Vi

From Ezee.co.uk

[edit] Search and replace

find each occurance of 'search' and replace it with 'replace' no confirmation prompts

:%s/search/replace/g           

find each occurance of 'search' and replace it with 'replace' with confirmation prompts

:%s/search/replace/gc

Find exact matches

:%s/<search>/replace/gc      

Case insensitive

:%s/search/replace/gci

Case sensitive

:%s/search/replace/gcI

The g means go do all of them, without this it would just do the first one