On 01/27/15 18:38, Alexander Holler wrote:
Am 27.01.2015 um 18:24 schrieb Steven Rostedt:
For most people a message in dmesg is not very useful. What you are
asking for
is to print a characteristic of a device. Something that someone might
want to
check much later in boot, where, as Boris stated, the dmesg could have
been
flushed (by systemd, which loves to write stuff to the kernel
buffers), and
there's no way to find out this information. The print message is long
gone.
Having a static location like sysfs is the proper place, because user
space
tools can always access it.
Is this something a tool would like to find out? If so, parsing dmesg
is not
the way to go. Looking it up in sysfs is.
Oh, systemd.
Anyway, I like(d) Linux because it didn't had a splash screen and used
to spit out all types of information on the screen where it could be
easily seen or found (in contrast other OS which try to hide all
technical details from users).
What ends up in kernel log is still a fraction of what is going on in
the kernel.
Of course, times are changing, including the amount of stuff printed on
screen. But I still find it much much easier to grep on the output of
dmesg than to search through thousands files in sysfs. Even if that can
be done with grep too (kind of). But it's much more complicated because
grep doesn't connect the file name with the content, so you need more
complicated stuff to combine both in order to search for and find
something in sysfs.
Ever used rgrep or grep -R. Anyway, if this is you use-case what about
the gazillion other pieces of info in the kernel. When moving in that
direction you can be sure dmesg will flush out.
Regards,
Arend
Regards,
Alexander Holler
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