Bash Process Substitution with WSL-CodePudding

I am trying to understand the following (odd?) behavior on my setup. I am running Windows 10, with WSL.

Here is what I see from my powershell wsl session:

$ ./run.sh

Windows IP Configuration
<cut>
1

with:

$ cat run.sh
#!/bin/bash

mkdir -p dir/1
mkdir -p dir/2
mkdir -p dir/3

var=0
while read i;
do
  ((var  ))
  ipconfig.exe
done < <(find dir -type d)

echo $var

If I now comment out the ipconfig.exe line:

...
  #ipconfig.exe
...

Here is now what I get:

$ ./run.sh
4

Why calling a window executable (eg. ipconfig.exe) seems to interfere with my while loop) ?

For reference:

$ uname -a
Linux FR-L0002146 5.10.102.1-microsoft-standard-WSL2 #1 SMP Wed Mar 2 00:30:59 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

and

$ bash -version
GNU bash, version 5.0.17(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2019 Free Software Foundation, Inc.
License GPLv3 : GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

CodePudding user response：

Most likely ipconfig.exe is reading from stdin, so it's sucking up the input from the process substitution. Redirect its input to /dev/null to prevent this.

while read i;
do
  ((var  ))
  ipconfig.exe </dev/null
done < <(find dir -type d)