function [output_file]=clean_files(input_dir,filename,ext4,find_str,replace_str,output_dir);
% Searches a text file for the TARGET string find_str
% Replaces it with replace_str, and writes the output file.
% find_str = '---.---';
% replace_str = '';
% filename = 'testfile';
% ext4 = '.csv';

% ALGORITHM
% Parse file by reading 1 line at a time,
% see if that line has the offending string using STRFIND, else write it
% If it does, remove it, then write the remainder.
% NOTE: the offending string will be assumed to never be in the 1st
% position, but may occur more than once otherwise.
output_file = [filename,'C'];

if ~exist([output_dir,output_file,ext4])
    fid = fopen([input_dir,filename,ext4]);
    alldata = fscanf(fid,'%s');
    ismatch = strfind(alldata,find_str);
    if isempty(ismatch)
        eval(['!cp ',input_dir,filename,ext4,' ',output_dir,output_file,ext4]);
    else
        fclose(fid);
        fid=fopen([input_dir,filename,ext4]);
        fid2 = fopen([output_dir,output_file,ext4],'w');

        isendoffile=0;
        while isendoffile==0
            OneLine = fgetl(fid);
            matches = strfind(OneLine, find_str);
            if ~isempty(matches)
                OneLine = remove_str(OneLine,find_str,replace_str,matches);
                fprintf(fid2,'%\n',OneLine);
            elseif length(OneLine)<2
                isendoffile=1;
            else
                fprintf(fid2,'%s\n',OneLine);
            end
        end
        fclose(fid);
        fclose(fid2);
    end
end