Ubuntu Linux

# Moving /var

After moving `/var` to a separate partition, Ubuntu will not boot anymore. This is caused by Ubuntu needing the directories `/var/run` and `/var/lock` **before** `/var` is mounted. The solution is simple: Just create `/var/run` and `/var/lock` on the root partition and Ubuntu will boot again.

6

7

# Installing the Developer Tools

8

9

The basic developer tools (e.g. C compiler) can be installed by installing the virtual `build-essentials` package.

10

11

# Switching from MBR to GPT and UEFI Boot

12

13

In this scenario, we have a harddisk that is formatted with an MBR and has Windows 7 and Linux installed on it. We want to change this to GPT (and hence to UEFI).

14

15

As far as I can tell, there is no feasible way to convert Windows to GPT and UEFI boot without reinstalling it. In my case this was fine, because major parts of the computer's hardware (mainboard and CPU) had been changed and Windows does not handle these kind of changes well anyway. So here is the step by step process that worked for me:

16

17

Be sure to make a backup of your computer's harddisk. As part of this process some data has to be deleted and there also is a chance to lose more data, because something goes wrong.

18

19

Boot from the Ubuntu 12.04 LTS Desktop CD (64-bit). Make sure to boot in UEFI mode. You can either disable PC-BIOS mode in your computer's boot setting or select the UEFI mode in the computer's boot select menu. How to do this strongly depends on your computer's mainboard.

20

21

Add the Universe repository to the software sources and install `gdisk`. Probably it is a good idea to make a backup of your harddisk's MBR using `dd`. For the rest of this guide we assume that your disk drive is `/dev/sda`. So run `sudo gdisk /dev/sda`. `gdisk` will automatically [convert your disk from MBR to GPT](http://www.rodsbooks.com/gdisk/mbr2gpt.html), keeping the partitions (if possible). Now you have to delete the Windows "reserved" and system partitions. Typically, these are the first two partitions on the disk. Now exit `gdisk` saving the changes.

22

23

Shutdown the Ubuntu system and boot from the Windows 7 installation DVD (in UEFI mode). The Windows 7 installer can automatically create the needed partitions in the free area of the disk, that you created by deleting the Windows partitions earlier. It will create three partitions: Two special ones mainly needed for booting and a regular one for the Windows system partition.

24

25

When the installer rebooted, I got a funny error every time I tried to boot from the harddisk. I got a blue screen with an error code of 0xc0000225. After some time I [figured](http://forums.anandtech.com/showthread.php?t=2260563) [out](http://www.computerbase.de/forum/showthread.php?t=1152436) that this was caused by the second harddisk in the computer being formatted using MBR. After converting this disk to GPT, everything worked smoothly. Windows is supposed to support mixed GPT and MBR disks in the same system, however in some causes it seems to cause trouble.

26

27

After the Windows installation has finished, we can boot back into Ubuntu using the Ubuntu 12.04 LTS Desktop CD. Again, we have to boot in UEFI mode.

28

29

We have to change to the target system by mounting all required partitions and chrooting to the target system. How to do this exactly depends on your system layout. In my case, I had the boot partition on /dev/sda4 and all other partitions in LVM. Therefore, I first installed the `lvm2` package, activated the volume group `vg0` with `vgchange -a y vg0` and mounted all required filesystems with the commands

30

31

```bash

32

sudo mount /dev/vg0/root /mnt

33

sudo mount /dev/vg0/home /mnt/home

34

sudo mount /dev/sda4 /mnt/boot

35

sudo mkdir /mnt/boot/efi

36

sudo mount /dev/sda1 /mnt/boot/efi

37

sudo mount -o bind /dev /mnt/dev

38

sudo mount -o bind /dev/pts /mnt/dev/pts

39

sudo mount -o bind /proc /mnt/proc

40

sudo mount -o bind /run /mnt/run

41

sudo mount -o bind /sys /mnt/sys

42

```

43

44

In this example the system's ESP (this is the partition where the EFI boot-loaders are stored) has been created by the Windows setup as `/dev/sda1`.

45

46

Now we can change into the target system:

```

sudo su -

chroot /mnt

```

You should make a backup of the GRUB configuration files before proceeding. The relevant files are in `/boot/grub`, `/etc/default/grub` and `/etc/grub.d`.

54

55

Now you should purge all GRUB packages. You can usually do this by running `aptitude purge "?name(grub-)" "?name(grub2-)"`.

56

57

Next you should delete all remaining GRUB files (`/boot/grub`, `/etc/default/grub` and `/etc/grub.d`). Then you should create a symbollink in `/boot` that points to the install location of GRUB in the ESP: `ln -s efi/EFI/grub /boot/grub`.

58

59

After that you can install the EFI version of GRUB: `aptitude install grub-efi`.

60

61

In the target system, we have to edit `/etc/fstab` and add an entry for the ESP. You can find out the UUID of the partition by running `grub-probe --target=fs_uuid /boot/efi`. Then add a line like

62

63

```

64

UUID=<UUID> /boot/efi vfat defaults 0 1

65

```

66

67

to your /etc/fstab (of course you have to replace `<UUID>` by the UUID printed by `grub-probe`.

68

69

Now we install GRUB with `grub-install --boot-directory=/boot/efi/EFI --bootloader-id=grub --no-floppy --recheck` (I got this from [another guide](http://thinkpad-forum.de/threads/123262-EFI-Grub2-Multiboot-HowTo)).

70

71

You might have to edit `/etc/default/grub` to suit your needs. I disabled the OS prober (because it does not detect the UEFI Windows loader anyway but found some old systems on my second harddisk) by adding `GRUB_DISABLE_OS_PROBER="true"`. I also changed `GRUB_HIDDEN_TIMEOUT` to the empty string and `GRUB_HIDDEN_TIMEOUT_QUIET` to `false`. This was needed because the OS prober was disabled and thus GRUB would not show the boot menu by default any longer (the same would happen if OS prober was enabled but it did not find other operating systems).

72

73

Because memtest86+ was installed on the system, I had to copy the file `20_memtest86+` from the backup of the GRUB configuration files back to `/etc/grub.d`.

74

75

In order to be able to boot Windows 7 from GRUB (using the boot menu of the EFI BIOS is inconvenient), I added an extra entry to `/etc/grub.d/40_custom` (as describe in the [Ubuntu Community Wiki](https://help.ubuntu.com/community/UEFIBooting#Chainloading_Windows_x86_64_UEFI-GPT)):

76

77

```

78

menuentry "Windows 7 (UEFI)" {

79

search -fs-uuid --no-floppy --set=root <UUID>

80

chainloader (${root})/EFI/Microsoft/Boot/bootmgfw.efi

}

```

In this example `<UUID>` again has to be replaced by the UUID of the ESP.

85

86

In order to generate the GRUB configuration file, `update-grub` needs to be run.

87

88

Finally, GRUB has to be registered in the EFI settings. This can be done by running `efibootmgr --create --gpt --disk /dev/sda --part 1 --write-signature --label "GRUB" --loader "\\EFI\\grub\\grub.efi"`.

89

90

After finishing these steps, you can leave the target system and unmount all partitions. Finally, reboot the computer and select GRUB from the computer's boot menu. Now you should see the normal GRUB screen, where you can select to boot Linux or Windows.

91

92

# Configuring the Vino VNC server on Ubuntu Desktop

93

94

## Allowing access from localhost only

95

96

```bash

97

gsettings set org.gnome.Vino network-interface lo

98

```

99

100

This is perfect if there is only a single user on the machine because this way, a SSH tunnel can provide sufficient access restrictions.

101

102

## Fixing problems with some VNC clients

103

104

Since Ubuntu 14.04 LTS, some (older) clients cannot connect. This seems to be caused by the use of TLS in the VNC server. This feature can be disabled (see [bug #1290666](https://bugs.launchpad.net/ubuntu/+source/vino/+bug/1290666)):

105

106

```bash

107

gsettings set org.gnome.Vino require-encryption false

108

```

109

110

## Find packages that have been removed but not purged

111

112

```bash

113

aptitude search "?config-files"

114

```

115

116

# Graphics server not starting after Upgrade to Ubuntu 22.04

117

118

If the graphics server (X11 / Wayland) is not starting on a system with a NVIDIA graphics card (in particular an older one – in my case it was a GeForce 210), this might be caused by the switch from the proprietary NVIDIA driver to Nouveau, without some files of the proprietary NVIDIA driver having been removed correctly.

119

120

Support for the old 340 version of the NVIDIA driver ended a while ago, so this version of the driver has been removed from Ubuntu 22.04. However, if this driver used to be install in Ubuntu 20.04 before the upgrade, it might still be installed after the upgrade and thus the configuration file `/etc/modprobe.d/nvidia-340_hybrid.conf` might still exist. This file will keep the open-source Nouveau driver from being loaded. This can typically be fixed by running `apt-get purge nvidia-340`.

Wiki source code of Ubuntu Linux

Applications

Navigation

Need help?

author	version	line-number	content
		1	{{toc/}}
		2
		3	# Moving /var
		4
		5	After moving `/var` to a separate partition, Ubuntu will not boot anymore. This is caused by Ubuntu needing the directories `/var/run` and `/var/lock` before `/var` is mounted. The solution is simple: Just create `/var/run` and `/var/lock` on the root partition and Ubuntu will boot again.
		6
		7	# Installing the Developer Tools
		8
		9	The basic developer tools (e.g. C compiler) can be installed by installing the virtual `build-essentials` package.
		10
		11	# Switching from MBR to GPT and UEFI Boot
		12
		13	In this scenario, we have a harddisk that is formatted with an MBR and has Windows 7 and Linux installed on it. We want to change this to GPT (and hence to UEFI).
		14
		15	As far as I can tell, there is no feasible way to convert Windows to GPT and UEFI boot without reinstalling it. In my case this was fine, because major parts of the computer's hardware (mainboard and CPU) had been changed and Windows does not handle these kind of changes well anyway. So here is the step by step process that worked for me:
		16
		17	Be sure to make a backup of your computer's harddisk. As part of this process some data has to be deleted and there also is a chance to lose more data, because something goes wrong.
		18
		19	Boot from the Ubuntu 12.04 LTS Desktop CD (64-bit). Make sure to boot in UEFI mode. You can either disable PC-BIOS mode in your computer's boot setting or select the UEFI mode in the computer's boot select menu. How to do this strongly depends on your computer's mainboard.
		20
		21	Add the Universe repository to the software sources and install `gdisk`. Probably it is a good idea to make a backup of your harddisk's MBR using `dd`. For the rest of this guide we assume that your disk drive is `/dev/sda`. So run `sudo gdisk /dev/sda`. `gdisk` will automatically [convert your disk from MBR to GPT](http://www.rodsbooks.com/gdisk/mbr2gpt.html), keeping the partitions (if possible). Now you have to delete the Windows "reserved" and system partitions. Typically, these are the first two partitions on the disk. Now exit `gdisk` saving the changes.
		22
		23	Shutdown the Ubuntu system and boot from the Windows 7 installation DVD (in UEFI mode). The Windows 7 installer can automatically create the needed partitions in the free area of the disk, that you created by deleting the Windows partitions earlier. It will create three partitions: Two special ones mainly needed for booting and a regular one for the Windows system partition.
		24
		25	When the installer rebooted, I got a funny error every time I tried to boot from the harddisk. I got a blue screen with an error code of 0xc0000225. After some time I [figured](http://forums.anandtech.com/showthread.php?t=2260563) [out](http://www.computerbase.de/forum/showthread.php?t=1152436) that this was caused by the second harddisk in the computer being formatted using MBR. After converting this disk to GPT, everything worked smoothly. Windows is supposed to support mixed GPT and MBR disks in the same system, however in some causes it seems to cause trouble.
		26
		27	After the Windows installation has finished, we can boot back into Ubuntu using the Ubuntu 12.04 LTS Desktop CD. Again, we have to boot in UEFI mode.
		28
		29	We have to change to the target system by mounting all required partitions and chrooting to the target system. How to do this exactly depends on your system layout. In my case, I had the boot partition on /dev/sda4 and all other partitions in LVM. Therefore, I first installed the `lvm2` package, activated the volume group `vg0` with `vgchange -a y vg0` and mounted all required filesystems with the commands
		30
		31	```bash
		32	sudo mount /dev/vg0/root /mnt
		33	sudo mount /dev/vg0/home /mnt/home
		34	sudo mount /dev/sda4 /mnt/boot
		35	sudo mkdir /mnt/boot/efi
		36	sudo mount /dev/sda1 /mnt/boot/efi
		37	sudo mount -o bind /dev /mnt/dev
		38	sudo mount -o bind /dev/pts /mnt/dev/pts
		39	sudo mount -o bind /proc /mnt/proc
		40	sudo mount -o bind /run /mnt/run
		41	sudo mount -o bind /sys /mnt/sys
		42	```
		43
		44	In this example the system's ESP (this is the partition where the EFI boot-loaders are stored) has been created by the Windows setup as `/dev/sda1`.
		45
		46	Now we can change into the target system:
		47
		48	```
		49	sudo su -
		50	chroot /mnt
		51	```
		52
		53	You should make a backup of the GRUB configuration files before proceeding. The relevant files are in `/boot/grub`, `/etc/default/grub` and `/etc/grub.d`.
		54
		55	Now you should purge all GRUB packages. You can usually do this by running `aptitude purge "?name(grub-)" "?name(grub2-)"`.
		56
		57	Next you should delete all remaining GRUB files (`/boot/grub`, `/etc/default/grub` and `/etc/grub.d`). Then you should create a symbollink in `/boot` that points to the install location of GRUB in the ESP: `ln -s efi/EFI/grub /boot/grub`.
		58
		59	After that you can install the EFI version of GRUB: `aptitude install grub-efi`.
		60
		61	In the target system, we have to edit `/etc/fstab` and add an entry for the ESP. You can find out the UUID of the partition by running `grub-probe --target=fs_uuid /boot/efi`. Then add a line like
		62
		63	```
		64	UUID=<UUID> /boot/efi vfat defaults 0 1
		65	```
		66
		67	to your /etc/fstab (of course you have to replace `<UUID>` by the UUID printed by `grub-probe`.
		68
		69	Now we install GRUB with `grub-install --boot-directory=/boot/efi/EFI --bootloader-id=grub --no-floppy --recheck` (I got this from [another guide](http://thinkpad-forum.de/threads/123262-EFI-Grub2-Multiboot-HowTo)).
		70
		71	You might have to edit `/etc/default/grub` to suit your needs. I disabled the OS prober (because it does not detect the UEFI Windows loader anyway but found some old systems on my second harddisk) by adding `GRUB_DISABLE_OS_PROBER="true"`. I also changed `GRUB_HIDDEN_TIMEOUT` to the empty string and `GRUB_HIDDEN_TIMEOUT_QUIET` to `false`. This was needed because the OS prober was disabled and thus GRUB would not show the boot menu by default any longer (the same would happen if OS prober was enabled but it did not find other operating systems).
		72
		73	Because memtest86+ was installed on the system, I had to copy the file `20_memtest86+` from the backup of the GRUB configuration files back to `/etc/grub.d`.
		74
		75	In order to be able to boot Windows 7 from GRUB (using the boot menu of the EFI BIOS is inconvenient), I added an extra entry to `/etc/grub.d/40_custom` (as describe in the [Ubuntu Community Wiki](https://help.ubuntu.com/community/UEFIBooting#Chainloading_Windows_x86_64_UEFI-GPT)):
		76
		77	```
		78	menuentry "Windows 7 (UEFI)" {
		79	search -fs-uuid --no-floppy --set=root <UUID>
		80	chainloader (${root})/EFI/Microsoft/Boot/bootmgfw.efi
		81	}
		82	```
		83
		84	In this example `<UUID>` again has to be replaced by the UUID of the ESP.
		85
		86	In order to generate the GRUB configuration file, `update-grub` needs to be run.
		87
		88	Finally, GRUB has to be registered in the EFI settings. This can be done by running `efibootmgr --create --gpt --disk /dev/sda --part 1 --write-signature --label "GRUB" --loader "\\EFI\\grub\\grub.efi"`.
		89
		90	After finishing these steps, you can leave the target system and unmount all partitions. Finally, reboot the computer and select GRUB from the computer's boot menu. Now you should see the normal GRUB screen, where you can select to boot Linux or Windows.
		91
		92	# Configuring the Vino VNC server on Ubuntu Desktop
		93
		94	## Allowing access from localhost only
		95
		96	```bash
		97	gsettings set org.gnome.Vino network-interface lo
		98	```
		99
		100	This is perfect if there is only a single user on the machine because this way, a SSH tunnel can provide sufficient access restrictions.
		101
		102	## Fixing problems with some VNC clients
		103
		104	Since Ubuntu 14.04 LTS, some (older) clients cannot connect. This seems to be caused by the use of TLS in the VNC server. This feature can be disabled (see [bug #1290666](https://bugs.launchpad.net/ubuntu/+source/vino/+bug/1290666)):
		105
		106	```bash
		107	gsettings set org.gnome.Vino require-encryption false
		108	```
		109
		110	## Find packages that have been removed but not purged
		111
		112	```bash
		113	aptitude search "?config-files"
		114	```
		115
		116	# Graphics server not starting after Upgrade to Ubuntu 22.04
		117
		118	If the graphics server (X11 / Wayland) is not starting on a system with a NVIDIA graphics card (in particular an older one – in my case it was a GeForce 210), this might be caused by the switch from the proprietary NVIDIA driver to Nouveau, without some files of the proprietary NVIDIA driver having been removed correctly.
		119
		120	Support for the old 340 version of the NVIDIA driver ended a while ago, so this version of the driver has been removed from Ubuntu 22.04. However, if this driver used to be install in Ubuntu 20.04 before the upgrade, it might still be installed after the upgrade and thus the configuration file `/etc/modprobe.d/nvidia-340_hybrid.conf` might still exist. This file will keep the open-source Nouveau driver from being loaded. This can typically be fixed by running `apt-get purge nvidia-340`.