Script to search large documents and logs

Need a script written in a language (please recommend) to search for large text file (may be up to 1.5 GB), shell file (eg networking logs). Need custom field to add and remove keywords to search and also remove and replace option. This should be portable enough so that it can be distributed via email. Easy user interface is required. I also should be able to embed the script to Shell and should be able to find and find/replace option (linux terminal etc).