anyway to extract a version string from a non running vmlinuz ?

rcorkum · 12-02-2006, 10:55 PM

as I said in an earlier post i am getting kernelitis and need to do some labeling now i could start tossing and redoing but if there is a way to get the version out already would make life easier and quicker (p233)

or the uncompressed vmlinux even.

thanks

gnashley · 12-03-2006, 03:23 AM

grep reads binary files so you can get it that way. at least in a round-about fashion:

grep "2.4.33" ./vmlinuz
returns true

In other words you'd have to write a script which would loop through the possible version numbers until it finds a match. Not very dependable...

archtoad6 · 12-07-2006, 01:46 PM

You could improve the reliability & possibly the speed of your script if you can determine the area of the vmlinu[z|x] the the string is located in, then use dd to limit your examination to that range of bytes:

Code:

F=<target_file>
M=<irrelevant_leading_bytes>
N=<interesting_bytes>
V=<list_of_version_strings>
X=$(dd bs=1 count=$N skip=$M if=$F)
for v in $V 
do 
   grep $v $F
done

also using fgrep may be faster. Sorry I'm on the road on <barf>an XP</barf> machine & cannot test my suggested code. caveat emptor

gnashley · 12-08-2006, 01:57 AM

Yeah, at first I thought of the 'magic' bytes that rdev reads/modifies and that the version string might be readable in a similar way.
I think there's no problem with speed using grep -it returns an answer right away. But having to loop through every possible version number could take a very long time. grep returns no location info -the kernel is a single long line of code I guess.
The version info is probably in a specific spot, though as you suggest -if we could just find out where then dd would be the way to get it.
Frankly, I think the exercise is mostly useless. The OP is obviously a newbie and if he really wants to know which kernel he's running, should install a known version and label it anyway he likes. Even if we get the version number, that still tells us very little about the kernel. I can see the utility of something like this though: if the kernel would print out a copy of it's config file -like the way busybox does. That way you could duplicate the kernel if needed.
I don't mean to be unhelpful -I gave the only solution I could think of since no one had answered the post. Some sort of loop using dd/seek should be able to find the location of the bits in question, then it would be fairly simple to query any given kernel.

kodon · 12-08-2006, 09:54 AM

its location doesn't seem to be nailed down

xflow7 · 12-08-2006, 10:39 AM

Why iterate through every possible kernel version? Couldn't you use a regular expression as the pattern for grep. Something like:

Code:

grep -e "2\.[46]\.[0-9]*" ./vmlinuz

if you knew that it could only be a 2.4 or 2.6 kernel. (apologies if I messed up the syntax, i can't test it at the moment)

You'd want to check that grep returned a single value to protect against there happening to be some other string in the image that would match a valid kernel version number but that's an issue even if you iterate through.

xflow7 · 12-08-2006, 12:12 PM

Oh just tried my suggestion and now I understand. grep won't return the actual match from a binary file, just whether or not it matches. Not such a hot idea after all, I guess.

kodon · 12-08-2006, 01:36 PM

decent idea

just use sed instead

rcorkum · 12-08-2006, 02:33 PM

Quote:

Originally Posted by gnashley

Yeah, at first I thought of the 'magic' bytes that rdev reads/modifies and that the version string might be readable in a similar way.
I think there's no problem with speed using grep -it returns an answer right away. But having to loop through every possible version number could take a very long time. grep returns no location info -the kernel is a single long line of code I guess.
The version info is probably in a specific spot, though as you suggest -if we could just find out where then dd would be the way to get it.
Frankly, I think the exercise is mostly useless. The OP is obviously a newbie and if he really wants to know which kernel he's running, should install a known version and label it anyway he likes. Even if we get the version number, that still tells us very little about the kernel. I can see the utility of something like this though: if the kernel would print out a copy of it's config file -like the way busybox does. That way you could duplicate the kernel if needed.
I don't mean to be unhelpful -I gave the only solution I could think of since no one had answered the post. Some sort of loop using dd/seek should be able to find the location of the bits in question, then it would be fairly simple to query any given kernel.

oh I appreciated the help I really did, thats what I did load each one I was questioning rebooted and unamed it and then renamed the system.map and kernel to match what it was and repeated till done. just been intrigued and following the responses.

Rob