On 02/16/2016 09:19 PM, Mike Wright wrote:
On 02/16/2016 08:15 AM, Chris Murphy wrote:
At the GRUB menu, type
pager=1 set
Look for variable 'prefix=' this will be drive, partition, and path, to the GRUB directory where its cfg and modules are found.
All right Chris!
While at the boot prompt I have no access to anything and had forgotten the "pager=1" bit so after getting into grub> it was hit or miss with huge text overflowing the screen. By habit I typed ls and don't know if what it did was what I expected but near the bottom of the screen was the prefix= line. Ahhh, serendipity.
I copied, with pencil and paper, the 102 character string, cursing the entire time the genius behind this madness, and rebooted.
A portion of that string, reformatted without slashes and hyphens, was located in one of /dev/disk/by-id's 107 entries and which turned out to be a sym-link to dm-16. dm-16 was claimed by a sym-link in /dev/mapper.
(Editors comment: this crap could only have been created by somebody with a cast of thousands and an unlimited budget and would have gotten an "F" at the Oscars.)
And there was a recognizable quatrain of stanzas minus any commenting other than the title. After editing and changing the module lines to refer to the current kernel (when booting Xen kernels and initrds are modules) I rebooted and... WTF? the original unmodified boot page.
So apparently grub.cfg is ?compiled? into some other secret location know only to the bootloader. I have the sinking feeling I have to run some grub2 magic spell to get the modified boot file into wherever it goes but am loathe to try anything. The reason I have a stripped down grub.cfg is because the last one generated for me was pushing 200K and the boot lines in each stanza had, so help me, nineteen swap files included in each one.
Now the question:
Is there a command that will take my simplified grub.cfg and install it without modifying it in any way and leave me with a bootable system? (please please please say yes).
I've never used it, but I suspect grub-menulst2cfg may do what you want. It claims to "Convert a configuration file from GRUB 0.xx to GRUB 2.xx format". If you're going to continue to tinker in this way, you really have to read up on grub2:
http://www.gnu.org/software/grub/manual/grub.html
I agree it's convoluted and confusing and I'm not a fan (just like I'm not a fan of systemd or journald), but that's what you're stuck with.
Most of the config info you may need to change is in /etc/default/grub. The scripts that generate the menu entries are in /etc/grub.d (particularly 10_linux and possibly 40_custom). The final config created by grub2-mkconfig generally ends up in /boot/grub2/grub.cfg.
Dunno if that helps, but... ---------------------------------------------------------------------- - Rick Stevens, Systems Engineer, AllDigital ricks@alldigital.com - - AIM/Skype: therps2 ICQ: 226437340 Yahoo: origrps2 - - - - I haven't lost my mind. It's backed up on tape somewhere, but - - probably not recoverable. - ----------------------------------------------------------------------