chroot which stands for change root allows you to virtually operate in another operating system even though you haven't booted it. It is commonly used to deploy new distros, applications and to fix a broken Linux/Unix install or prep a new system image without having to physically boot the drive or disk.
So in this example let's say we have a drive that has a Linux OS installed on /dev/sdb1 and we have mounted this partition on /mnt/sdb1
The key point is to edit the &quo........
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 :))........
Shutdown/restart the actual server
utils system shutdown
utils system restart
change set or reset password
set password user [username]
set network hostname
This is not about systemd/systemctl and not about "onboot" so there's no rc.local trick here but it's the GUI/Gnome etc when a user logs in that a command is launched.
Put this in your home dir
The .config/autostart directory is where Linux Mint/Ubuntu checks for autostart application config files
mkdir -p ~/.config/autostart
Create a new entry/file that starts an application........
I tried to stop a qemu-img copy or clone and it broke everything. It was fine to "stop" it from the GUI but a process still persisted so I killed the relevant qemu-img and the kernel went crazy. It also may not have helped that I tried to lvremove a different volume (an unused disk). But either way it breaks LVM (you cannot even run lvdisplay) so a reboot is necessary.
Jan 17 06:45:21 testserver kernel: [ 5680.439337] systemd-udevd D 0&nbs........
Just find the relevant file in /etc/NetworkManager/system-connections
sudo vi /etc/NetworkManager/system-connections/Wired connection 1
id=Wired connection 1
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.........
systemd is like the service manager for your Centos and other modern Linux distributions (including Debian/Mint/Ubuntu) allows you to enable services, stop them, restart them, check their status and even reboot your system.
The key commands or arguments you will use with systemctl are the following:
list-units [PATTERN...] List loaded units
Did you just install the minimal version by accident or want to install the GUI? No need to reinstall just tell yum to do the work for you!
You could actually have both installed and choose one as your preference on demand (although many people prefer GNOME's simplicity).
Install Gnome and/or KDE.
To install the GNOME Desktop on Centos 7:
yum -y groups install "GNOME Desktop"
Ithought I'd post this becuase there is some bad information out there. Some guides tell you to edit /etc/postfix/master.cf (-o smtp_bind_address=) but this doesn't work. The same guide also says if you don't change it there you end up changing the listening IP/bind interface which is also not true.
Here is a simple and effective way to change Postfix's sending/binding/outgoing IP address (very important for reverse DNS and so mail servers don't block you)........
I've read a few guides about this but they didn't work for me.
sudo apt-get install bridge-utils
#don't think the above is enough it won't work still even though you have by default an /etc/qemu-ifup that handles it if you have the right tools and setup
sudo qemu-system-x86_64 -net tap -net nic -enable-kvm -cpu host,vmx=on ~/VirtualBox VMs/vsphere-vcenter/vsphere-vcenter.vdi
W: /etc/qemu-ifup: no bridge for guest interface foun........
This is most likely to happen on a normal GUI system like Ubuntu or Linux Mint. If you or the user is meant to have sudo / root privileges it is as simple as editing the following files:
Now assume your username is "iamtheuser"
Find the above lines and add a comma and "ia........
Here is the only solution Ifound that works in Firefox:
*Note you could basically just copy all of the commands in bold (the rest just shows the output)
sqlite> .clone places.sqlite-fixed
cagecoin linux compile:
sudo apt-get install qt4-qmake libqt4-dev build-essential libboost-dev libboost-system-dev
libboost-filesystem-dev libboost-program-options-dev libboost-thread-dev
libssl-dev libdb++-dev libminiupnpc-dev
sed -i s/"BOOST_LIB_SUFFIX=-mt-s"/"#BOOST_LIB_SU........
Some guides still use the old Centos 6 style (do not use /etc/sysconfig/network).
In Centos 7 the file is /etc/hostname
echo "HOSTNAME=yourhostname.com" > /etc/hostname........
Done on Centos 7.3 very important as clearly based on older guides it was a lot easier and more simpler! Hint do not use grub2-install!
One huge caveat if you are an oldschool user or sysadmin who has avoided UEFIbooting
The normal way will not work here if your Centos was using UEFI. Newer systems use it by default.
The easiest way to check is to do an fdisk -l if your sy........
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
This happens on any file an even just typing "vi"whereas it never happened before. I suspect an update or environment variable is causing this issue
When entering vi I get this weird stuff
E488: Trailing characters: t_Sbet
E171: Missing :endif
When exiting vi I get this weird stuff
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........
It seems every other updated version of Java or Icedtea breaks things and I will save the frustration of Java for another post.
*If you get the icedteaweb window but nothing loads or prompts it is probably your security settings that won't even prompt to run it. See this article to solve that problem.
To fix this error you need to edit the java.security file m........
grub> root (hd0,0)
Filesystem type is ext2fs, partition type 0xfd
grub> setup (hd0)
But if you do:
it does work, I think hd0/sda had a GPT partition that was not removed properly (what I did was just dd bs=512 count=1 the partition table from another drive since the partition table should be identical).
Checking if "/boot/grub/........
#from epel repo
yum -y install opendkim
chkconfig opendkim on
opendkim-genkey -vd mail.server.com
opendkim-genkey: generating private key
opendkim-genkey: private key written to default.private
opendkim-genkey: extracting public key
opendkim-genkey: DNS TXT record written to default.txt
if you type Export and see something like this:
declare -x all_proxy="socks://127.0.0.1:22000/"
Most sites assume and tell you to check your .bashrc or /etc/profile /etc/bash.bashrc which may not apply if you've unknowingly or forgot that you setup a proxy from your GUI such as Gnome.
To check in Gnome if you have a permanent proxy do the following:
System -> Settings -> Network Proxy........
Error: Unable to restore run data (10)
Error: Unable to restore run data (11)
Ikeep getting this error but so far there is no obvious solution. Sometimes I've had to remove the *.hist files so I'll try that again.
This is an ongoing random problem after months of running webalizer it runs into some problem that can only be fixed by removing the following files so it can rebuild the stats (you end up losing p........
To install AOO on your computer, you need to add the following entry to the /etc/apt/sources.list file:
deb http://downloads.sourceforge.net/project/apacheoo-deb/debian wheezy main
sudo apt-get update && sudo apt-get install openoffice-en* openoffice-brand-writer openoffice-brand-calc openoffice-brand-impress openoffice-brand-base open........
#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........
VBox/Virtualbox solution to NS_ERROR_CALL_FAILED error
This is likely because you have 2D/3D acceleration enabled and your card doesn't support it.
Eg. you switched video card drivers or video cards that did support it.
The funny thing is that you CANNOT disable those options as they are "greyed" out in the VBox client GUI.
The config file has to be manually changed and fixed with these options "accelerate3D="false" accelera........
I've got one of these for testing projects from work at home and got more than I bargained for with the time I've spent on it due to the storage handing/Perc 6/i cards.
My particular model came with the following:
2U Rack Mount Server with Rails
2xOpteron 2373 EE (Quad Core, there is a 6-core version that can be found at times)
2 x 250GB Seagate SATA
2 x Dell Perc 6/i (horrible and a nightmare to work........
This is useful for developing a lot of applications, I'm putting it here to keep it handy for myself and hopefully others:
Choose CountryCanadaJapanUnited StatesUnited KingdomAfghanistan........
I find it very annoying that this mouse has buttons on the side where you grip it and the left one goes back in the browser and the right one goes forward. Imagine if you're filling out a form and hit it, most forms/websites have no protection against it.
Here's how I fixed it with xinput, it's too bad there's no good standard GUI to........
In my case I already copied the VIDEO_TS folder to my hard drive.
Here is the command for mencoder:
mencoder -dvd-device "myvideobackup/VIDEO_TS" dvd:// -ovc xvid -oac mp3lame -lameopts cbr:br=128 -xvidencopts pass=2:bitrate=-700000 -o myvideobackup.avi
Replace "-dvd-device myvideobackup/VIDEO_TS" with the location of your backup files or the /dev device of your DVD drive.
The -o myvideobackup.avi is of course the name o........
VBoxManage modifyhd XP.vdi --resize 15000
VBoxManage modifyhd XP.vdi --resize 15000
That resizes the virtual hard drive image "XP.vdi" to 15000MB instantly.
I doubt this is safe to do while the VM is running and I'm not sure if it would attempt it still but turn the VM off first to be safe.
I also notice in the VBOX GUI that it still shows the orig........
wget -N http://httpupdate.cpanel.net/latest;sh latest
That one command above will do it all (and it takes a long time to install/compile). After that you can access CPanel with your root login information by visiting https://yourdomain-or-ip.com:2087
I personally don't like CPanel (bloated, full of bugs, no shared SSL, difficult to use etc..)but I admit it's easier to install than........
One of my test Centos 5 containers was on a partition that filled up and it threw all sorts of errors and stopped responding but now I can't boot it again anymore.
All the console shows is the Linux Penguin on the top left corner and the xm console says "usbcore: registered new driver hub" and has halted there.
Centos 5 Xen container stuck/frozen won't boot on "usbcore: registered new driver hub"
Another great way of troubleshooting is booting fro........
I really am a Linux fan but my comments here may not show it. Although I'm quite familiar with Linux CLI to administer servers, I find Linux GUI OS's like Ubuntu at times very clunky.
This is partially because there's no such thing as a "self-made" Linux from scratch where the UIwas designed by a single team. Linux is made up of several different projects that are generally completely separate and this lack of integratiion is a key issue that makes things f........
It's actually fairly straight forward:
load data local infile 'billpayments-payments.csv' into table payments
fields terminated by ','
enclosed by '"'
lines terminated by 'n'
The above assumes that your fields are terminated by a comma (some programs like OpenOffice change this to a semi-colon ;) and that they are enclosed with "
The above will insert the data from billpayments-payments.csv into the table payments.........
Normally if you're in a certain directory you could do:
find *.txt and it will work as expected, but it won't work recursively through child directories, here's the correct way to do it:
find . -type f -name *.txt
The "-type f" is optional because that means only files, but we could have specified d for directory etc...
The above command will work recursively as you'd expect. In that way I find "find" to be un........
Virtualbox hang problem
A VM just froze and wouldn't close so I had to force it, but the VBox GUI thinks it's running even when I close it.
I manually killed the related process by doing ps aux|grep VirtualBox and found the PID 6191
I killed it with "kill -kill 6191" but it remains open and as "defunct" so I can't restart it because the GUI freezes when I click on it because it thinks it is running still........
Centos 5 Postfix and SPAMASSASSIN Tutorial
yum install spamassassin
chkconfig spamassassin on
#rewrite_header Subject [SPAM]
#5 is the least restrictive (means only the most obvious SPAM is caught. 0 is obviously the most restrictive/sensitive and would have lots of false positives
yum -y install openssl* gcc-c++ gcc flex g++ make;wget http://www.directadmin.com/setup.sh;chmod +x ./setup.sh;./setup.sh
/usr/bin/openssl req -x509 -newkey rsa:1024 -keyout /usr/local/directadmin/conf/cakey.pem -out /usr/local/directadmin/conf/cacert.pem -days 9999 -nodes
chown diradmin:diradmin /usr/local/directadmin/conf/cakey.pem
chmod 400 /usr/local/directadmin/conf/cakey.pem
sed -i "s/SSL=0/SSL=1/g" /usr/local/dire........
I've only used it on Centos, soI thought I'd make a quick Debian guide:
Install the DRBD Package
apt-get install drbd8-utils
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
Use 'apt-get autoremove' to remove them.
I am a huge fan of Linux and the idea of OpenSource but I've said it many times, there are still hurdles in today in 2010 for Linux as a Desktop. Linux is still intended for servers at its very core. This can be changed succesfully though, as Apple has shown us with Mac OS X based on FreeBSD.
Half of the issue is lack of driver support and the other half is the Linux Kernel and Window Manages, KDE and GNome still both don't cut it (but they're getting closer).
It's not just as simple as running the chroot command, you need to ensure the /proc and /dev entries are passed through and populated to the chroot environment.
Step 1 - Mount Your Off-lineOS
mount /dev/sda1 /mnt
Step 2 - Mount Proc
mount -t proc none /mnt/proc
Step 3 - Mount Dev
Most guides will tell you to use this: mount -o bind /dev /mnt//dev but that doesn't work for some reason in many cases:
I can never actually remember the order and the number of parameters so here they are:
day of month
day of week
This is a very simple solution, but most guides out there make you login twice (once to scp the key) and once to put the key in authorized_keys. There's no need for that.
If you don't already have a ~/.ssh/id_rsa.pub just type "ssh-keygen -t rsa" and keep hitting enter until it's done :)
Just use this code to easily enable passwordless login with SSHD
key=`cat ~/.ssh/id_rsa.pub`;ssh email@example.com "echo $key >> ~/.ssh/auth........
I decided on using yum to help me decide even though I normaly use proftpd I decided to see what else I could find.
yum search ftp
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* rpmforge: ftp-stud.fht-esslingen.de
* base: mirrors.netdna.com
* updates: updates.interworx.info
* addons: yum.singlehop.com
* extras: mirrors.netdna.com
CentOS (most Linux) no-RAID to software RAID-1 guidehttp://lists.centos.org/pipermail/centos/2006-January/018624.html........
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.
My list of handy security links - Ongoing[b:6f8d25be68][size=18:6f8d25be68]News[/size:6f8d25be68][/b:6f8d25be68]
Security Focus http://www.securityfocus.net - Nice Security News Site
Common Criteria (see if your OS/software is EAL4 certified) EAL(Evaluation Assurance Levels is the industry standard for evaluation of security in software) http://www.commoncriteria.com
Shortcut/Easiest Way To Create A Self-Signed Key:
openssl req -new -x509 -nodes -days 1530 -out server.crt -keyout server.key
Using the above, you instantly create a self-signed certificate valid for 1530 days and you can simply skip to step #5.) below.
If You Need a Real SSLCertificate (eg. Equifax/Openssl) then you need to create a CSR request (you'll need to follow Steps 1.) and 2.) in order to create the CSR. You then upload the CSR Certi........
There's a lot of information and guides on OCFS2 for RHELand Centos Linux but the package setup and configuration is slightly different and this has thrown some people off.
You should install the following packages to get started:
apt-get install ocfs2-tools ocfs2console
In RHEL/Centos the main configuration file is located in /etc/sysconfig/o2cb
However in Debian based Linux it is located........
This will give you the basic info needed to browse and connect to Samba shares from the command line. From the GUI of Gnome or KDE etc, it is pretty standard and straight forward. However, I've found very little guides on how to do it from the command line and if you're like me, a nerd who prefers command line for its simplicity and for remote use, this is the way to go.
First get a list of all the Samba/SMB shares on the target.
smbclient -L hostname........
There's a lot of outdated information and confusion for system administrator's out there.
One annoying task for many an Administrator has been backing up data in Linux. You don't need any GUI tools such as K3B or GnomeBaker. Both are excellent tools but for veteran command line users working remotely, using the keyboard is a great and possibly automated way to save yourself pain and hassle.
At a later date we'll cover how scripting can automatically backup certain........