That's because the amount of data in total that will be written is totally irrelevant to -B.
It should be highlighted that the input buffer should be very large (e.g. 4M) to take advantage of modern hardware I/O speeds, and for most uses mm(1) is better.
Again, this commenting is bad. C isn't its preprocessor. If this kind of commenting is needed I would straight-up rather remove C from this project than continue with it. The alternative to do/whiles is infinite loops with conditions at the end which are what do/whiles exist to solve. Commenting the function of basic C language features clutters code significantly.
Moving this comment makes it wrong. This ternary makes sure strtol(3p) succeeded. *s == 0, which is on its own vague, checks if no chars are left unparsed.
getopt(3p) will still happen when argc==0. And dj(1) should run when argc<0. If the user's system is broken, don't deny them the basic tools to fix it.
This shouldn't be required. Typos are easy to spot in Rust and I believe C disallows this.
This should stay that way because it's somewhat common practice among greybeards (I know many in the 9front community do it).
It should be highlighted that the input buffer should be very large (e.g. 4M) to take advantage of modern hardware I/O speeds, and for most uses mm(1) is better.
This should be -1. While it is in reality 255, the negative is consistent with strcmp(3p) and may be useful on certain systems. Also, at some point retvals here should be more significant.