On 2019-11-13 at 11:30 -0500, Chet Ramey wrote: > On 11/13/19 10:59 AM, Shaun Crampton wrote: > > But the commands in the subshell execute inside a different shell > > execution context so they shouldn't have > > their own set -e context (Section 2.12)? > > Why? That section says the only thing that changes in the subshell > environment is signal dispositions. > > In fact, the example in the set builtin description explicitly assumes > the subshell inherits the errexit setting. The only thing the standard > requires here is that setting -e in the subshell doesn't change the > parent's setting. > > But that's not exactly the point. The shell is "executing any command of an > AND-OR list other than the last" so errexit is ignored.
I would say that the confusing part is that the behavior of the subshell is dependant on *where* it is being executed in the parent. In general terms, I would expect ( <code> ) to be roughly equivalent to bash -c "<code>" i.e. <code> being executed on its own context and unable to affect the parent but the provided case shows that ( set -e; false; echo here ) && echo bar behaves differently than bash -c "set -e; false; echo here" && echo there since the initial subshell has an advanced knowledge that there will be a later command joined by an and. And the fact that reversing the order echo hello && ( set -e; false; echo here ) gives a different result, as it is now the *final* element of the && list. The joys of set -e https://mywiki.wooledge.org/BashFAQ/105, already mentioned in the thread gives a «funny» read of these things. Kind regards
