[lfs-dev] udev rule problem

Bruce Dubbs bruce.dubbs at gmail.com
Fri Oct 27 10:33:10 PDT 2017

I ran into an interesting problem the other day.  udev was not creating a 
/dev/dvd -> /dev/sr0 symlink.

I finally traced it down to a udev rule that we had in the book since 2014.

# Fail the uevent if the autogenerated rules cannot be saved
ENV{ID_CDROM}=="?*", PROGRAM="/bin/grep -c ' / [^[:space:]]* rw' 
/proc/mounts", \
   RESULT!="2", RUN+="/bin/false", GOTO="cd_aliases_generator_end"

This was checking for a writable root filesystem.  Upon checking, this was 
returning a RESULT=1 and incorrectly skipping the following command which 
generated the symlinks.

The change was to look for RESULT!="1".

The udev rules we use came from Debian and we have not changed them since 
we initially installed them in April 2014.

I have updated the book to reflect this change.

   -- Bruce

P.S.  Actually now that I am documenting this, I don't think this check is 
really needed at all as the writing is done to /dev which is writable when 
first mounted in the very first boot script.

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