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Re: is there a way to save stdout and stderr to two bash variables?
From: |
Chet Ramey |
Subject: |
Re: is there a way to save stdout and stderr to two bash variables? |
Date: |
Tue, 12 May 2020 09:52:46 -0400 |
User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 |
On 5/12/20 5:44 AM, Peng Yu wrote:
> Also, if you do not allow even internal usages of external files at
> all, you cannot use here documents and here strings as they also use
> temporary files internally. For example, you can confirm this by the
> following command.
>
> $ ls -la /dev/fd/0 <<< Here
> lr-x------. 1 murase murase 64 2020-05-12 09:42:22 /dev/fd/0 ->
> /tmp/sh-thd.ZLmXgN (deleted)
>
>
> I didn’t know that this was the case. I always thought heredoc was in memory.
That's not a good assumption. This list has seen a dozen discussions of the
historical bash implementation of here docs and here strings.
> Chet, There was not an in memory implementation of here doc possible in
> bash? How much performance difference it could be comparing in memory and
> temp file (suppose temp file is not in a RAM disk)?
You have to turn that memory into a file descriptor. There are a few ways
to do that: a temp file, a pipe, and mmap-style file mapping (which
requires a file and file descriptor anyway). The devel branch uses pipes
if the here document or here string is smaller than the pipe size, and
a temp file otherwise.
There was a long discussion about this a year ago, starting with
https://lists.gnu.org/archive/html/bug-bash/2019-04/msg00007.html
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU address@hidden http://tiswww.cwru.edu/~chet/
- Re: is there a way to save stdout and stderr to two bash variables?, (continued)
- Re: is there a way to save stdout and stderr to two bash variables?, Koichi Murase, 2020/05/11
- Re: is there a way to save stdout and stderr to two bash variables?, Peng Yu, 2020/05/11
- Re: is there a way to save stdout and stderr to two bash variables?, Koichi Murase, 2020/05/11
- Re: is there a way to save stdout and stderr to two bash variables?, Greg Wooledge, 2020/05/11
- Re: is there a way to save stdout and stderr to two bash variables?, Peng Yu, 2020/05/12
- Re: is there a way to save stdout and stderr to two bash variables?, Andreas Kusalananda Kähäri, 2020/05/12
- Re: is there a way to save stdout and stderr to two bash variables?, Peng Yu, 2020/05/12
- Re: is there a way to save stdout and stderr to two bash variables?, Tim Visher, 2020/05/12
- Re: is there a way to save stdout and stderr to two bash variables?, Pier Paolo Grassi, 2020/05/12
- Re: is there a way to save stdout and stderr to two bash variables?, Chet Ramey, 2020/05/12
- Re: is there a way to save stdout and stderr to two bash variables?,
Chet Ramey <=
- Re: is there a way to save stdout and stderr to two bash variables?, Peng Yu, 2020/05/12
- Re: is there a way to save stdout and stderr to two bash variables?, Chet Ramey, 2020/05/12
- Re: is there a way to save stdout and stderr to two bash variables?, Peng Yu, 2020/05/12