General :: Trying To Understand Where Bootloaders Are Installed
Apr 28, 2011
In the beginning there is MBR. MBR looks for the active partition and tranfers control to the VBR of the active partition. MBR is where grub may be installed. which allows the user to choose an OS(a VBR) I am not sure what the program in the VBR does,but it manages to loads the OS. What am I trying to do: Backup. I ma tired of losign my partitions my bootloaders. I want to backup them all! partitions/MBR /VBR everything short of creating an disk image.
My questions:
1. say the ubuntu partition is formatted, will grub still load? if not is there a bootloader that would?am I making sense? i hope so...
2. what exactly does the VBR contain ?
2. How do I go about backing up? The mbr and the partiton table are backed up with a simple dd command. Then what else needs to be backed ? VBR's of every partition?
Just installed Ubuntu 10.10 as a dual boot on my Windows 7 Ultimate machine, and it's working quite nicely.However, when booting windows, I have to go through a second, extra bootloader to get there.The first is less pretty, and has lots of options (grubv1.98+ 20100804- 5ubuntu3), the second is prettier and has just 2 boot options, Windows and Ubuntu. It's not crippling, but it is annoying to have to go through two, and I'd like to get rid of one.I think I know why this has happened; I installed Ubuntu from Windows using the wubi installation program, then decided that wasn't what I really wanted to do (I'd cleaned out an entire hdd partition specifically for Linux, so having it embedded in a Windows file seemed unnecessarily complex). I deleted the install manually - NOT with the windows uninstaller, stupidly, as I didn't realise that was possible. Presumably, this did not remove the bootloader. I then installed ubuntu from CD on my empty partition.I haven't tinkered with it too much, as it works currently and I don't want to risk make things worse by not knowing what I'm doing. Firstly, has this happened for the reason I think? Is there a way to delete just the second, presumably obsolete bootloader without damaging the first? I was considering doing a quick reinstall from Windows to allow me to do a proper uninstall, but I really don't want to risk ending up with 3 bootloaders!The obvious, long approach is to start fresh by letting Windows rewrite the MBR with a rescue disk, and then install ubuntu just once - is this the best option? Would this even work?
Modern systems seem to be EFI based, and while there's a specific version of lilo that works with it, i can't seem to find any mention of a efi varient of grub (edit - on modern debian derivative systems there's grub-efi. Most references to it seem to be about various bugs in/for it tho) . In general, how well is EFI supported on linux?In addition, apparently windows 7 uses EFI to enable faster boot - 12 seconds or so with some systems. While a properly tweaked linux system could probably come close, are there any enhancements to the linux booting procedure that take advantage of EFI?
I have taken putty session of a server from two separate machines namely HOST1(3 sessions) and HOST2(1 Session) . However w command says there are 5 users
Code: # w 09:29:36 up 34 days, 15:48, 5 users, load average: 0.62, 4.33, 8.16 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT root pts/17 HOST1 09:18 4:26 0.01s 0.01s -bash root pts/18 HOST1 09:27 1:21 0.00s 0.00s -bash root pts/21 HOST2 09:29 0.00s 0.00s 0.00s w root pts/20 HOST1 09:29 1:39 0.00s 0.00s -bash
python can get anylink or any tutorials which is having few basic eg. and could help as a guide too. bcaz whatever now i have like "byte of python" which i feel difficult bcaz it lack in having eg. for modules of xml.so please help me by providing any better options
I am here looking for some abstract and easy to understand resource for "Exokerel" CONCEPT of Computer Operating Systems.[URL] seems some what more complex then expected [URL]
I am a linux newbie (more so with using RedHat). I am trying to use yum to install packages, but have never really able to get this thing right. I want to install libXp-devel package. However, running yum install libXp-devel doesn't work.
When I downloaded the rpm for libXp-devel and tried to run yum install libXp-devel-1.0.0-8.1.el5.x86_64.rpm, I get the following:
Code:
Resolving Dependencies --> Running transaction check ---> Package libXp-devel.x86_64 0:1.0.0-8.1.el5 set to be updated --> Processing Dependency: libXp = 1.0.0-8.1.el5 for package: libXp-devel --> Processing Dependency: libXau-devel for package: libXp-devel
I am anticipating that someone could give more further information about that, not only simple explanations. How to understand User Time, sys time, wait time, idle time of CPU
I'm in way over my head and have absolutely no idea what I am doing.I set up a lamp server earlier today on ubuntu 10.10 and I'm trying to upload files to wordpress which I installed at local host using vsftpd. I am so lost.Something about this entire process has not clicked in my head;
This problem is occurring on Red Hat EL 5 WS. However, I have two CentOS 5 systems, with similar configuration to RH EL 5, where this problem does not occur.
I am getting this error:
Can't exec "sendmail": No such file or directory at ./0logwatch line 1018, <TESTFILE> line 1. Can't execute sendmail -t: No such file or directory
Well I get my other 2 questions answered , I have one last question that has been buggy me.Anyone know why windows use so many files just to keep the OS going and so bloated? The under line of files of windows is messy and loads self every where and very bloated with windows and windows vista and windows 7 very much so.I'm not sure if Linux /Mac OS X is like this or not .
I know windows needs to support alot more software and hardwar but is that not where drivers come in for the hardware.And programmers need to write the software for windows or Linux / Mac OS X.
In my book, this is an example of a recursive algorithm:
var reverseArray = function(x,indx,str) { return indx == 0 ? str : reverseArray(x,--indx,(str+= " " + x[indx])) ;; } var arr = new Array('apple','orange','peach','lime'); var str = reverseArray(arr,arr.length,""); alert(str) ;
I'm trying to understand it, I'm stuck at the (str+= " " + x[indx])) part - that part of the function definition expects an ARGUMENT, am I right? What's being passed to it is a bit of PROGRAM, the str+= stuff. So - how is it working?
a lot of log file store in location /var/log/ but how to understand what the meaning in side the log file recorded down? how to find out the problem from the log file?
I have just started using Valgrind,which really is great. Most of the reported errors look kinda weird, though I can't really understand what's going on here, for example:
==00:00:02:52.033 7754== Invalid read of size 4 ==00:00:02:52.033 7754== at 0x80B0987: MyCls::MyPrintf(long, char*, ...) (MyCls.cpp:270) ... ==00:00:02:52.033 7754== Address 0x47a5ee8 is 0 bytes after a block of size 296 alloc'd ... ==00:00:02:52.033 7754== by 0x809A6C1: ClsMain::taskRun(int, char**) (ClsMain.cpp:177) ==00:00:02:52.033 7754== by 0x816CFE8: main (main-C.cpp:2060)
==7754== ---- Attach to debugger ? --- [Return/N/n/Y/y/C/c] ---- Y ==00:00:02:57.410 7754== starting debugger with cmd: /usr/bin/gdb -nw /proc/7765/fd/1014 7765 GNU gdb Red Hat Linux (6.5-25.el5rh) Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i386-redhat-linux-gnu"...Using host libthread_db library "/lib/libthread_db.so.1".
Attaching to program: /proc/7765/fd/1014, process 7765 MyCls::MyPrintf (this=0x47a5dc0, iPrm=3, sMsg=0x6974320 "blablabla"...) at MyCls.cpp:270 270 cout<<endl<<"m_FilePtr="<<hex<<m_FilePtr<<dec<<endl;
Basically, Valgrind reported the "Invalid Read" error at line 270 of file MyCls.cpp, which is simply a cout of the m_FilePtr variable, which is a member variable of the MyCls class. It's a FILE* variable I use to write repeatedly on a text file. The address reported (0x47a5ee8) is 296 bytes after the "this" pointer (0x47a5dc0),as Valgrind correctly tells me but I honestly don't understand that. And of course, I need to read that variable, not only for the cout (indeed,the error is reported at every reading attempt). Besides, the application doesn't crash, but still I would like to understand if I really have to worry about this "error".
i really confuse now..many people gave recommendation for many book.i have little experience on networking what is the best book for understand Linux Networking from Scratch..
I have got a program using semctl(). I cant understand the value returned by semctl using GETPID option and its difference with the actual pid obtined by getpid()as in the following code:
Code:
int semid,retval; semid=semget(0*20,1,0666 | IPC_CREAT); retval = semctl(semid,0,GETPID,0);
I am getting shift/reduce and reduce/reduce conflict in my yacc grammar code. yacc generates (i.e yacc -d -v parser.y) its grammar and state information in the parser.output file.
How can i interpret the below information and understand which grammar state is conflicting with other grammar state? Please help me to understand.
State 159 conflicts: 1 shift/reduce State 1863 conflicts: 1 shift/reduce State 1865 conflicts: 1 shift/reduce State 1960 conflicts: 1 shift/reduce
I have be unable to access my bt homehub from another (external) ip address recently. I didtrace route to see what is happening to the connection and got the following.
It bounces around as it gets out my offices network and then seems to get to BT's servers and then I get stars. what that means?
1 - 8 bouncing round office network: 9 linx3.ukcore.bt.net (195.66.224.11) 19.405 ms 19.424 ms 19.381 ms 10 core2-pos0-1-5-0.ilford.ukcore.bt.net (62.6.201.121) 20.774 ms 21.099 ms 19.986 ms
I am trying to understand a large amount of allocated memory that seems not to be accounted for on my system.I'll say up front that I am discussing memory usage without cache and buffers, 'cause I know that misunderstanding comes up a lot.I am in a KDE 4.3 desktop (Kubuntu 9.10), using a number of java apps like Eclipse that tend to eat up a lot of memory.after a few days, even if I quit most apps, 1 gb of ram remains allocated (out of 2 gb).this appeared excessive, and I took the time to add up all values of the RES column in htop (for all users).the result was about 1/2 gb.am I trying to match the wrong values?or could some memory be allocated and not show up in the process list?this is the output of free
Code: total used free shared buffers cached Mem: 2055456 1940264 115192 0 123864 702900
I ran a firmware test, after I discovered a bad memory stick on a 1 gb stick. Replaced my memory stick and just for grins ran a firmware test and I don't understand this:[Fail] Failed to locate HPET base [Fail] OS/2 memory hole test-The memory map has a memory hole between 15mb & 16mb.
Re-ran MEMTEST just to make sure my new memory was fine, no errors.My Linux OS appears to be running slower on boot-up than normal, What documentation there is on the internet on HPET is over my head.I ran SMART on the both drives. They were good. So I am a little stumpted.