Tools: add run-shellcheck.sh to statically analyze startup scripts

Use './Tools/run-shellcheck.sh ROMFS/px4fmu_common' to run it.

Tools/run-shellcheck.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+
+# Script to run ShellCheck (a static analysis tool for shell scripts) over a
+# script directory
+
+if [ -z "$1" ]; then
+	echo "usage: $0 <directory>"
+	echo ""
+	echo "  <directory>     Directory to search for scripts"
+	exit -1
+fi
+search_directory="$1"
+
+command -v shellcheck >/dev/null 2>&1 || { echo -e >&2 \
+"Error: shellcheck required but it's not installed. On Ubuntu use:\n sudo apt-get install shellcheck\n\nAborting."; exit 1; }
+
+scripts="$(find "$search_directory" -type f ! -name '*.txt' ! -name '*.mix')"
+
+echo "Running shellcheck in '$search_directory'."
+
+# Disabled rules:
+# SC2121: allow 'set' as assignment (NuttX-style)
+# SC1008: unrecognized shebang
+# SC2086: double quote to prevent globbing and word splitting
+# SC2166: allow the form [ $OUTPUT_MODE == fmu -o $OUTPUT_MODE == io ]
+# SC2148: allow files w/o shebang
+shellcheck -a -x -e SC2121 -e SC1008 -e SC2086 -e SC2166 -e SC2148 \
+	$scripts
+ret=$?
+if [ $ret -ne 0 ]; then
+	echo "Please fix the above script problems."
+	echo "If an error is raised that should be ignored, \
+add the following right before the offending line:"
+	echo "# shellcheck disable=SCxxxx"
+	echo ""
+	echo "Re-run the script with '$0 $@'"
+	exit $ret
+fi
+
+echo "No problems found."
+exit 0