> For what little it's worth, here's where this silly requirement can be found > (in case you're still looking for it): > > http://pubs.opengroup.org/onlinepubs/9699919799.2016edition/utilities/V3_chap01 As this is in the "introduction" section and there's a more precise (and more sensible) definition in 2.9.1, I would rather file an error with the Austin Group than trying to implement the words of 1.6.
To me, it looks like whoever wrote that final paragraph in the introduction messed up what I regard as two (or three) sub-categories of regular built-in-utilities (remember there are two other categories of "built-ins") -- alias/cd/ulimit et al, which can't sensibly be implemented externally -- true/false et al, which may regarded as so vital that you don't want PATH to mess them up and command/type, which you need to be built in to escape a messed up (or malicious) setup of PATH and function definitions (see the second example in the description of the "command" command).
