Parse user arguments, before exiting on arguments missing

Previously, it was not possible to read the help text, without having defined
certain user variables the script needs (like MENDER_ARTIFACT_NAME). Thus
reading the usage help-info was sort of tedious.

This commit gives the user commands higher priority, which fixes the error.

Changelog: None

Signed-off-by: Ole Petter <ole.orhagen@northern.tech>

mender-convert

@@ -54,22 +54,6 @@ function trap_term() {
 trap trap_term INT TERM
 trap trap_exit EXIT
 
-mender_convert_dir=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
-if [ "${mender_convert_dir}" != "${PWD}" ]; then
-    echo "You must execute mender-convert from the root directory: ${mender_convert_dir}"
-    exit 1
-fi
-
-if [ -z "${MENDER_ARTIFACT_NAME}" ]; then
-  echo "Sorry, it seems that you have not defined MENDER_ARTIFACT_NAME"
-  echo "You can do this with the following command:"
-  echo ""
-  echo -e "\tMENDER_ARTIFACT_NAME="release-1" ./mender-convert"
-  exit 1
-fi
-
-source modules/bootstrap.sh
-
 # We only handle a selection of the arguments here, the rest are passed on
 # to the sub-scripts.
 while (( "$#" )); do
@@ -88,6 +72,22 @@ while (( "$#" )); do
     esac
 done
 
+mender_convert_dir=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
+if [ "${mender_convert_dir}" != "${PWD}" ]; then
+    echo "You must execute mender-convert from the root directory: ${mender_convert_dir}"
+    exit 1
+fi
+
+if [ -z "${MENDER_ARTIFACT_NAME}" ]; then
+  echo "Sorry, it seems that you have not defined MENDER_ARTIFACT_NAME"
+  echo "You can do this with the following command:"
+  echo ""
+  echo -e "\tMENDER_ARTIFACT_NAME="release-1" ./mender-convert"
+  exit 1
+fi
+
+source modules/bootstrap.sh
+
 mkdir -p work
 touch work/convert.log