Bootloader issues: what happens before the operating system itself starts.

learn more… | top users | synonyms

42
votes
8answers
28k views

SSH to decrypt encrypted LVM during headless server boot?

When I installed Ubuntu 10.04 and, now, 10.10, I was offered the option of enabling "encrypted LVM" for my hard drive. After choosing that option, I am prompted for my password during boot to decrypt ...
38
votes
3answers
110k views

How can I make a script in /etc/init.d start at boot?

I think I read something a while back about this, but I can't remember how it's done. Essentially, I have a service in /etc/init.d which I'd like to start automatically at boot time. I remember it ...
30
votes
5answers
32k views

Why does Linux allow ‘init=/bin/bash’?

I recently found out that if I edit GRUB before booting and I add rw init=/bin/bash I end up with a root shell. Being in a condition that I want to understand everything I would like to know why this ...
26
votes
2answers
3k views

When do I need to specify add_efi_memmap as kernel argument in UEFI/EFI boot?

I am reading some tutorials how to EFI stub (efistub) load the Linux kernel. These instructions often use kernel boot parameter add_efi_memmap. The intended hardware is Intel x64 having 8GB of RAM. My ...
21
votes
7answers
1k views

Why do most distributions chain UEFI and grub?

Most distributions install a additional boot loader on an UEFI system. UEFI itself is a boot loader, it offers a menu to select different operating systems or individual kernels. Furthermore, the UEFI ...
18
votes
9answers
86k views

How to boot Linux to command-line mode instead of GUI?

I am using 32-bit Red Hat Linux in my VM. I want to boot it to command-line mode, not to GUI mode. I know that from there I can switch to GUI mode using startx command. How do I switch back to command-...
18
votes
5answers
29k views

Stop program running at startup in Linux

How do I stop a program running at startup in Linux. I want to remove some apps from startup to allow them to be managed by supervisord e.g apache2
17
votes
2answers
16k views

How to know if I'm booting using UEFI

I was searching, but didn't found an obvious way to know if GRUB is using UEFI in the system boot, or the BIOS compatibility mode or a full fledged BIOS. Only Windows methods. Is there something in ...
17
votes
4answers
29k views

How do I boot from a liveusb using qemu-kvm?

I am trying to get qemu-kvm to boot from my live usb stick. Is this possible?
17
votes
5answers
31k views

What is the difference between LILO and GRUB?

I am running a web server under Debian and I currently have GRUB installed. Should I consider using LILO instead of GRUB? And what are the advantages of each?
17
votes
3answers
41k views

CentOS eth0 not starting

Why would my new CentOS Virtual Machine not start eth0 on startup? I have to start it manually every time. How can I fix this? Thanks.
17
votes
4answers
11k views

How can I avoid “Run fsck manually” messages while allowing experimenting with system time changes?

I'm working with a system where we want to allow users to play around with the date and time if they want, and where reboots may happen arbitrarily. This is fine, except for one thing: if there's a ...
17
votes
1answer
1k views

Rebooting without shutting off?

I have been using Linux Mint Debian with Debian unstable and noticed that when I press restart, instead of going all the way back to the BIOS, then grub, then booting up, I seem to be shutting down ...
15
votes
2answers
15k views

Why can't I specify my root fs with a UUID?

My system boots OK with this in my GRUB 2 config: linux /bzImage root=/dev/sda2 init=/usr/lib/systemd/systemd ro But if I replace /dev/sda2 with the corresponding UUID: linux /bzImage root=...
15
votes
1answer
13k views

How can I test the RAM for data corruption on an ARM-based system?

I have an embedded device. It is ARM based, with Linux 2.6.31 and has 256 MB RAM. I wanted to get some ideas/tips on what is the most effective way to test the device RAM for data corruptions. Is ...
15
votes
2answers
7k views

What is needed for a minimal systemd boot to launch getty on a virtual console?

For SysV init, I need /etc/inittab respawning getty entries, the /sbin/init binary, the binaries and shared libraries for the shell, login, the getty, the PAM/security/shadow stuff, and a few device ...
15
votes
3answers
30k views

What is the “Bootable flag” option when installing a distro?

Is the "bootable flag" needed in today's distributions? If not, then Why is it still in the installers? What is it exactly?
14
votes
4answers
3k views

Is there a way to auto turn-on Ubuntu?

Like a command line or a small piece of software I know that there are many ways to auto-shutdown, but I'm concerned about auto-turn-on.
14
votes
4answers
4k views

discribe in details tha boot process of any linux system

I am preparing a document in detail showing light on the boot sequence of Linux right from pressing of Power-on button the host to the login prompt appearance. It would be great if we could combine ...
13
votes
1answer
2k views

mistakenly deleted /boot folder and rebooted

I mistakenly deleted the /boot folder from my filesystem, rebooted, and all I get now is this: error: file '/boot/grub/i368-pc/linux.mod' not found. grub rescue>
13
votes
4answers
12k views

How to get rid of the “scanning for btrfs file systems” at start-up?

After upgrading from Ubuntu 12.04 to Ubuntu 12.10, I get a message "scanning for btrfs file systems" at starting-up. I don't have any BTRFS filesystem. It delays the booting for about 15 seconds. How ...
12
votes
3answers
3k views

How should I configure grub for booting linux kernel from a USB hard drive?

I have a laptop hard drive in an external enclosure which I use as a large pendrive. For an added twist, I have installed Linux on it, so I can boot any machine with my distribution of choice (e.g. ...
11
votes
2answers
20k views

Why do iptables rules disappear when restarting my Debian system?

I add this rule: sudo iptables -t nat -A OUTPUT -d a.b.c.d -p tcp \ --dport 1723 -j DNAT --to-destination a.b.c.d:10000 When restart computer rules are deleted. Why? What I can do to make ...
11
votes
2answers
12k views

Bash Script on Startup? (Linux)

Is there any way to make/run a bash script on reboot (like in Debian/Ubuntu for instance, since thats what my 2 boxes at home have) Also, any recommended guides for doing cron jobs? I'm completely ...
11
votes
2answers
606 views

Removing abstraction from Ubuntu boot process

I have been using Linux after almost 5 years and observed that boot process has been almost abstracted. I mean, not much is visible to the user what is going on behind the scenes (Due to splash ...
11
votes
1answer
16k views

Where do I find messages regarding last failed linux boot?

My linux boot fails often. I have removed quiet from my boot options so I can see whats going on. Basically after showing a bunch of [pass] messages, it hangs. It does not hang every time. Now I know ...
11
votes
1answer
14k views

How To create a FreeBSD 10 bootable USB?

Currently I am Using Linux Mint 17 and I want to dual boot FreeBSD and Linux Mint 17. How can I create Bootable USB for FreeBSD 10? I tried Unetbootin, Image writer and powerISO but it's not working....
11
votes
1answer
3k views

How is /etc/fstab accessed before root is mounted?

I was making some changes to /etc/fstab, when this chicken and egg question occurred to me - if /etc/fstab contains the instructions for mounting the file systems, including the root partition, then ...
11
votes
3answers
28k views

How to set global environment variables at boot through a script, and have them available for an application that runs before login?

I have a service that runs at boot, and in that service it calls a bash script in the background that exports some environment variables. The problem I'm having is that those environment variables ...
11
votes
2answers
104k views

How to fix boot into initramfs prompt and “mount: can't read '/etc/fstab': No such file or directory” and “No init found”?

Installing a new system using a GPT partitioned disk dedicated to a single partition, ext4 formatted, extlinux (version 4.05) as bootloader, Ubuntu Core version 13.10 amd64 as rootfs, and Ubuntu linux-...
11
votes
1answer
2k views

Why would a partition be in use by the system if it isn't mounted?

I've been migrating my system from btrfs to ext4 after running into performance issues with VMs. I have two hard drives in my laptop to work with. I've successfully moved my home partition, but the ...
10
votes
6answers
21k views

How does a kernel mount the root partition?

My question is with regards to booting a Linux system from a separate /boot partition. If most configuration files are located on a separate / partition, how does the kernel correctly mount it at boot ...
10
votes
3answers
12k views

boot partition is almost full in CentOS [duplicate]

I got a warning of my /boot partition is almost full(85%). What should I do? Can I remove one of the backup kernel? How to do it safely? My partition right now Filesystem 1K-blocks ...
10
votes
2answers
22k views

How to check on which drives grub2 has actually installed an MBR?

I'm on a Debian/Squeeze system (with a history going back to at least Woody) which was upgraded to grub2 as part of the Squeeze upgrade. All works well, but I'm about to mess with the disk ...
10
votes
2answers
11k views

Human readable dmesg time stamps on OpenWRT

The output of dmesg shows the number of second+milliseconds since the system start. [ 10.470000] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver [ 14.610000] device eth0 entered ...
10
votes
2answers
528 views

“Grep breaks, causing the boot process to hang forever”

Question within a question (from the Debian wiki): Should I use sid on my desktop? If you think you can handle a broken Debian system, sure. Do you know what to do if libpam0g breaks, ...
10
votes
1answer
7k views

Creating a bootable Linux installation USB without unetbootin

I want to install Scientific Linux from USB. I don't know why unetbootin doesn't work but I am not curious to find out: after all, I transferred to Linux from Windows to see and learn the underlying ...
10
votes
1answer
36k views

How to create bootable flash for “efi-shell”

Current Intel server chipsets include a built-in "efi-shell" which appears to basically be a simplified 'NIX with a command set suitable for manipulating some nifty UEFI boot options. It is also the ...
10
votes
5answers
33k views

Installed Centos 7 after Windows and can't boot into CentOS

I wanted to setup a dual boot for Windows 7 and CentOS 7 I had a Windows 7 machine with 500GB disk. I shrank the Windows partition to provide space for CentOS 7 (roughly 230GB). I created a USB ...
10
votes
1answer
12k views

What's the point of rootwait/rootdelay?

rootwait and rootdelay are used in situations when the filesystem is not immediately available, for example if it's detected asynchroneously or mounted via usb. The thing is, it should be obvious ...
10
votes
1answer
6k views

Load Linux bzImage in QEMU?

I compiled a Linux by doing make menuconfig then make and now I have compiled the most recent version of Linux. How can I load the kernel into QEMU?
9
votes
1answer
2k views

Relationship of keyboard layout and xmodmap

I'm using Xubuntu. Before login I can choose a keyboard layout. I'm using xmodmap for remapping some keys. I'm interested in two things: How the state of keyboard mapping changes (a) when I turn ...
9
votes
5answers
9k views

Is it possible to put root in LVM without using initrd?

I have just set up a Gentoo base system (which means I can boot and log in and do stuff with it now). My root partition is in an LVM2 virtual group (with a separated /boot partition). In order to boot ...
9
votes
3answers
4k views

Why does initramfs mount the root filesystem read-only

What is the reason for the root filesystem being mounted ro in the initramfs (and in initrd). For example the Gentoo initramfs guide mounts the root filesystem with: mount -o ro /dev/sda1 /mnt/root ...
9
votes
2answers
4k views

What is Arch Fallback in Arch boot menu?

What is exactly "Arch Fallback" in the Arch boot menu?
9
votes
1answer
3k views

How can you schedule a computer to boot at a specific time?

Usually BIOSes have an option to schedule a time to which to boot at. Is there a Unix/Linux interface to specify the scheduled boot?
9
votes
1answer
32k views

Booting linux from usb using EFI

I need to use a USB drive as an installation media for my Mint and Ubuntu. For that I have unetbootin to make the usb bootable. But my PC only supports EFI boot (while adding the boot device, I need ...
9
votes
1answer
10k views

Enable num-lock as default in Linux

There has been a similar question - but IMHO there has to be a simpler solution. If num-lock is on in the BIOS - why is it turned off during linux boot and/or KDE/Gnome/whatever startup?
9
votes
3answers
10k views

Does initramfs use /etc/fstab?

The way I understand it, initramfs is responsible for loading the "real" root filesystem. Now, there are two places where we define that root. First we put an entry in /etc/fstab. Second, we put the ...
9
votes
3answers
12k views

How to install GRUB to a whole ext4 disk without partition table?

Currently I have the entire disk /dev/sda formatted as ext4, and installed Gentoo. (There is no MBR, no partition at all. ) But finally, I can't install GRUB on it, because it seems like GRUB needs ...