Hoi. [2018-07-16 20:56] Vasilii Kolobkov <polezaivs...@ko5v.net> > [2018-07-16 12:23 +0200] markus schnalke <mei...@marmaro.de> > > [2018-07-15 23:29] Vasilii Kolobkov <polezaivs...@ko5v.net> > > > 1. Generate sequences vi shell script as BSDs lack seq(1) > > > > That's unfortunate, as seq(1) is such a great tool. It's not part > > of POSIX though. (It originated in Research Unix after v7, i.e. on > > the way to Plan 9 but after the SystemV and BSD have split off, IIRC.) > > Yeah, read something like 'in Linux you do `seq 1 10` and in BSDs > - `jot 10 1`'. Guess you got to learn to appreciate the fun bits > like that, even if just to keep your nervous system intact when > doing cross-platform stuff.
> Enough ground to keep a software anthropologist busy for a long > while, heh? til, just keep interval expressions out of awk programms. Yeah, an interesting topic in itself, this Unix history stuff. I like it a lot. Of course, it makes portability a difficult job. But, now that we have POSIX ... okay wait: eventually, when all systems will implement it ... ;-P > > Although $((...)) ist part of POSIX. I'd like to avoid it, if > > possible. All uses of $((...)) in our test cases can be easily > > converted to expr(1). Would that be okay for you or do do you have > > strong opinions pro $((...))? > > I hold no special feeling about arithmetic expressions in sh(1) - > they do get clunky fast, but i still prefer shell constructs to > involving some heavy hitters like awk. Mind sharing why you choose > against them? POSIX's goal was to document the common behavior across various Unix derivates. In situations, when different, incompatible behavior was present, it sometimes chose one of the alternatives or none, if one could live without. For the most part, it refused to standardize new behavior, especially if there was no important reason to do so. To me, arithmetic expressions in sh are kind of superfluous. There already exist alternatives in POSIX that are older and more widespread: expr(1) for the simple stuff, bc(1) for the complex stuff, test(1) for boolean, and awk(1) for the full power of $((...)). Their only downside is time performance, which I hardly like to accept as a good motivation. Arithmetic expressions are an extension of the shell command language, which introduces new syntax and a new thinking model, whereas there already existed solutions, which either fitted into the existing thinking model (expr(1), test(1)) or already introduced new thinking models (bc(1), awk(1)). IMO arithmetic expressions were unnecessary to add (from the Unix standard shell POV (not from David Korn's POV, as I like to admit)). (Even more, their syntax is badly chosen, as it is too close to $(...) and (...).) These are (conceptual) reasons I don't like arithmetic expressions. And, of course, old shells don't support them. Which is a (increasingly less important) practical reason. > The tr|sed|nl is such nice little gem i'd definitely go with it, > readability objections well deserved still. The coolnes factor is definitely high. ;-) It's only acceptable if it is wrapped in a function with a name that clearly describes what's going on. > I'd rate the given options (in order of descending preference) - > 1. tr|sed|nl 2. sh w/ expr(1) and 3. awk. What about you? First step, I'd say: Write some enum() or countto() or even still name it seq() function in test/common.sh, which only accepts a single argument and does what seq(1) does if it has exactly one argument. Then use this helper function in the test cases. The actual implementation becomes a minor topic thus. We can change it easily then. > I believe it'll be best to keep this last patch as a draft and i'll > keep adding more fixes to it. Yes, keep going! Definitely worthwhile, your work! meillo
