IMP: new tag in file to tell that the script should pass shellcheck

The `# run-shellchek` tag must be placed in the first 10 lines of the
file

shellcheck/docker_build_and_run_shellcheck.sh

@@ -1,4 +1,7 @@
 #!/bin/bash
+# run-shellcheck
+# usage : $0 [shell script to check]
+# called without arguments, il will shellcheck any *.sh file found in the project
 set -e
 
 dockerfile="$(dirname "$0")/Dockerfile.shellcheck"

shellcheck/launch_shellcheck.sh

@@ -1,7 +1,9 @@
 #!/bin/bash
-
+# run-shellcheck
+# please do not run this script directly but `docker_build_and_run_shellcheck.sh`
 
 files=""
+retval=0
 
 if [ $# -eq 0 ]; then
     files=$(find . -name "*.sh")
@@ -10,6 +12,11 @@ else
 fi
 
 for f in $files; do
-    printf "\e[1;36mRunning shellcheck on: %s  \e[0m\n" "$f"
-    /usr/bin/shellcheck --color=always --external-sources --shell=bash "$f"
+    if head "$f" | grep -qE "^# run-shellcheck$"; then
+        printf "\e[1;36mRunning shellcheck on: %s  \e[0m\n" "$f"
+        if ! /usr/bin/shellcheck --color=always --external-sources --shell=bash "$f"; then
+            retval=$((retval + 1))
+        fi
+    fi
 done
+exit "$retval"