[Buildroot] bash: /dev/fd/62: No such file or directory

[Peter Korsgaard <peter@korsgaard.com>]

>>>>> "J?rg" == J?rg Krause <joerg.krause@embedded.rocks> writes:

 > Hi,
 > I am facing an issue with busybox init system, bash and mdev. When a
 > bash script uses process substitution, bash ends with an error:

 >    """
 >    # bash -c 'read x< <(echo 1); echo $x'
 >    bash: /dev/fd/62: No such file or directory
 >    """

 > The issue is addressed is some threads, e.g. [1]. The problem is that
 > /dev/fd does not exist when using mdev:

So that is really strictly seen a bug in bash. The /dev/fd convenience
symlink is afaik a convention from udev/systemd.

But OK, bash might not be alone and the pragmatic solution would indeed
be to create these symlinks ourselves in the busybox and sysvinit
inittabs, similar to how we create /dev/pts and /dev/shm.

It is only really needed if (e)udev isn't used, but it doesn't really
hurt to create them even if eudev will recreate them afterwards.

Keep in mind that we still support a static /dev, so we should also add
them to system/device_table_dev.txt and redirect errors to /dev/null so
you don't get a bunch of warnings about these symlinks when booting with
a static /dev.

Notice that it isn't only about /dev/fd. From
eudev-3.2.5/src/shared/dev-setup.c:

        static const char symlinks[] =
                "-/proc/kcore\0"     "/dev/core\0"
                "/proc/self/fd\0"    "/dev/fd\0"
                "/proc/self/fd/0\0"  "/dev/stdin\0"
                "/proc/self/fd/1\0"  "/dev/stdout\0"
                "/proc/self/fd/2\0"  "/dev/stderr\0";

There is some logic to only create /dev/core if /proc/kcore exists, but
I think we can just create it unconditionally.

Care to send patches doing this?

-- 
Bye, Peter Korsgaard