Shellshock check for bashrc

.bashrc

# To anyone worried about using servers that may not have attentive admins --
# put the following line(s) in your ~/.bashrc to help protect yourself:

env x='() { :;}; echo "WARNING: SHELLSHOCK DETECTED"' \
    bash --norc -c ':' 2>/dev/null;

# It will print to stdout if and only if your shell is vulnerable, and nothing
# will be printed if your shell has been patched. It will take a little longer
# to launch a new shell slightly, but for some, this may be worth it.

if you are concerned about different bash versions on the system you might try to catch them all with something like

for exe in `which -a sh bash`; do
  env x='() { :;}; echo "WARNING: SHELLSHOCK DETECTED in '$exe'"' \
    $exe --norc -c : 2>/dev/null
done

Here, let's include ${BASH}, dedup the list, and add extra quotes for crazy people with whitespace in their filenames:

# Shellshock test 
count=$( (echo ${BASH};which -a bash sh ) | sort -u | wc -l)
for (( a=1 ; $a<=$count; a=$a+1 )); do
  exe="$((echo ${BASH};which -a bash sh ) | sort -u | head -$a | tail -1)"
  env x='() { :;}; echo "WARNING: SHELLSHOCK DETECTED in $exe"' "$exe" --norc -c : 2>/dev/null
done
unset count exe a

Note: it turned out to be fiendishly hard to deal with whitespace in $BASH and $PATH.