How do I drop to shell from rescue CD???
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From: Bill Waddington on 22 May 2010 11:04 On 22 May 2010 13:30:12 GMT, "Chris F.A. Johnson" <cfajohnson(a)gmail.com> wrote: >On 2010-05-21, Robert Riches wrote: >> On 2010-05-21, Ohhhh maaan <nobodyhere(a)example.com> wrote: >... >>> I had attempted that previously, didn't work from rescue disk. In the >>> end, it was a bad image on the (CD) disk. >> >> Wouldn't that be "disc"? > > That depends on where you live. It's "disk" at my house, wherever I happen to live. I guess it's "disc" most everywhere else. Hell, it's still "multiplexer" at my house, and "multiplexor" everywhere else. Grrr. I'm not sure whether to blame main-stream news, sports announcers, or pointy-haired bosses for the corrosion of the language. Don't get me started on "begs the question" and "quantum leap" - or the excessive use of quotation marks. Bill -- William D Waddington william.waddington(a)beezmo.com "Even bugs...are unexpected signposts on the long road of creativity..." - Ken Burtch
From: Denis McMahon on 22 May 2010 13:43 On 19/05/10 04:44, Keith Keller wrote: > ["Followup-To:" header set to comp.os.linux.misc.] > > On 2010-05-19, Ohhhh maaan <nobodyhere(a)example.com> wrote: >> >> I've used Linux years ago and I think I recall you could just type linux >> single or linux emergency at the boot CD, but nothing works with this >> new CentOS 5.x rescue CD. I'm stuck at "boot:" and nothing I try just >> drops/boots me into a shell prompt. Please, help! :) > > Close: it's linux rescue, not emergency: > > http://www.centos.org/docs/5/html/Installation_Guide-en-US/s1-rescuemode-boot.html > > But I believe the onscreen text tells you to hit F5 for help and > other boot options, so you should look for that next time. See e.g. I think his problem may be terminology? Looking at the centos rescue cd instructions, the "install image" it's looking for is the bootable rescue system, it's not going to reinstall linux automatically from the "rescue image". If it's a correctly configured bootable CD, then he should be able to use "Local-CD" as the location of the installabalke system. By installable, it really means "bootable". In other words, when you boot rescue mode, the bootloader needs to be told which kernel to boot, so you have to tell it to use the one on the CD. The term it uses is "install image" .... but it means where is the system you want me to boot. So, start off the rescue cd, tell it to boot "local CD" When it prompts about mounting the HDD, let it mount it r/w under /mnt/sysimage (continue) Now, hopefully, the HDD /boot/grub is at: /mnt/sysimage/boot/grub whereas /boot/grub is the /boot/grub dir on the CD rom which is probably ro! If you need to edit eg /boot/grub/grub.conf or /boot/grub/menu.lst on the HDD, or just mv a backup to overwrite the current version, you need to cd / mnt/sysimage/boot/grub after getting the prompt. You shouldn't need to use ctrl-alt-f1 / ctrl-alt-f2 as long as you can apply your fix from a single shell, as after it mounts the old filesystem it should drop to a console. Not sure if sed is available at that point, but it seems an editor called joe is. I think your problem is that the terminology is confusing you and you're giving up before the boot CD actually does just what you want it to. In summary: Boot from the CD, use the rescue option, tell it to use itself for the installable image, continue when it asks if you want to mount disks, then when it drops you to a prompt cd to /mnt/sysimage/boot/grub and see if you can fix whatever is broken in there. Rgds Denis McMahon
From: Keith Keller on 22 May 2010 14:03 On 2010-05-22, Denis McMahon <denis.m.f.mcmahon(a)googlemail.co.uk> wrote: > > I think his problem may be terminology? Well, the OP already posted that the problem was a bad CD. So... > You shouldn't need to use ctrl-alt-f1 / ctrl-alt-f2 as long as you can > apply your fix from a single shell, as after it mounts the old > filesystem it should drop to a console. ....switching to another console might enable him to see error messages that aren't displayed during the rescue configuration process. (IIRC one of the consoles actually logs syslog-like messages.) In any case it's a good thing to remember when confronted with a seemingly stuck process on the screen. --keith -- kkeller-usenet(a)wombat.san-francisco.ca.us (try just my userid to email me) AOLSFAQ=http://www.therockgarden.ca/aolsfaq.txt see X- headers for PGP signature information
From: Denis McMahon on 24 May 2010 23:04 On 22/05/10 19:03, Keith Keller wrote: > On 2010-05-22, Denis McMahon <denis.m.f.mcmahon(a)googlemail.co.uk> wrote: >> >> I think his problem may be terminology? > > Well, the OP already posted that the problem was a bad CD. So... Didn't see that, saw that his issue was it was asking for install file locations after booting the CD, but that's part of the normal boot, and you can tell it that the files are on the cd. I think the reason he thinks the CD is bad is because he doesn't understand the question it's asking, and is interpreting it as asking for the location of install media when in fact it's asking for the location of a boot image. I thought he might have been confused by the terminology, when it asks for a "location of install files" during the emergency boot process I think it means "what media is the bootimage for the rescue kernel located on", which presumably is the cd. I think at that point he should tell it local-cd and carry on booting, then it should drop to a shell at some point, and then he can use the joe editor to edit the file as long as he goes to the right place. At least, that's my interpretation of reading through an online explanation of the centos recovery CD boot sequence. >> You shouldn't need to use ctrl-alt-f1 / ctrl-alt-f2 as long as you can >> apply your fix from a single shell, as after it mounts the old >> filesystem it should drop to a console. > > ...switching to another console might enable him to see error messages > that aren't displayed during the rescue configuration process. (IIRC > one of the consoles actually logs syslog-like messages.) In any case > it's a good thing to remember when confronted with a seemingly stuck > process on the screen. Yes, but as I understand it the switching keycode isn't passed through his remote kvm link. Rgds Denis McMahon
From: Ohhhh maaan on 27 May 2010 17:39
Denis McMahon wrote: .... > > I think the reason he thinks the CD is bad is because he doesn't > understand the question it's asking, and is interpreting it as asking > for the location of install media when in fact it's asking for the > location of a boot image. I understood what it was asking and doing, I just was asking about bypassing all of the checks for the install images or rescue images, depending on which I could try, because the kernel itself (from the CD) would boot fine, but it then forced it to seek the rescue image. It was a bad CD media, because it took several times to select the rescue image before it said it could find it on the CD (same CD, doing nothing but re-trying). I found this out when I instead selected the rescue image (not sysimage path) from the hard drive (which it didn't exist there, of course) and then went back to tell it to check the CD (only then could it be seen as existing on the CD). > I thought he might have been confused by the terminology, when it asks > for a "location of install files" during the emergency boot process I > think it means "what media is the bootimage for the rescue kernel > located on", which presumably is the cd. That's just it, it looked like it wanted more than the CD's rescue image, because after all, it appeared to be working without issue (in the end, it wasn't, however). > I think at that point he should tell it local-cd and carry on booting, > then it should drop to a shell at some point, and then he can use the > joe editor to edit the file as long as he goes to the right place. Exactly, which was what I was able to do with the same version/rescue media, but a different media disk. That's what was driving me crazy, because the CD seemed fine before I found this out. |