http://www.gnu.org/prep/standards/html_node/Reading-Non_002dFree-Code.html http://www.gnu.org/prep/standards/html_node/Reading-Non_002d... Don't in any circums

http://www.gnu.org/prep/standards/html_node/Reading-Non_002dFree-Code.html http://www.gnu.org/prep/standards/html_node/Reading-Non_002d... Don't in any circumstances refer to Unix source code for or during your work on GNU! (Or to any other proprietary programs.) If you have a vague recollection of the internals of a Unix program, this does not absolutely mean you can't write an imitation of it, but do try to organize the imitation internally along different lines, because this is likely to make the details of the Unix version irrelevant and dissimilar to your results. For example, Unix utilities were generally optimized to minimize memory use; if you go for speed instead, your program will be very different. You could keep the entire input file in memory and scan it there instead of using stdio. Use a smarter algorithm discovered more recently than the Unix program. Eliminate use of temporary files. Do it in one pass instead of two (we did this in the assembler).