Question

 "sed \'s/\t/ /g\' "

Thank you! It is part of code like this

string cmd = "sed \'s/\t/ /g\' " + string(filename) + " > sample.clean";
            system(cmd.c_str());
            ifstream infile("sample.clean");
            if (!infile){
                cerr << "error loading file after clean-up!\n";
                return 0;
            }

Answer 1

It replaces tabs with spaces, but it does so poorly. Within sed itself, 'y/\t/ /' is better, but sed is the wrong tool and it is even better written tr '\t' ' '