On Thu, May 26, 2022, at 10:39 PM, Christoph Anton Mitterer via austin-group-l at The Open Group wrote: > 2) The draft 2.1 says on page 2398 line 77766: > > The unset utility shall unset each variable or function definition > specified by name that does not > have the readonly attribute and remove any attributes other than > readonly that have been given to > name (see Section 2.14 export and readonly). > > To me that behaviour would seem quite odd ... and it doesn't match the > behaviour of at least bash and dash. > > > What the text currently says is: > `unset` unsets each var/function that is not readonly... > AND (with no further restriction) > removes all attributes other then readonly > (that is: whether or not the var is readonly). > > So that means: > export var=foo > readonly var > unset -v var > as per description, should leave var set (with value "foo"), should > leave the readonly attribute... but should remove the export attribute.
Seems that ksh93u+, mksh R59c, and yash 2.52 don't follow this interpretation either. > 3) It's IMO not fully clear whether a readonly variable is allowed to > have other attributes added (or cleared - see (2)). > > On page 2376, line 76926 says: > The values of variables with the readonly attribute cannot be changed > by subsequent assignment or use of the export, getopts, readonly, or > read utilities, nor can those variables be unset by the unset utility. > > and in fact, it seems to work with bash/dash to first mark a var > readonly (whether it's set or not) and then mark it as export. > > But still, given that the other way round seems to not work... it could > IMO deserve further clarification... and maybe emphasis, too, as > allowing to add further attributes is actually a bit contradicting the > read-only property, as it may change the behaviour. At a minimum, bash 5.1.16, ksh93u+, mksh R59c, dash 0.5.11.5, and yash 2.52 already allow exporting an existing readonly variable. If the standard ought to clarify anything, it's that the results of this action are unspecified. -- vq
