How can i turn this into a rewrite i have include what i have tried

for example you have www.example.com/test/c_index.shtml

you click a the change language button and the url changes to www.example/com/test/c_index.shtml?change_lang

so i would like to rewrite that to www.example.com/test/e_index.shtml

I have tried

rewrite /test/c_(.*)\?change_lang /test/e_$1 redirect;

but that doesnt work

Any help would be much appreciated