helpThe GNU Bourne-Again SHell - Support: sr #109046, Should `(set -p)` (at least in...


sr #109046: Should `(set -p)` (at least in POSIX mode) list background jobs of parent environment?

Submitted by:  Geoff Nixon <gsnixon>
Submitted on:  Thu 19 May 2016 12:57:50 AM UTC  
Category:  None Priority:  5 - Normal
Severity:  3 - Normal Status:  Wont Do
Privacy:  Public Assigned to:  None
Open/Closed:  Open Operating System:  *BSD

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Wed 03 Aug 2016 08:00:17 PM UTC, comment #1:

They don't inherit jobs because those jobs are not children of the subshell begin to run the (...), and that shell instance can't get notified when they change state. There is special-case code to allow $(jobs -p) because that seems to be generally useful and requested. I don't see the same need to special-case (...) subshells.

Chet Ramey <chet>
Project Administrator
Thu 19 May 2016 12:57:50 AM UTC, original submission:

Hi Chet (et al),

I was wondering what your thought is on this recent issue I've revived about `dash`:

Particularly, the bit about how in bash (with or without POSIX mode enabled), explicit subshells of the `(...)` variety inherit most of the parent shell's environment, including unexported variables, etc., but not "asynchronous lists".

In other words, in ksh93, pdksh, mksh, oksh, and yash, the output of `(jobs -p)` is the same as `echo $(jobs -p). But not in bash (or busybox ash).

As I read it, I can't seem to find in the POSIX standard why/how `(...)` subshells should not inherit the jobs list, but `$(...)` subshells should. What's your interpretation here?


Geoff Nixon <gsnixon>


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