0001247: subshell execution environment and traps

Austin Group Defect Tracker

Aardvark Mark IV

Viewing Issue Simple Details [ Jump to Notes ]

[ Issue History ] [ Print ]

Category

Severity

Type

Date Submitted

Last Update

0001247

[1003.1(2016/18)/Issue7+TC2] Shell and Utilities

Editorial

Error

2019-04-19 02:08

2019-11-19 16:17

Reporter

kre

View Status

public

Assigned To

Priority

normal

Resolution

Accepted

Status

Applied

Name

Robert Elz

Organization

User Reference

Section

2.12

Page Number

2382

Line Number

76195-6, 76201-2

Interp Status

---

Final Accepted Text

Summary

0001247: subshell execution environment and traps

Description

XCU 2.12 (lines 76195-6) says:

     A subshell environment shall be created as a duplicate of
     the shell environment, except that signal traps that are
     not being ignored shall be set to the default action.

The issue is the word "signal" which could be read to imply that
EXIT traps (EXIT not being a signal) should not be reset to the
default in a subshell environment. No shell I have tested works
like that (nor would anyone expect, or want, them to). Less shells
support other non-signal traps, but the ones I have tested that
support ERR traps do not execute one of those set in the parent
shell when running in a subshell environment either. (I tested
numerous ways of producing a sub-shell environment for testing
EXIT traps, and none of them ran the trap, in any shell I tested.)

While in this paragraph, note that it ends (lines 76201-2) with
the sentence:

    All other commands shall be executed in the current
    shell environment.

After having listed a selection of commands that do not
(or might not, in the case of pipes) run in the current
execution environment. Yet section 2.9 (line ) says:

   If there is no command name, any redirections shall be
   performed in a subshell environment;

which is an empty simple command with redirects. That case
is not mentioned in the list of cases which use a subshell
environment in 2.12, contradicting the "All other" words.

Rather than attempt to list every place where the standard
might now, or in the future, require a sub-shell environment,
a better solution might just be to qualify the "All" to make
it clear than any other place the standard requires a subshell
environment is also to have one.

Desired Action

In line 76196 delete the word "signal".

In line 76201, delete the word "All" at the beginning of
the sentence "All other commands..." and replace it with
"Except where otherwise stated, all".

Issue History
Date Modified	Username	Field	Change
2019-04-19 02:08	kre	New Issue
2019-04-19 02:08	kre	Name	=> Robert Elz
2019-04-19 02:08	kre	Section	=> 2.12
2019-04-19 02:08	kre	Page Number	=> 2382
2019-04-19 02:08	kre	Line Number	=> 76195-6, 76201-2
2019-06-27 16:10	Don Cragun	Interp Status	=> ---
2019-06-27 16:10	Don Cragun	Status	New => Resolved
2019-06-27 16:10	Don Cragun	Resolution	Open => Accepted
2019-06-27 16:10	Don Cragun	Tag Attached: tc3-2008
2019-11-19 16:17	geoffclare	Status	Resolved => Applied

Relationships