This article about migrating to a CentOS 7 /8 RAID mdadm array has a lot of info but I wanted to focus specifically on what newer versions of CentOS 7 require to boot mdadm and what changes are necessary on CentOS 7.8+
CentOS 7 / 8 mdadm RAID booting requirements
This assumes you are chrooting into an existing install or using it to get a new deployment ready. However, these steps can........
There are lots of wrong answers out there perhaps for much older versions of LibreOffice.
Tools -> Options
Then under LibreOffice ->Application Colors below.
Change the Viisted and Univisted link colors
Now you should h........
This error implies that there may be an issue with Xorg or maybe your NVIDIA GPU cannot start or initialize:
35 laptop kernel: [ 2031.857704] nvidia: loading out-of-tree module taints kernel.
35 laptop kernel: [ 2031.857724] nvidia: module license 'NVIDIA' taints kernel.
35 laptop kernel: [ 2031.857725] Disabling lock debugging due to kernel taint
35 laptop kernel: [ 2031.873280] nvidia: module verification failed: signature a........
If you are using mint, delete the preference that stops snap from installing (as it is required for lxc)
sudo rm /etc/apt/preferences.d/nosnap.pref
1. Install lxd:
sudo apt install lxd
Issues install lxd or errors? Click here
Debian at this time does not have lxd so you'll need to use snap:
sudo apt in........
The Best Docker Tutorial for Beginners
We quickly explain the basic Docker concepts and show you how to do the most common tasks from starting your first container, to making custom images, a Docker Swarm Cluster Tutorial, docker compose and Docker buildfiles.........
This was done on a 2900 but applies to all the switches of the same era.
Step 1 - Power Cycle and enter recovery mode
If you have physical access you can power cycle and hold the mode button down for 15 seconds. After that the SYS light will flash on the switch and you will see the following screenshot.
If you don't have physical access (eg. it is a datacenter swich over console only) then power cycle and hit "Ctrl+Pause/B........
Just a quick note and warning is that if you are testing to see if EFIPXE booting works on a VM, MAKE SURE it actually works. For example Iinitially tested using my Distro's QEMU 2.5+dfsg-5ubuntu10.46 and ovmf BIOS firmware (OVMF supports EFI). However, I found on old versions of QEMU (like 2.5), EFIbooting with GRUB NEVER works so it may appear that you have made a mistake when everything is fine when you boot a physi........
apt install software-properties-common
apt install python3-pip
apt install python3.7 curl gnupg python3.7-dev git
ln -s /usr/bin/python3.7 /usr/bin/python3
pip3 install numpy keras_preprocessing
curl https://bazel.build/bazel-release.pub.gpg | sudo apt-key add -
echo "deb [arch=amd64] http://storage.googleapis.com/bazel-apt stable jdk1.8" | sudo tee /etc/apt/sources.list.d/bazel........
The problem is that by default ssh-keygen loves to generate an easy to crack 2048 bit key (RSA). Supposedly having a larger keysize helps such as 4096 or 8096 but it is thought to be useless still against Quantum computing.
How can I check my existing keysize and type?
ssh-keygen -lf /path/to/your/id_rsa.pub
The output will be something like below followed by the hash. The first number is the key size and the second part will b........
Downloading and compiling from source to get the latest version of Asterisk is really simple with this guide.
apt install gcc make g++ libedit-dev uuid-dev libjansson-dev apt install libxml2-dev sqlite3 libsqlite3-dev
tar -zxvf asterisk-16-current.tar.gz
If you get this error change y........
sudo pip3 install python-docx
[sudo] password for :
Downloading python-docx-0.8.10.tar.gz (5.5MB): 5.5MB downloaded
Running setup.py (path:/tmp/pip_build_root/python-docx/setup.py) egg_info for package python-docx
no previously-included directories found matching 'docs/.build'
warning: no previously-included files matching '.DS_Store' foun........
SSH helps keep us secure in many ways, one of those is the host-key fingerprint which is unique. If you have been connecting to an SSH server that you've made no changes to and suddenly ssh warns that the key doesn't match then you have a problem.
But how about connecting to an existing server for the first time on a new machine or client?
A lot of new clients calculate it using an SHA256 hash but it is not as easy on your host machine to produce the sam........
The strange thing is that usually the first install or two will work on any new machine but then it suddenly won't. I had this experience on QEMU 2.13 on a different machine. There is something finicky or buggy about the CUCM installer even when choosing the same virtual hardware specs.
QEMU PC emulator version 0.12.1 (qemu-kvm-0.12.1.2-2.506.el6_10.1), Copyright (c) 2003-2008 Fabrice Bellard
Uh oh, so you're working on some super l33t code or other stuff that is super important and Linux Mint's MATE or Cinnamon window manager freezes. This means maybe you can move your mouse but you can't click anything, you can't Alt + Tab to another program but everything appears to be working other than that.
The first thing you would do is Ctrl + Alt + F1 (or whatever virtual terminal you want) and get into the Linux bash prompt (the black screen where things really happen :))........
ln -s --force newfile.jpg existingsymlink.jpg
All you do is use the --force flag to force/update the existing one.
The above modifies a symlink called "existingsymlink.jpg" and points it to "newfile.jpg" as the source.........
Cisco's CUCM (Cisco Unified Communication Manager) is a system that combines voice, video, data and mobile products into a single unified management suite. At its core, the CUCMis like a "Super PBX" that controls the flow of all communications through an organization even single or multiple site deployments.
Cisco's CUCMmakes communication more effective and simple through centralized management and unification of communications resources.........
#mount the VCSA DVD
mount /dev/sr0 /mnt/cd
#alternatively you could mount the iso directly
mount -o loop vcsa.iso /your/mount/path
#for this purpose we are using the CLI installer on Linux
#no it's not going to be that easy you can't just run vcsa-deploy like that you need to use a template or configured .json file
Usage: vcsa-deploy [-h] [--version] [--supported-deploymen........
ALTER TABLE existingtable ADD newfieldname VARCHAR(255);........
ALTER TABLE thetable ADD newfield VARCHAR(255)
It's very simple just specify "the table" and then the newfield type........
Centos 5 is not supported running yum will produce an error like this:
YumRepo Error: All mirror URLs are not using ftp, http[s] or file.
Eg. Invalid release/
removing mirrorlist with no valid mirrors: /var/cache/yum/base/mirrorlist.txt
Error: Cannot find a valid baseurl for repo: base
Solution - Update this file CentOS-Base.repo
I am using a GTX 1060 but replace the download for the driver with the correct/current version for your particular card by visiting: http://www.nvidia.com/Download/index.aspx?lang=en-us
yum install automake curl openssl-devel libcurl-devel gcc gcc-c++
yum -y install kernel-devel-`uname -r`
yum -y install unzip
Jun 1 15:45:42 videoeditor-desktop org.mate.panel.applet.MintMenuAppletFactory: project_data:INFO Missing folder chosen by user:
Jun 1 15:45:42 videoeditor-desktop org.mate.panel.applet.MintMenuAppletFactory: project_data:INFO Removed missing file: MAH02949.MP4
Jun 1 15:45:57 videoeditor-desktop org.mate.panel.applet.MintMenuAppletFactory: ui_util:WARNING Icon theme media-playback-start not found. Will use backup........
1.) Replicate the number of partitions in your new drives.
I created 3 partitions of the same same size.
partition #1: +1G (/boot)
partition #2: +60G (swap)
partition #3: rest of it (/)
#note if you are using GPT/gdisk you need to create separate a partition at least 1MB in size (in my case I would a 4th partition and mark it type ef02).........
sudo fdisk /dev/sdh
WARNING: GPT (GUID Partition Table) detected on '/dev/sdh'! The util fdisk doesn't support GPT. Use GNU Parted.
WARNING: The size of this disk is 8.0 TB (8001563221504 bytes).
DOS partition table format can not be used on drives for volumes
larger than (2199023255040 bytes) for 512-byte sectors. Use parted(1) and GUID
partition table format (GPT).
The device presents a l........
Your server does not support SNI, so all of your SSL websites must use the same SSL certificate. An update to the certificate on an existing SSL website will affect all of your SSL websites, and new SSL websites must use the currently installed certificate.........
It is as simple as using the "-k" option for:
-k, --keep-old-files don't replace existing files when extracting
--keep-newer-files don't replace existing files that are newer than
It was hard to find this as I find most online payment processors don't just put the basic information in plain view.
Remember to set your sid (your seller id). The below can easily be turned into a scripted PHP template to integrate into your own custom or existing payment solution.
#count=10000 makes an image of 10000MB make sure your image is at least the same as your existing
dd if=/dev/zero of=yourimage.img bs=1M count=10000
# losetup -fv newimage.raw
# fdisk -cu /dev/loop0
# kpartx -a /dev/loop0
# dd if= of=/dev/mapper/loop0p1
# e2fsck -f /dev/mapper/loop0p1
# resize2fs /dev/mapper/loop0p1
# a lot of guides tell you to edit /etc/fst........
This can happen when you install RPMForge or other repos with the wrong architecture and here's how you fix it (simply uninstalling won't usually fix it):
yum clean all
yum -y install openvpn
Loaded plugins: fastestmirror, presto
Loading mirror speeds from cached hostfile
* base: mirror.its.sfu.ca
* extras: centos.mirror.nexicom.net
* rpmforge: mirror.cpsc.ucalgary.ca
Solution To The Following:
yum -y install zlib-devel
yum -y install e2fsprogs*
*** Cannot find /usr/include/et/com_err.h. (yum install libcom_err-devel) ***
Installation didn't pass, halting install.
Once requirements are met, run the following to continue the install:
Common pre-install commands:
This is something I often setup for clients because it's very helpful for people in datacenters, this allows custom OS installs on demand, you can customize it more by using kickstart etc.. but here's a base I use before customizing more:
This little script below will install everything you need to get booting by PXE Linux.
It also assumes you set a local IP (be sure not to overwrite your existing IP) on eth0:0 (note the :0) as 192.168.1.10 and it........
This may sound silly but there will be conflicts/issues with the default Centos repository so you have to use a third party like remi (I prefer not to do this but it's the only option unless you migrate your sites/data to another server or can stand some downtime-not an option IMHOon a production server).
You may need to upgrade to PHP5.3 to run Joomla or many other reasons.
Your host needs to use PHP 5.2.4 or higher to run this version of Jo........
This array is a RAID 1 and in this case 1 of the 2 drives failed (a WD drive and I've found them to be the weakest and most unreliable of any brand and are easily damaged/DOA when shipping them).
mdadm --manage /dev/md0 --add /dev/sdb1
The above assumes the array you want to add to is /dev/md0 and the device we are adding is /dev/sdb1
*One thing to remember is to make sure the partition you are adding is the correct size for the array. You can also g........
I like dd, although it only reads it, usually a read test of the entire disk will uncover if your hard drive is bad in some parts. This is a good thing to do at least once a month, a lot of times bizarre program behavior, laginess and crashing/unnmounting problems etc.. are due to a failing disc and SMART won't know it or indicate a problem:
We must also remember there's never a guarantee, I've found that ever since we moved to larger and more platters per drive with 1TB drives........
I was getting frustrated with trying to write a simple URL like this:
I used the htaccess code like this:
Rewriterule ^example-withdash$ / [R=301]
I also tried escaping the dash which I thought should have treated it as a literal but that didn't work either:
Rewriterule ^example-withdash$ / [R=301]
But it wouldn't work, apparently the "-" dash means don't substitute,........
Moving to RAID was a pain.
What you have to do is the following from an existing install:
Create your mdadm RAID 1 array on your spare hard drive.
Start it with the missing disk.
rsync the entire contents of your current / to the md partition.
Here's a good way of doing it:
rsync -Pha --exclude=/proc/* --exclude=/sys/* --exclude=/mnt/* /. /mnt/md2........
Create New RAID 1 Array:
First setup your partitions (make sure they are exactly the same size)
In my example I have sda3 and sdb3 which are 500GB in size.
mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/sda3 /dev/sdb3
mdadm: array /dev/md2 started.
Check Status Of The Array
*Note I already have other arrays md0 and md1.
You can see below that md2 is syn........
This was done on Centos butI think it's easier on Debian machines, the paths that it is set to use are tailored towards Debian, so there is some fiddling that needs to be done on Centos.
This is for chrooting ssh, but jailkit has other uses than just SSH jails but I won't cover them in this writeup.
1. Install jailkit
yum install jailkit
2. Setup Jail Home
chown root:root /home/ja........
This is a great way to use your ftp server space, for example on your web hosting account (althoughI believe many hosts don't allow storage like this), but if you have a VPS/Dedicated Server etc.., this would be perfect. Imagine how easy it is to work with an ftp account that you can just mount as a normal partition or directory in Linux, it would be great for backups etc..
curlftpfs - mount a ftp host as a local directory
Why would you want to downgrade the superblock? Old mdadm verisons like mdadm 2.5.6 only use the 0.90 superblock/metadata and new versions use 1,1.0,1.1 and 1.2 superblocks by default.
There are some annoying caveats with this, first of all the new superblocks (later than 0.90) CANNOT be read by GRUB, so you won't even be able to install GRUB. Even worse, old versions of mdadm CANNOT automatically detect arrays even if they were created with a new version of mdadm with th........
Before we start I take no responsibility for this, you should have a backup and if you make a mistake during this process you could wipe out all of your data. So backup somewhere else before starting this as a precaution, or make sure it's data you could afford to lose.
The RAID 1 Setup (Hardware Wise)
I've already setup my 2 x 1TB (Seagate) drives with identical partitions, make sure your new hard drive (the empty one) is setup like your curr........
Nice General Linux RAID 1 GuideFull examples/tutorials that should work for any Linux system using GRUB or LILO as the boot loader.
This is the only tutorial I've seen that clearly shows how you can convert an existing non-RAID system to software RAID1 remotely, without ever having to be at the computer. This is important for people who co-locate or rent dedicated servers that they may not have physical access to in a timely manner.
$somevariable = ........
Centos 4.3 x64 & VMWare Server Beta[code:1:6d0b2c8c2f]
The correct version of one or more libraries needed to run VMware Server may be
missing. This is the output of ldd /usr/bin/vmware:
linux-gate.so.1 => (0xffffe000)
libm.so.6 => /lib/tls/libm.so.6 (0xf7fbd000)
libdl.so.2 => /lib/libdl.so.2 (0xf7fb9000)
libpthread.so.0 => /lib/tls/libpthread.so.0 (0xf7fa7000)
libX11.so.6 => not f........
How to compile in Windows/DOSMingW is a free compiler project so start here:
I downloaded the core GCC compiler:
But it's missing even the standard C runtime libraries like "stdio.h"!
You may also need to add environment variables from the DOS command line.
Here is a simpl........
The New Chips on the BlockThe New Chips on the Block
By Bruce Gain
Story location: http://www.wired.com/news/infostructure/0,1377,67795,00.html
02:00 AM Jun. 13, 2005 PT
We have embarked upon a new era in x86 PC computing -- so say chip giants AMD and Intel following their launches of dual-core PC processors. So how will dual-core processing change your PC computing experience? Our FAQ should help you decide whether or when you sho........
Intruder detection device uses behavioural analysisIntruder detection device uses behavioural analysis
by Antony Savvas
Monday 13 June 2005
Symantec is introducing a new intrusion detection product that uses behavioural analysis to block potential attacks on enterprise networks.
The new Critical System Protection 4.5 system uses technology that Symantec acquired through last year’s purchase of Platform Logic. It is designed to protect deskt........
Asterisk Agent Login ProblemUsing the AgentCallbackLogin function I couldn't login
I knew I had my agents setup properly in agents.conf so why couldn't I login?
The reason is because agents.conf was missing the [b:994d7a34af][agents][/b:994d7a34af] context!
I just added [agents] above the existing agent declarations and then I was able to login as expected.
It took a lot of figuring out and reading though!........
MySQL Server 3.23 won't start after switching from 4.1I was using a 4.1 alpha version of mysql-server and some how version 3.23 of the client and 4.1 of the client were also both installed!
So I forced uninstalled everything because after trying and trying even though MySQL server was using the short 16byte password authentication I got some other errors.
After trying with the ports and having it fail because I had existing database data I force installe........
Changing field names[quote:91ea6831b6]ALTER TABLE [u:91ea6831b6]table_name[/u:91ea6831b6] CHANGE [i:91ea6831b6]existing_field_name[/i:91ea6831b6] [b:91ea6831b6]new_field_name[/b:91ea6831b6] INT(11);[/quote:91ea6831b6]........
Create Table with structure of another existing tableOk, this has many valid uses such as if you need to create backups or the ability to undo changes, you would want to create new tables with the same structure as another. Here is how you do it.
Also remember Indexes such as PRIMARY KEYS [b:7ed9581493]will not be preserved[/b:7ed9581493] so you will have to readd them manually.[/i:7ed9581493]
[code:1:7ed9581493]CREATE TABLE NewName AS SEL........
I've tried to find a good sensible solution to cluster with and each technology has it's pros and cons and there is no perfect solution and I've found a lot of "exaggerations" in the applications, benefits and performance of these different filesystems.
I first started off with DRBD and Ihave to say it does live up to the hype, is quite reliable (although it can be annoying to match up the kernel module and user applications since they must match and whe........
In Newer Linux Distros This Way Is Easiest and works on newer versions like Ubuntu, Mint, Fedora, Centos, Debian etc.
#if you are missing timedatectl this in newer distros like Ubuntu/Mint/Debian and are using a container like Docker then do "apt install systemd"
timedatectl set-timezone America/Vancouver
Replace the America/Vancouver with the correct timezone.
To see the list you can just type "timedatectl set........
As much of a computer nerd as Iam, I'm usually a late adopter to technology for a few reasons. Ifeel most new hyped technologies and electronics are mainly fads, and I'm also cheap.
Adopting later means you avoid the bugs, kinks and most importantly pay the lowest price, that's me being cheap again :)
I never read much about the iPhone but Isaw all the hype around it and until recently I wasn't a big fan of anything Apple until a few years ago I realize........
Icouldn't understand why on one system it took a few minutes to get the SSHlogin prompt when connecting to other systems. The other systems all had the UseDNS parameter set to no, which almost always resolves the login prompt delay.
The reason is Ubuntu and perhaps Debian and other distributions /etc/nsswitch.conf file
Edit yours to have the "hosts" line like so (notice that files and dns are the primary resolution choice........