I'm one of those people who finds perverse pleasure in writing portable Bourne shell, and doing so correctly. I know I spend far more brain cycles on it than I

I'm one of those people who finds perverse pleasure in writing portable Bourne shell, and doing so correctly. I know I spend far more brain cycles on it than I should; once it gets past a certain complexity limit, I should just switch to Python. But I always say "It's just a little bit more code, there must be a good way to do this," and there generally is, but only after passing over several bad ways to do it first. Oh, and of course in doing so, I always try to minimize the amount of calling out to other processes. Why call awk when you could use `while read` instead? You only get one array to work with in portable Bourne shell, $@. You can parse lines using read, and strip prefixes and suffixes using parameter expansion (`${parameter%pattern}`). It's a restrictive little language, with a lot of quirks and edge cases, but it always makes a nice little challenge to figure out how you can use it safely. One of the constraints I impose is that spaces in pathnames should always be handled correctly; the biggest form of trouble you can easily get in is to forget to quote something or to parse something on space delimiters when it can include spaces. I've seen someone write a script that accidentally turned into an `rm -rf /path/to/important/data` because of poor handling of spaces. I generally do not attempt to handle newlines in pathnames. While it's possible to do so in some cases with null delimiters, I have never seen a case of newlines in pathnames in the wild. Of course, this means that I have to make sure that these scripts are never exposed to anything that could contain malicious filenames. Also, I move away from portable shell if it will really make the code too convoluted or fragile. For instance, if I need to parse long options (--foo), I use GNU getopt rather than the built-in getopts (with appropriate test to make sure the getopt I'm using is GNU, so it won't break silently on a system without GNU getopt), or move to a real language. Anyhow, while I know it's counterproductive, the puzzle-solving part of me really likes trying to solve the problem of implementing something in portable Bourne shell.