Not today...

This is just a problem I encountered running my Alpine box, so I publish the fix for others to not loose time like I did. I had a software that came with a bash script and got a problem when I tried to run it. It was failing with the following error: fopen: No such file or directory

I added the magical set -x line at the beginning to understand what was going on. I re-ran the script and saw the following output:

+ wg setconf wg0 /dev/fd/63
fopen: No such file or directory

I checked the script to retrieve the line and here is what was written:

cmd wg setconf "$INTERFACE" <(echo "$WG_CONFIG")

The problem is coming from the process substitution part. I quickly checked that it was really what I was suspecting:

# ensure I am properly using bash first since ash do not support process substitution
/bin/bash

# this should echo something like 5.0.17(1)-release
echo $BASH_VERSION

# testing process substitution
cat <(echo "foo")

I got the same error: fopen: No such file or directory. I then search the Internet for an answer and finally found this issue. I quickly ran through it and found out that it can be fixed by creating a symlink: ln -snf /proc/self/fd /dev/fd.

Important: be sure that /dev/fd does not exist before running the command, otherwise, you will end up with /dev/fd/fd.