def do_path_regex_sub(self, pathexp, regexp, subst):
        '''Apply a regexp substituation to a set of files archived by
        sos. The set of files to be substituted is generated by matching
        collected file pathnames against pathexp which may be a regular
        expression string or compiled re object. The portion of the file
        to be replaced is specified via regexp and the replacement string
        is passed in subst.'''
        if not hasattr(pathexp, "match"):
            pathexp = re.compile(pathexp)
        match = pathexp.match
        file_list = [f for f in self.copied_files if match(f['srcpath'])]
        for file in file_list:
            self.do_file_sub(file['srcpath'], regexp, subst)
Apply a regexp substituation to a set of files archived by
        sos. The set of files to be substituted is generated by matching
        collected file pathnames against pathexp which may be a regular
        expression string or compiled re object. The portion of the file
        to be replaced is specified via regexp and the replacement string
        is passed in subst.