no more
+
+[connection]
+host = 192.168.0.1
+
+[software]
+packages = vim
+--> function: Read 3 values
+exists
+127.0.0.1
+nginx, nodejs
+--> function: Replace three values in-place and show result
+orphan = no more
+
+[connection]
+host = 192.168.0.1
+
+[software]
+packages = vim
diff --git a/test/scenario/inival/data.ini b/test/scenario/inival/data.ini
new file mode 100644
index 0000000..d55cef4
--- /dev/null
+++ b/test/scenario/inival/data.ini
@@ -0,0 +1,7 @@
+orphan = exists
+
+[connection]
+host = 127.0.0.1
+
+[software]
+packages = nginx, nodejs
diff --git a/test/scenario/inival/run.sh b/test/scenario/inival/run.sh
new file mode 100644
index 0000000..bb2e112
--- /dev/null
+++ b/test/scenario/inival/run.sh
@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+set -o pipefail
+set -o errexit
+set -o nounset
+# set -o xtrace
+
+# Set magic variables for current FILE & DIR
+__dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+__file="${__dir}/$(basename "${BASH_SOURCE[0]}")"
+__base="$(basename ${__file} .sh)"
+__root="$(cd "$(dirname $(dirname $(dirname "${__dir}")))" && pwd)"
+
+# echo "B3BP:STDIO_REPLACE_DATETIMES"
+
+
+# Use as standalone:
+cp -f data.ini dummy.ini
+echo "--> command: Read 3 values"
+bash "${__root}/src/ini_val.sh" ./dummy.ini orphan
+bash "${__root}/src/ini_val.sh" ./dummy.ini connection.host
+bash "${__root}/src/ini_val.sh" ./dummy.ini software.packages
+
+echo "--> command: Replace three values in-place and show result"
+bash "${__root}/src/ini_val.sh" ./dummy.ini orphan "no more"
+bash "${__root}/src/ini_val.sh" ./dummy.ini connection.host "192.168.0.1"
+bash "${__root}/src/ini_val.sh" ./dummy.ini software.packages "vim"
+cat dummy.ini
+rm -f dummy.ini
+
+# Use as include:
+cp -f data.ini dummy.ini
+source ${__root}/src/ini_val.sh
+echo "--> function: Read 3 values"
+ini_val ./dummy.ini orphan
+ini_val ./dummy.ini connection.host
+ini_val ./dummy.ini software.packages
+
+echo "--> function: Replace three values in-place and show result"
+ini_val ./dummy.ini orphan "no more"
+ini_val ./dummy.ini connection.host "192.168.0.1"
+ini_val ./dummy.ini software.packages "vim"
+cat dummy.ini
+rm -f dummy.ini