Tuesday, December 4. 2007
When a system is too damaged to permit booting from the hard disk drive, it's necessary to boot from another medium. The Fedora installation discs support a "Rescue mode" in which the system is booted from the CD and the hard disk partitions are optionally mounted for access.
To access this mode, boot from your Fedora install media and select "Rescue installed system" from the boot menu using the arrow keys and Enter or by pressing the R key (if you need to edit the boot options first -- to disable ACPI, for example -- navigate to the Rescue option with the arrow keys and press Tab).
The kerenel will boot from CD and the system will prompt you to select a keyboard style and language from scrollable lists of options. You will then be given the opportunity to enable the network interfaces on the system, either by entering the IP information or by using DHCP.
The system will then present a dialog stating that the rescue environment is about to find and mount the filesystems from your hard disk Fedora installation, and asks if you wish to continue. This is a critical question: if your filesystems are intact and you wish to access the data that is in them, you can select Continue, the default option. If you are concerned about the state of your filesystems and want to ensure that they will not be altered, but still want to access them, select Read-Only. If your filesystems are damaged, you have multiple Fedora installations, or you wish to perform an operation such as reducing the size of the root filesystem, choose Skip. After some additional messages, you will be presented with a root shell prompt.
If you have elected to continue with read/write mounting of your filesystems, all of the files from your Fedora installation should be available under /mnt/sysimage -- so the normal /etc/passwd file will be available at /mnt/sysimage/etc/passwd.
Although regular Fedora commands and utilities are available in rescue mode, most of them will not work because of the altered paths. You can work around this issue by temporarily changing the root directory using the chroot command:
However, you need to be aware that files within the mounted Fedora filesystems will not have been updated during the rescue mode boot process, including /etc/mtab and /var/log/messages. You can compensate for this by some degree by getting the information from other places (such as dmesg for kernel messages and /proc/mounts for mount information).
If you have been forced to use rescue mode because your system's Grub bootloader code has become damaged or has been overwritten by another bootloader, you can reinstall the Grub bootloader in rescue mode:
You can also use rescue mode to set the root password, create alternate superuser accounts, or change or remove a boot password. Whether these are important recovery operations or a type of attack depends only on the context in which they are performed. You can slow down such an attack by configuring the system BIOS to boot only from the hard disk and installing a BIOS password, but that can be reset using a motherboard jumper in most cases. The moral of the story: if you don't have physical security, you don't have system security.
When you are finished using rescue mode, type exit or press Ctrl-D twice. The system will then reboot.
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I was stuck with exactly the same problem and the solution worked all right with me. Thanks for posting this info.
Hey, worked great. Thanks a lot.
#2 GB on 2008-03-09 21:56
#4 James on 2008-06-30 21:21
I had dual system windows xp on first primary partition ntfs and fedora linux on secondary primary partition ext3.
My windows xp got currupt and i reinstalled it. I override the Grub menu. Now windows xp directly starts up when i boot up my system. Grub is not showing any where. Anybody knows how to resolve this issue.
Thanks, take care.
XP would have reinstalled the boot sector. Install the Grub boot sector again (using the instructions here) and you should be good.
Thanks for this article (and this excellent website!). I found this near the top of a Google search, and it allowed me to restart my computer after a Fedora 9 kernel update left my system unbootable. Good thing I had another working computer! Total time, after downloading and burning the rescue CD-- less than a minute.
OMG YOU SAVED MY BUT THANKS
#7 peter on 2008-08-19 07:23
Amazing post pal. I was in the same problem...if you don´t post this I was near to reinstall everything.
Thanks a lot, great job, you did a clear and detailed explanation.
Wow, thank you very much Chris - worked perfectly !
#9 Dana Dane on 2008-10-21 09:48
Thank You, a fedora 9 update left my computer unbootable! All that would display is "grub ", and your guide saved my bacon.
#10 Eric Anderson on 2008-10-29 00:13
*Brilliant*; all's well in paradise once again!
#11 Gemma Calvert on 2008-10-30 21:58
hey.... it works .. thanks alot.. can some body tell me whether there is any other way to get fedora everything spin... except throughjigdo ???????
plz mail me the link
Well I must be the first person that it dosn't work for is there anything els I can do or is my bios or mother board just shot?
Big thanks for this article! Worked smoothly.
#14 voj-tech on 2008-12-04 07:39
Chris - thanks for the post. I had problems with new Fedora Core 10. Went back to basics and followed your steps to rescue my previous install.
Thanks for this information. I had an FC10 update trash my GRUB loader and this saved the day, worked perfectly.
Thanks very much,
#16 Doug L on 2008-12-27 17:26
Briliant, simple, and effective. Thanks a million!!
#17 Mik Zic on 2009-01-14 14:29
Thanks a lot for your tips and trik, cos, it works.....
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