Shell Programming and Scripting

I have 2 files: fileA and fileB.

content of fileA
---------------
admin.teacher is in new york;
admin.mason is in new york;
admin.driver is in new york city;
user.trucker is in hartford;
admin.developer is in new york state;

content of fileB
----------------
admin.teacher is in chigago;
user.teacher is in new york;
admin.mason is in new york;
admin.developer is in new york state
admin.plumber is in new york;
admin.driver is in new york city;
user.trucker is in hartford;
admin.nurse is in new york state;
admin.teacher is in new york
user.painter is in new york;


This is what I am trying to achieve:
I would like to loop through fileB and if any member in fileA
is found in fileB then that line in fileB will be commented with (--)
I am looking for a neat script to do this for me. thx.

This means that the resulting file to look like:

FileC
----------
admin.teacher is in chigago;
user.teacher is in new york;
--admin.mason is in new york;
--admin.developer is in new york state
admin.plumber is in new york;
--admin.driver is in new york city;
--user.trucker is in hartford;
admin.nurse is in new york state;
--admin.teacher is in new york
user.painter is in new york;

Moderator's Comments:

Double Post. Closed.

By "member" you mean whole lines to be the same? Or just the first column?

below code is match by whole line.

Code:

awk 'NR==FNR{a[$0]++;next} a[$0]{$0="--"$0}1' fileA fileB

below code is match by member.

Code:

awk 'NR==FNR{a[$1]++;next} a[$1]{$1="--"$1}1' fileA fileB