#10339: Simplify spkg/pipestatus
---------------------------------+------------------------------------------
Reporter: jdemeyer | Owner: GeorgSWeber
Type: defect | Status: closed
Priority: major | Milestone: sage-4.6.1
Component: scripts | Resolution: fixed
Keywords: pipestatus Makefile | Author: Jeroen Demeyer, Leif
Leonhardy
Upstream: N/A | Reviewer: Leif Leonhardy
Merged: sage-4.6.1.rc0 | Work_issues:
---------------------------------+------------------------------------------
Changes (by newvalueoldvalue):
* status: positive_review => closed
* resolution: => fixed
* author: Jeroen Demeyer => Jeroen Demeyer, Leif Leonhardy
Old description:
> spkg/pipestatus currently uses two different mechanisms, depending on the
> bash version. Unfortunately, the two alternatives differ in behaviour
> (the consequence is an {{{install.log}}} file appearing in the wrong
> place).
>
> Consider a command
> {{{
> pipestatus "A && B" "C"
> }}}
>
> Alternative 1 (for new versions of bash) does {{{A && (B | C)}}} while
> alternative 2 (for old versions of bash) does {{{(A && B) | C}}}.
>
> In my opinion, there should be only one alternative. If we have
> something which works for old versions, why not use that for new versions
> also?
>
> In any case, it would be good to think of a more robust implementation of
> pipestatus. I can think of the following:
> 1. Write a simple C program using pipe(), fork(), exec(), wait().
> 1. Use the `mkfifo` command.
> 1. Use a temporary file:
> {{{
> EXITSTATUS=/tmp/pipestatus$$ # Obviously, we should use TMPDIR if set
> ( A; echo $? >$EXITSTATUS ) | B
> }}}
> 1. Use `bash`'s `PIPESTATUS` array.
New description:
spkg/pipestatus currently uses two different mechanisms, depending on the
bash version. Unfortunately, the two alternatives differ in behaviour
(the consequence is an {{{install.log}}} file appearing in the wrong
place).
Consider a command
{{{
pipestatus "A && B" "C"
}}}
Alternative 1 (for new versions of bash) does {{{A && (B | C)}}} while
alternative 2 (for old versions of bash) does {{{(A && B) | C}}}.
The attached patch makes `pipestatus` behave like alternative 1 for
''all'' versions of `bash`.
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10339#comment:45>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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