> but on my system for example, it's 128k. Never ran into this problem. That may be because of decades of defence against it. For example, the naive way to run

> but on my system for example, it's 128k. Never ran into this problem. That may be because of decades of defence against it. For example, the naive way to run foo on all your .c files in one go is: find . -type f -name "*.c" -exec foo {} \+ (aside: also note that I had to escape the + at the end of the command. RANT: of course, man find doesn’t mention that, as that’s a shell issue that has nothing to do with find. Technically correct, but beginning users will be baffled) In my home directory, that’s about a megabyte of arguments, so I have to fall back to find . -type f -name "*.c" -exec foo {} \; which calls foo thousands of times, to invoking xargs, or to some other workaround. Either way, foo is called more than once, so the result may not be what I expected. For real-world examples, see - https://stackoverflow.com/questions/55453993/argument-list-too-long-error-for-find-command https://stackoverflow.com/questions/55453993/argument-list-t... - https://www.linuxquestions.org/questions/linux-software-2/argument-list-too-long-why-am-i-getting-this-with-the-find-command-585622/ https://www.linuxquestions.org/questions/linux-software-2/ar... - https://www.baeldung.com/linux/argument-list-too-long-error https://www.baeldung.com/linux/argument-list-too-long-error > You'd probably make it so that it has its own parsing too in that case, so you can do calc '3 * 4 + 5’ That’s what you would do, yes, but that’s not ideal, and won’t work well if you want to write a one-liner for a tool whose language can contain single quotes, such as sed/awk/perl/…. > Hmmm, does it create the output file first and then expand the arguments? Yes, it does. It all works, but isn’t ideal, and I think using a library to do argument parsing would help here (variable expansion may be a problem when doing that, though, as postponing that till after the tool runs may introduce a race condition when running a tool in the background. If that is a problem at all, I think that’s solvable, though)