Category: Linux

Ubuntu Slow Boot
Last day my PC become very slow to boot.
```
boby@ok-pc-01:~$ systemd-analyze 
Startup finished in 15.777s (kernel) + 3min 1.400s (userspace) = 3min 17.178s
graphical.target reached after 1min 47.169s in userspace
boby@ok-pc-01:~$ 
```
It take 3 minutes and 17 seconds to boot up.

This happend after i did some changes to my 2nd hard disk and added ZFS partition. First thing i thought it was ZFS that make my PC slow.

systemd-analyze blame did not show any useful info.
```
systemd-analyze blame
```
To find the problem, i edited the file
```
sudo  vi /etc/defaults/grub
```
Find the line
```
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
```
Replace it with
```
GRUB_CMDLINE_LINUX_DEFAULT=""
```
Now rebuild grub.cfg with
```
update-grub2
```
Rebooted the PC. Now instead of showing Ubuntu splash screen, you get lot of text, that shows what actually your PC is doing.

From the boot message i found system waiting 1 minutes 30 seconds for mounting one of the disk partition. This is because i re-partitioned my 2nd hard disk and forget to remove the disk from /etc/fstab.

I removed the non existant disk entry from /etc/fstab and rebooted PC. Now it boot much faster.

See Ubuntu
June 22, 2018

Configure Networking in Fedora 28 OVH Proxmox

OVH have special networking requirement. First you need to login OVH and create vMAC for your IP address. Now create VM in Proxmox, during VM creation, specify this vMAC address under Network > MAC.

Once your VM is installed, you don’t have network access. Login to the server using Proxmox Console.

Run following commands

ip addr add FAILOVER_IP dev ens18
ip route add GATEWAY_IP dev ens18
ip route add default via GATEWAY_IP dev ens18

Replace following in above commands

FAILOVER_IP = IP address of your Virtual Machine.

GATEWAY_IP = This is gateway IP addres. This is IP address of your host machine (the server on which proxmox installed). Replace last digit with 254. For example, if your servers main IP is 123.123.123.142, then use 123.123.123.254 as gateway.

Here is an example

ip addr add 158.69.138.120 dev ens18
ip route add 192.95.29.254 dev ens18
ip route add default via 192.95.29.254 dev ens18

At this point, you will be able to login to server using SSH. You may not able to ping outside, for this, you need to edit /etc/resolv.conf and add nameserver entry.

vi /etc/resolv.conf

Add

nameserver 8.8.8.8

To make it permanant, edit

vi /etc/sysconfig/network-scripts/ifcfg-ens18

Find

BOOTPROTO=dhcp

Replace with

BOOTPROTO=static
IPADDR=FAILOVER_IP
GATEWAY=GATEWAY_IP
HWADDR=MY:VI:RT:UA:LM:AC
DNS1=1.1.1.1

Example

[root@ip120 ~]# cat  /etc/sysconfig/network-scripts/ifcfg-ens18
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=static
IPADDR=158.69.138.120
GATEWAY=192.95.29.254
HWADDR=02:00:00:46:f4:52
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=ens18
UUID=cf4c9d14-92ec-3475-94e2-797b405ac516
ONBOOT=yes
AUTOCONNECT_PRIORITY=-999
DEVICE=ens18
[root@ip120 ~]#

For routung, create

vi /etc/sysconfig/network-scripts/ifcfg-ens18-route

GATEWAY_IP - 255.255.255.255 ens18
default GATEWAY_IP

Example

[root@ip120 ~]# cat /etc/sysconfig/network-scripts/ifcfg-ens18-route
192.95.29.254 - 255.255.255.255 ens18
default 192.95.29.254
[root@ip120 ~]#

June 22, 2018

Setup ZFS file system in Ubuntu
ZFS file system allow you to take snapshot, this is great for backing up MySQL databases. Last day i setup 2 * 2 TB Hard disk on My PC as RAID 1 (mirror) using ZFS.

First install ZFS with
```
apt install zfsutils-linux
```
I created same size partition on both hard disks. You can use full disk if you want, but i created partition, so i can use first 100 GB of each disk for installing Operating system.

RAID 1

RAID 1 mirror data between 2 disks. Even if one of the disk die, your data will be safe.

To create RAID 1, run
```
zpool create tank mirror /dev/sdx3 /dev/sdy3
```
Here sdx3 and sdy3 is partition on my HDD. Replace it with your actual partition to be used with ZFS. Be carefull not to use wrong partition or you will lose data.

If you are using full disk, then use
```
zpool create tank mirror /dev/sdx /dev/sdy
```
RAID 0

RAID 0 is dangerous, only use if you don’t care about data or you have a backup. If one of the disk fails, you will lose all data.

To setup RAID 0, use
```
zpool create tank /dev/sdx3 /dev/sdy3
```
Pool

Once you create a ZFS pool with “zpool” command, it get auto mounted as “/pool-name”. In above cause, i used name “tank”.

Here is what i have on my PC
```
root@ok-pc-01:~# df -h | grep tank
tank/data             1.6T  371G  1.3T  23% /mnt/data
tank                  1.3T     0  1.3T   0% /tank
root@ok-pc-01:~# 
```
The 2nd entry is the ZFS pool tank.

Datasets

Datasets are like partitions. You can create multiple partitions inside your pool, they sare disk space. You can set disk quotas if needed, by default no quota per datasets are set.

In above example /tank/data is a datasets i use.

To create a data set, run
```
zfs create -o mountpoint=/mnt/data tank/data
```
Here “-o mountpoint” specify where you want to mount the new dataset.

zpool status

To see status for your ZFS file system, run
```
root@ok-pc-01:~# zpool status
  pool: tank
 state: ONLINE
  scan: none requested
config:

	NAME        STATE     READ WRITE CKSUM
	tank        ONLINE       0     0     0
	  mirror-0  ONLINE       0     0     0
	    sda3    ONLINE       0     0     0
	    sdc3    ONLINE       0     0     0

errors: No known data errors
root@ok-pc-01:~# 
```
See zfs
June 22, 2018

Add ISO Images to Proxmox

To add ISO images to proxmox server, login to server as user root, then go to folder “/var/lib/vz/template/iso”. You can download ISO for operating system you need to this folder.

cd /var/lib/vz/template/iso

For Debian 10

wget https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-10.5.0-amd64-netinst.iso

For Debian 9

wget https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-9.4.0-amd64-netinst.iso

For Fedora 28

wget https://download.fedoraproject.org/pub/fedora/linux/releases/28/Server/x86_64/iso/Fedora-Server-dvd-x86_64-28-1.1.iso

See proxmox

June 22, 2018

How to download Proxmox Container Templates (CT)
Proxmox allows you to create fully virtualized virtual machines and Linux Containers. Linux Containers are lightweight, and share kernel used by the host server.

Before you can create CT, you need to download templates.

To list all available CT images, run
```
pveam available
```
Download a template

To download a proxmox CT template, run
```
pveam download local ubuntu-18.04-standard_18.04-1_amd64.tar.gz
```
This will download and save template to folder “/var/lib/vz/template/cache/”

List available templates

To get list of all templates available on your installation, run
```
pveam list local
```
To update
```
pveam update
```
See Proxmox
June 22, 2018
Trying Out Archlinux
Archlinux is a popular rolling distro. You always get latest software with Arch, there is no new version release like Ubuntu/RedHat etc.. You are always on latest version of ArchLinux by updating your system. So it is like install once and use for ever. Generally ArchLinux have very positive review from users. So i wanted to try it.

Installing ArchLinux require some command line, if you are comfortable with any Linux, it will be an easy task. I had some problem with getting WiFi work once i have installed and booted to ArchLinux. I posted in ArchLinux forum, got solution quickly. I have to boot with USB again, chroot to ArchLinux installation, then install dhclient and iw packages required.

For connecting to WiFi from command line, i made my Wifi connection OPEN (no password) as connecting to WiFI network with password from command line is little more involving. Since i have no one near my house to steal my WiFi, don’t have to worry about keeping it Open while i am installing Arch.
```
ip link set wlxe8de270b3955 up
systemctl start dhclient@wlxe8de270b3955
iw dev wlxe8de270b3955 connect -w SSID
```
Here wlxe8de270b3955 is my wifi interface name.

Once i have internet on new Arch Install. I installed gnome with pacman
```
pacman -S gnome gnome-extra
```
When it asked for package selection, i selected all, this installed many unwanted stuff. I asked for some options, i selected default. Install need to download some 500 MB of files.

After install, i created a user for me to login.
```
useradd -m -s /bin/bash  MY_USER_NAME
passwd MY_USER_NAME
```
After reboot, i am able to login to GNOME. I don’t like the default theme. I installed some dark theme using pacman. I don’t like it much, but that is all i can find on a quick search. I may need to spend more time to find a theme i like.

Next i need to install Visual Studio Code, that is the text editor i use. This is not available to install from pacman. Had to use AUR to install.

https://aur.archlinux.org

I searched for Microsoft Visual Code, found

To install, i have to clone the repo on the page. I done
```
mkdir ~/builds
cd ~/builds
sudo pacman -S git
git clone https://aur.archlinux.org/code.git
cd code
makepkg -si
```
This asked some questions to install dependency packages. I pressed yes. It installed many software like nodejs and many other related softwares. I don’t like it, but i allowed it to continue as i may able to use some of the sofware, many i will never use unless i am a Node.JS programmer. Next it started downloading Visual Code repo. This going to take some time as it need to pull all the commits. Then compile from source. Not something i will enjoy. So i decided to CTRL+C.

ArchLinux is not for me

For now i decided to stay with Ubuntu. I like color scheme better. Ubuntu was using Unity desktop, with Ubuntu 18.04, they switched to using GNOME destop. This made me want to try other distos using GNOME. I tried fedora, archlinux and Budgie Desktop. But for me Ubuntu feels much more polished and better looking. Maybe because i am using it for years now, so switching to another DE may take time. ArchLinux will stay on my 2nd HDD, so i can boot and play with it when i need to try something new.

ArchLinux will give me latest software. This is good, but for normal use, you may not find any differnce. For example Arch have kernal version 4.17, Ubuntu have 4.15. But having new kernal is not going to make any differnce unless you have some shiny new hardware, that only work with newer kernal.

Softwares are more stable and polished in Ubuntu LTS. ArchLinux, it is fresh, have new features. In rare cases, new software can have bugs and you may face problem and have to find a solution.

Most software vendors provide package for Ubuntu and Redhat Linux. Since this provided in deb format, installing is quick, no compliation needed. For example, if i need to install Skype, Visual Studio Code or Sublime, i just go to provider web site, they provide download for Ubuntu, that you can install, you get latest software, they keep updated whenever new version is available.

With AUR, i am not sure how upgrades are done. I think it is like FreeBSD ports, so you need to handle upgrades your own.
June 19, 2018
Enable Hot Corner in Ubuntu 18.04
Hot Corner is a Gnome Feature that allows you to see all open windows (same as clicking Super key or clicking on Activites) by moving mouse to top left corner.

To see if hot corner is enabled or disabled, run
```
gsettings get org.gnome.shell enable-hot-corners
```
To enable hot corner, run
```
gsettings set org.gnome.shell enable-hot-corners true
```
EDIT: After using enable hot corner for a day, i found my mouse reach this corner accidetly multiple times. Seeing activites page unexpectedly when you want someting else is confusing. For Ubuntu, it is better to keep it disabled.

To disable, run
```
gsettings set org.gnome.shell enable-hot-corners false
```
See Ubuntu 18.04
June 19, 2018
sfdisk
sfdisk is a program to copy partition information. This is for disks with MBR partition. Use sgdisk if you have GPT partition table.

To save partition info, run
```
sfdisk -d /dev/sda > part_table
```
To restore
```
sfdisk /dev/sda < part_table
```
Copy Partition to Another Disk

This is useful when you setting up raid or when you want to replace a disk in raid.
```
sfdisk -d /dev/sda | sfdisk /dev/sdb
```
Once copied, you may need to run
```
sfdisk -R /dev/sdb
```
So Linux kernal will read the new partition.

See hdd
June 18, 2018
firewall
https://opnsense.org
June 18, 2018

selectorctl

selectorctl list all installed PHP (alt-php) versions in CloudLinux Server.

[root@titan ~]# selectorctl -l
4.4    4.4.9  /opt/alt/php44/usr/bin/php-cgi
5.1    5.1.6  /opt/alt/php51/usr/bin/php-cgi
5.2    5.2.17  /opt/alt/php52/usr/bin/php-cgi
5.3    5.3.29  /opt/alt/php53/usr/bin/php-cgi
5.4    5.4.45  /opt/alt/php54/usr/bin/php-cgi
5.5    5.5.38  /opt/alt/php55/usr/bin/php-cgi
5.6    5.6.36  /opt/alt/php56/usr/bin/php-cgi
7.0    7.0.30  /opt/alt/php70/usr/bin/php-cgi
7.1    7.1.18  /opt/alt/php71/usr/bin/php-cgi
7.2    7.2.6  /opt/alt/php72/usr/bin/php-cgi
[root@titan ~]#

CloudLinux

June 14, 2018

yum
Some useful yum commands when installation fails or stopped halfway
```
yum-complete-transaction
yum-complete-transaction --cleanup-only
yum history redo last
```
Red Hat Software Collections (RHSCL)
```
yum install rh-php56
scl enable rh-php56 bash
```
Selectively enable yum repos
```
yum update -v --disablerepo=* --enablerepo=cl*
```
yum commands
Maybe run: yum groups mark install
yum reinstall a package
yum repolist
Yum disable a repository
rpm
yum-config-manager
Download RPM package from yum repository
yum list all available packages in a repo

yum errors
June 14, 2018

Maybe run: yum groups mark install

When installing CloudLinux alt-php group, i get error.

[root@titan ~]# yum groupinstall alt-php
Loaded plugins: fastestmirror, rhnplugin, universal-hooks
This system is receiving updates from CLN.
Loading mirror speeds from cached hostfile
* EA4: 169.255.59.74
* cpanel-addons-production-feed: 169.255.59.74
* cloudlinux-x86_64-server-7: cl-mirror.fr.planethoster.net
Maybe run: yum groups mark install (see man yum)
No packages in any requested group available to install or update
[root@titan ~]#

This error is fixed by running

yum groups mark remove alt-php
yum groupinstall alt-php

See yum

June 14, 2018