[Buildroot] udevadm: missing or unknown command

[Nimai Mahajan <nimaim@gmail.com>]

Steve Kenton <skenton@...> writes:

> 
> I have an (x86) application where the end 
users can hot plug disks drives.
> Since I have no control over what they put 
where, labels etc are of limited use
> so I switched from mdev to eudev so I could 
match the actual SATA port in use
> These rules added to a file in 
/etc/udev/rules.d seem to do the trick
> 
> # Bind the drive names to the physical port 
they connect too - udev no longer allow renaming 
device nodes so
> set up HDi* symlinks instead
> 
DEVPATH=="/devices/pci0000:00/0000:00:1f.2/ata1/
host0/target0:0:0/0:0:0:0/block/sd*",
> ENV{ID_TYPE}=="disk", SYMLINK+="HDia%n"
> 
DEVPATH=="/devices/pci0000:00/0000:00:1f.2/ata2/
host1/target1:0:0/1:0:0:0/block/sd*",
> ENV{ID_TYPE}=="disk", SYMLINK+="HDib%n"
> 
DEVPATH=="/devices/pci0000:00/0000:00:1f.2/ata3/
host2/target2:0:0/2:0:0:0/block/sd*",
> ENV{ID_TYPE}=="disk", SYMLINK+="HDie%n"
> 
DEVPATH=="/devices/pci0000:00/0000:00:1f.2/ata4/
host3/target3:0:0/3:0:0:0/block/sd*",
> ENV{ID_TYPE}=="disk", SYMLINK+="HDif%n"
> 
DEVPATH=="/devices/pci0000:00/0000:00:1f.2/ata5/
host4/target4:0:0/4:0:0:0/block/sd*",
> ENV{ID_TYPE}=="disk", SYMLINK+="HDic%n"
> 
DEVPATH=="/devices/pci0000:00/0000:00:1f.2/ata6/
host5/target5:0:0/5:0:0:0/block/sd*",
> ENV{ID_TYPE}=="disk", SYMLINK+="HDid%n"
> 
> They create the symlinks I was wanting and 
which do indeed track the SATA cables regardless 
of the order the
> drives are plugged
> 
> $ ls -l /dev/H*
> lrwxrwxrwx 1 root root 3 Jul 27 13:38 
/dev/HDia -> sda
> lrwxrwxrwx 1 root root 4 Jul 27 13:38 
/dev/HDia1 -> sda1
> lrwxrwxrwx 1 root root 4 Jul 27 13:38 
/dev/HDia2 -> sda2
> lrwxrwxrwx 1 root root 3 Jul 27 13:38 
/dev/HDib -> sdb
> lrwxrwxrwx 1 root root 4 Jul 27 13:38 
/dev/HDib1 -> sdb1
> lrwxrwxrwx 1 root root 3 Jul 27 13:38 
/dev/HDic -> sdc
> lrwxrwxrwx 1 root root 4 Jul 27 13:38 
/dev/HDic1 -> sdc1
> lrwxrwxrwx 1 root root 4 Jul 27 13:38 
/dev/HDic2 -> sdc2
> lrwxrwxrwx 1 root root 4 Jul 27 13:38 
/dev/HDic5 -> sdc5
> 
> However, when I try to run udevadm - which 
does exist:
> 
> $ ls -l /sbin/udevadm
> lrwxrwxrwx 1 root root 16 Jul 27 10:55 
sbin/udevadm -> /usr/bin/udevadm
> 
> $ ls -l /usr/bin/udevadm
> -rwxr-xr-x 1 root root 253568 Jul 27 12:38 
usr/bin/udevadm
> 
> And appears to be a valid executable file
> 
> $ file udevadm
> udevadm: ELF 64-bit LSB executable, x86-64, 
version 1 (SYSV), dynamically linked (uses 
shared libs), for
> GNU/Linux 2.6.32, stripped
> 
> I get this message
> 
> $ ./udevadm
> udevadm: missing or unknown command

I believe this is just a simple case of udevadm 
requiring a command. Try udevadm monitor. 
Missing or unknown command is obviously not the 
clearest error message; it should really just 
print out standard usage.

Nimai

> 
> Missing dependency Somewhere maybe? Anyone 
have a clue? Because I'm stuck.
> 
> Thanks, Steve
>