Match portion of the filename

Shell Programming and Scripting
1

hi,
I have a script which accept filename and process them, however, one of the file needs 'special' handling so I need to identify it, say the filename contains the word "STOCK" (i.e. NEWYORKSTOCKLIST20060627.txt), I want to check if the filename contains the word "STOCK", how can I do that? thanks

2 
if [[ "$filename" == *STOCK* ]] ; then
  echo "STOCK file"
fi ;