[Buildroot] [PATCH 1/2] busybox: add /dev/std{in, out, err} symlinks to inittab

Jörg Krause joerg.krause at embedded.rocks
Wed Apr 4 18:09:34 UTC 2018


Some applications, e.g. bashs process subsitution feature, rely on the
convention of `/dev/fd` being a symbolic link to `/proc/self/fd`.

This symbolic link and his companions `/dev/std*` are created by (e)udev [1],
but not by mdev, resulting in the following error when using the following
expression:

```
bash: /dev/fd/62: No such file or directory
```

For the sake of simplicity, lets fix this by creating the symlinks in inittab.
It is only really needed if eudev isn't used, but it doesn't really hurt to
create them even if eudev will recreate them afterwards.

Note, that we do not create the symlink `/dev/core` as `/proc/kcore` is
not available on all platforms, e.g. ARM, and the feature is not much
appreciated [2].

[1] https://github.com/gentoo/eudev/blob/8943501993322c59a6eb5be456b0d716aafff21e/src/shared/dev-setup.c#L35-L40
[2] https://lwn.net/Articles/45315/

Signed-off-by: Jörg Krause <joerg.krause at embedded.rocks>
---
 package/busybox/inittab | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/package/busybox/inittab b/package/busybox/inittab
index 3f49f6bd7a..0f6b8cbe37 100644
--- a/package/busybox/inittab
+++ b/package/busybox/inittab
@@ -19,6 +19,10 @@
 ::sysinit:/bin/mkdir -p /dev/pts
 ::sysinit:/bin/mkdir -p /dev/shm
 ::sysinit:/bin/mount -a
+::sysinit:/bin/ln -sf /proc/self/fd /dev/fd
+::sysinit:/bin/ln -sf /proc/self/fd/0 /dev/stdin
+::sysinit:/bin/ln -sf /proc/self/fd/1 /dev/stdout
+::sysinit:/bin/ln -sf /proc/self/fd/2 /dev/stderr
 ::sysinit:/bin/hostname -F /etc/hostname
 # now run any rc scripts
 ::sysinit:/etc/init.d/rcS
-- 
2.16.3



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