Are `less textfile | col` and `cat textfile` the same?

Question

Do less textfile | col and cat textfile accomplish the same thing?

I wonder if man mysql | col -b > textfile and man mysql > textfile do the same?

Answer 1

That's completely different, since less may do various kinds of transformation, e.g. via $LESSOPEN.

Answer 2

It's not quite the same, since when col can do something with output from less.

The important point here, less will copy input file to output if its output is not a tty. You can see in less-451 - main.c - line 222:

    /*
     * Set up terminal, etc.
     */
    if (!is_tty)
    {
        /*
         * Output is not a tty.
         * Just copy the input file(s) to output.
         */
        SET_BINARY(1);
        if (nifile() == 0)
        {
            if (edit_stdin() == 0)
                cat_file();
        } else if (edit_first() == 0)
        {
            do {
                cat_file();
            } while (edit_next(1) == 0);
        }
        quit(QUIT_OK);
    }

So, to do the same as cat file, you can:

less file | grep ^