Re: reading from external command

[Peng Yu]

I am not sure what you are trying to do. But I see nothing in
/proc/self/task/. Did you assume a particular OS?

$ cat main.sh
#!/usr/bin/env bash
# vim: set noexpandtab tabstop=2:

x=( /proc/self/task/* )
$ ./main.sh
declare -a x=([0]="/proc/self/task/*")

On Wed, Mar 30, 2022 at 6:04 PM Alex fxmbsw7 Ratchev <fxmbsw7@gmail.com> wrote:
>
> bash peng
>
> 28250
> /dev/fd/63
> /dev/fd/63
> 41
> 44
> 44
>
> #!/bin/bash
>
> printf $$\\n
>
>  pid() {
> x=( /proc/self/task/* )
> printf %s\\n ${x##*/}
>  }
>
> >p
>  while read -r x ; do
> printf %s\\n <( pid >>p ; exit 44 )
>  done < <( pid >>p ; printf shit\\nbla\\n ; exit 41 )
>
>  while read -r p ; do
> wait $p
> echo $?
>  done <p
>
>
> On Thu, Mar 31, 2022 at 1:00 AM Lawrence Velázquez <vq@larryv.me> wrote:
> >
> > On Wed, Mar 30, 2022, at 6:32 PM, Peng Yu wrote:
> > > I am not sure how wait for "$!" would work robustly.
> > >
> > > In the following example, it can not get the error in the input.
> > >
> > > $ cat ./main.sh
> > > #!/usr/bin/env bash
> > > # vim: set noexpandtab tabstop=2:
> > >
> > > while read -r x; do
> > >       echo <(exit 42)
> > > done < <(
> > >       builtin printf '%s\n' a b c
> > >       false
> > > )
> > > wait "$!"
> > > echo "$?"
> > > $ ./main.sh
> > > /dev/fd/63
> > > /dev/fd/63
> > > /dev/fd/63
> > > 42
> >
> > Now you've gone and changed the problem by spinning off multiple
> > asynchronous commands at once.
> >
> > I don't know how robust this is, but at a minimum you need to access
> > $! before spawning the asynchronous commands you don't care about:
> >
> >     % cat main.bash; echo
> >     printf '%s\n' "$BASH_VERSION"
> >
> >     {
> >         pid=$!
> >         while read -r x; do
> >             echo <(exit 42)
> >         done
> >     } < <(builtin printf '%s\n' a b c; exit 99)
> >
> >     wait "$pid"
> >     echo "$?"
> >
> >     % bash main.bash
> >     5.1.16(1)-release
> >     /dev/fd/62
> >     /dev/fd/62
> >     /dev/fd/62
> >     99
> >
> > --
> > vq



-- 
Regards,
Peng