Ya know, if you are looking for optimization opportunities, using
a temporary file to communicate between processes rather than
using an actual pipe, is definitely a performance hit --
ESPECIALLY on Cygwin, where you can't even do a "stat" call on
a file without actually opening the file.
I seem
On 10/11/16 10:14 PM, s7v7nisla...@gmail.com wrote:
> 1. the script to reproduce
> bash-4.4$ cat t.sh
> (cd /tmp && sleep 20) &
>
> echo "end"
>
>
> 2. run it
> bash-4.4$ bash t.sh
> end
>
> 3. script end, but there is a new forked script.
> bash-4.4$ ps -ef | grep t.sh
> 501 50268 1
Daniel Colascione wrote:
On 10/15/2016 12:23 AM, L. A. Walsh wrote:
Daniel Colascione wrote:
One such case is Cygwin --- I'm not sure how "contrived" it is. Cygwin
has an old-fashioned non-COW fork, and to add insult to injury,
process creation generally is very slow (~100ms). It pays to elim
XiaoBing Jiang wrote:
Thank you for your explain!
#!/bin/bash
(cd /tmp && exec sleep 20) &
echo "end"
Then, instead of having:
$ ./foo
end
$ ps f -t pts/5
PID TTY STAT TIME COMMAND
7287 pts/5Ss 0:00 bash
20165 pts/5R+ 0:00
On 10/15/2016 12:23 AM, L. A. Walsh wrote:
Daniel Colascione wrote:
One such case is Cygwin --- I'm not sure how "contrived" it is. Cygwin
has an old-fashioned non-COW fork, and to add insult to injury,
process creation generally is very slow (~100ms). It pays to eliminate
subshells in that en
Daniel Colascione wrote:
One such case is Cygwin --- I'm not sure how "contrived" it is. Cygwin
has an old-fashioned non-COW fork, and to add insult to injury,
process creation generally is very slow (~100ms). It pays to eliminate
subshells in that environment.
Given what Cygwin has to work
On 10/13/2016 08:05 PM, Bob Proulx wrote:
XiaoBing Jiang wrote:
Greg Wooledge wrote:
If you want to ENSURE that the child shell process is replaced by the
external sleep 20, use an explicit exec.
yes, I want to know why bash not optimize this. or any strategy ?
Because it wouldn't save anyt
XiaoBing Jiang wrote:
> Greg Wooledge wrote:
> > If you want to ENSURE that the child shell process is replaced by the
> > external sleep 20, use an explicit exec.
>
> yes, I want to know why bash not optimize this. or any strategy ?
Because it wouldn't save anything significant. Since the parent
On Wed, Oct 12, 2016 at 8:23 PM, Greg Wooledge wrote:
> On Tue, Oct 11, 2016 at 07:14:24PM -0700, s7v7nisla...@gmail.com wrote:
> > why bash bahavior like this? is that a bug?
> >
> > if not, why should forked before execute subshell?
>
> Because that's how subshells work. A subshell *is* a fork
On Tue, Oct 11, 2016 at 07:14:24PM -0700, s7v7nisla...@gmail.com wrote:
> why bash bahavior like this? is that a bug?
>
> if not, why should forked before execute subshell?
Because that's how subshells work. A subshell *is* a fork.
> 1. the script to reproduce
> bash-4.4$ cat t.sh
> (cd /tmp &
1. the script to reproduce
bash-4.4$ cat t.sh
(cd /tmp && sleep 20) &
echo "end"
2. run it
bash-4.4$ bash t.sh
end
3. script end, but there is a new forked script.
bash-4.4$ ps -ef | grep t.sh
501 50268 1 0 10:09AM ttys0150:00.00 bash t.sh
501 50275 50181 0 10:10AM ttys015
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