Monday, July 15, 2019

How to install python on centos 7

Install Python 3.6.4 on CentOS 7 From a Repository

This is the easier method of the two for installing Python on your machine. Here, we simply add a repository that has the pre-compiled version ready for us to install. In this case, we are adding the Inline with Upstream Stable repository, a community project whose goal is to bring new versions of software to RHEL-based systems.

Step 1: Open a Terminal and add the repository to your Yum install.

sudo yum install -y https://centos7.iuscommunity.org/ius-release.rpm

Step 2: Update Yum to finish adding the repository.

sudo yum update

Step 3: Download and install Python.

This will not only install Python – but it will also install pip to help you with installing add-ons.
sudo yum install -y python36u python36u-libs python36u-devel python36u-pip
Once these commands are executed, simply check if the correct version of Python has been installed by executing the following command:
python3.6 -V
You have now finished installing Python 3.6.4 on your CentOS 7 machine, as well as installing a native Python package management tool called pip.

Method 2: Compiling Python 3.6.4 on CentOS 7 From Source Code

installing python 3.6.4 on CentOS 7This is the more complicated method of the two, and will take more time – however, this method gives you more control over what gets installed and what doesn’t. It can also be more secure at times, depending on where the software package is downloaded from.
Important: Keep in mind that your Yum package manager will not know that you have installed Python 3.6.4 (or any other software) if you install software by manually compiling the source code. This means that no updates will be available for your manually installed software.

Step 1: Install the development tools needed for compilation.

First, we will need the tools in order to be able to compile and install programs from their source code. To do this, we will install the group “Development Tools” through Yum itself:
sudo yum groupinstall -y "Development Tools"
Once this is done, move on to step 2.

Step 2: Download the Python source files.

First, we need to create a directory in which our install will take place. Make a directory with a name of your choosing, then enter the directory. Once you are in your new directory, enter the following command to download the compressed Python source file.
wget https://www.python.org/ftp/python/3.6.4/Python-3.6.4.tar.xz
Once the file is finished downloading, uncompress the file by using tar, then enter into the new directory that was just created:
tar -xJf Python-3.6.4.tar.xz
cd Python-3.6.4

Step 3: Run the configuration script.

Use the following command to have the installation software check your system before actually starting the installation process.
./configure
This command ensures that the install will work, along with creating a special ‘makefile’ that is unique to your system. This makefile is what you will use to install Python onto your system.

Step 4: Install Python.

Now we can finally execute the makefile. Run the following command to install Python onto your system. Note: This will take a few minutes. The speed of the compilation and install will depend on the speed of your processor.
First, we run the ‘make’ command which compiles the program.
make
Then, once that is finished, we can run the installation command.
make install
Once this command finishes, you will have installed Python successfully, along with pip and setuptools. From here, creating a virtual environment is easy, and coding and executing the latest Python code is now possible.

MySQL Backup and Restore Commands for Database Administration

How to Backup a Single MySQL Database?

To take a backup of single database, use the command as follows. The command will dump database [rsyslog] structure with data on to a single dump file called rsyslog.sql.
# mysqldump -u root -ptecmint rsyslog > rsyslog.sql

How to Backup Multiple MySQL Databases?

If you want to take backup of multiple databases, run the following command. The following example command takes a backup of databases [rsyslogsyslog] structure and data in to a single file called rsyslog_syslog.sql.
# mysqldump -u root -ptecmint --databases rsyslog syslog > rsyslog_syslog.sql

How to Backup All MySQL Databases?

If you want to take backup of all databases, then use the following command with option –all-database. The following command takes the backup of all databases with their structure and data into a file called all-databases.sql.
# mysqldump -u root -ptecmint --all-databases > all-databases.sql

How to Backup MySQL Database Structure Only?

If you only want the backup of database structure without data, then use the option –no-data in the command. The below command exports database [rsyslogStructure into a file rsyslog_structure.sql.
# mysqldump -u root -ptecmint -–no-data rsyslog > rsyslog_structure.sql

How to Backup MySQL Database Data Only?

To backup database Data only without structure, then use the option –no-create-info with the command. This command takes the database [rsyslogData  into a file rsyslog_data.sql.
# mysqldump -u root -ptecmint --no-create-db --no-create-info rsyslog > rsyslog_data.sql

How to Backup Single Table of Database?

With the below command you can take backup of single table or certain tables of your database. For example, the following command only take backup of wp_posts table from the database wordpress.
# mysqldump -u root -ptecmint wordpress wp_posts > wordpress_posts.sql

How to Backup Multiple Tables of Database?

If you want to take backup of multiple or certain tables from the database, then separate each table with space.
# mysqldump -u root -ptecmint wordpress wp_posts wp_comments > wordpress_posts_comments.sql

How to Backup Remote MySQL Database

The below command takes the backup of remote server [172.16.25.126] database [gallery] into a local server.
# mysqldump -h 172.16.25.126 -u root -ptecmint gallery > gallery.sql

How to Restore MySQL Database?

In the above tutorial we have seen the how to take the backup of databases, tables, structures and data only, now we will see how to restore them using following format.
# # mysql -u [username] –p[password] [database_name] < [dump_file.sql]

How to Restore Single MySQL Database

To restore a database, you must create an empty database on the target machine and restore the database using msyql command. For example the following command will restore the rsyslog.sql file to the rsyslogdatabase.
# mysql -u root -ptecmint rsyslog < rsyslog.sql
If you want to restore a database that already exist on targeted machine, then you will need to use the mysqlimport command.
# mysqlimport -u root -ptecmint rsyslog < rsyslog.sql

Sunday, July 14, 2019

Solving the "Control D" error...Linux

Control D Error:-

Repair the file system By Using fsck command 

fsck /dev/sdb

Steps to Rectify it:-....

1) Enter the bootable Cd/DvD of Rhel.
(The version you are using)

2) Read the control D error carefully.

3) Give the root password.

4) You will go to single usermod.

5) Try to access /etc/fstab file.

6) Will not allow you as will be in read only mode.

7) Enter this command:-
mount -o remount,rw /
(Will give read/write permission to /)

8) Will give u read/write permission to all
the files in /

9)Then again enter into /etc/fstab & rectify ur error.(vim /etc/fstab)

10)Give command reboot or init 5(As per ur wish)


Rectify it & Enjoy the Control D Error.....

Tuesday, May 14, 2019

How to Download and Install RHEL8 Beta For Free (Red Hat Enterprise Linux)

RHEL (Red Hat Enterprise Linux) 8 beta was released on November 14, 2018, 4 years after the release of RHEL 7. This tutorial will be showing you how to download and install RHEL8 beta for free.Application Stream (AppStream) repositories allows delivering userspace packages more simply and with greater flexibility. Userspace components can now update more quickly than core operating system packages and without having to wait for the next major version of the operating system.
  • Supports more efficient Linux networking in containers through IPVLAN.
  • Includes a new TCP/IP stack with Bandwidth and Round-trip propagation time (BBR) congestion control.
  • System-wide Cryptographic Policies are also included.
  • Lightweight, open standards-based container toolkit (Buildah, Podman, Skopeo)
  • Red Hat Enterprise Linux Web Console provides a simplified interface to more easily manage Red Hat Enterprise Linux servers locally and remotely, including virtual machines
  • Yum 4, the next generation of the Yum package manager in Red Hat Enterprise Linux, delivers faster performance, fewer installed dependencies and more choices of package versions to meet specific workload requirements. Yum 4 is based on DNF technology.
  • Support for LUKSv2 to encrypt on-disk data combined with Network-Bound Disk Encryption (NBDE) for more robust data security and more simplified access to encrypted data.
RHEL 8 beta is based on Fedora 28. It includes newer software packages such as
  • Linux kernel 4.18,
  • Python 3.6, PHP7.2, Apache 2.4.35, Nginx 1.4
  • MariaDB 10.3, MySQL 8.0, PostgreSQL 10, PostgreSQL 9.6, and Redis 4.0
  • OpenSSL 1.1.1 and TLS 1.3 are both supported.
  • GNOME Shell has been rebased to version 3.28, using Wayland the default display server. X.org server is available as well.
  • nftables replaces iptables. The firewalld daemon now uses nftables as its default backend.

RHEL8 Beta ISO file Download Link:

  • Intel/AMD 64-bit                https://red.ht/2ROrd80
  • IBM Power little endian     https://red.ht/2FnoQb6
  • IBM z Systems                    https://red.ht/2RUif9k
  • ARM 64-bit                         https://red.ht/2DmPZbn
You can download ISO file in your browser or use wget to download in terminal like below. Use -Ooption to specify the filename to save as.
wget https://red.ht/2ROrd80 -O rhel8-beta-x64.iso
Once it’s downloaded, you can create a bootable USB with dd command like below on a Linux desktop OS. /dev/sdX is the device name of your USB drive, which can can be obtained by running command sudo parted -l.
sudo dd if=rhel8-beta-x64.iso of=/dev/sdX status=progress
On Windows, you can create a bootable USB with Rufus. If you like to install RHEL 8 beta in VirtualBox, there’s no need to create bootable USB drive.

Installing RHEL 8 Beta in VirtualBox

First, create a virtual machine in Virtualbox. I set the memory size to 2048MB.
create a virtual machine for rhel8
The disk size is set to 15GB.
install rhel8 in virtualbox
After the VM is created, go to Settings -> Storage. Select the empty optical drive in Controller: IDE. Then choose RHEL 8 beta ISO as the optical disk file. Click OK to save your settings. Now your VM can be booted from the ISO file.

RHEL 8 beta virtualbox
Now start your VM. Choose the first option to install RHEL 8 beta.
install red hat enterprise linux 8 in virtualbox
After the installer is started, choose your language. (In Virtualbox, you can press to right Ctrl key to release the mouse cursor back to the host.)
rhel 8 installer
We know this a beta release, so click I want to proceed.

rhel 8 beta pre-release
On the next screen, you need to complete items marked with a yellow triangle icon. For example, I need to configure Installation Destination.
rhel 8 installation summary
Since this is installed in Virtualbox, I don’t want to set up a custom partition table. So I just click Donewithout making any changes.
rhel 8 installation destination
In software selection, I can choose Workstation as the base environment so that I will have a GUI.
rhel 8 workstation

In system purpose section, I can choose Development/Test for the usage. This is required if you want to use RHEL 8 beta for free. Leave other options untouched.
rhel 8 system purpose development test
After saving the configurations, click Begin Installation button. While the OS is being installed, you need to set a root password and create a user account.
rhel 8 create user
The installation is pretty fast. After 8 minutes, my RHEL 8 beta is installed. Before click the Reboot button, you need to go to Virtualbox Settings -> Storage and remove your ISO file from the virtual disk drive. Then click Reboot to enjoy the new OS.
On the first boot, you need to accept the license agreement.
rhel 8 license agreement
After that, click finish configuration. And log into the desktop.
rhel 8 workstation login
After you get through the welcome and get started screen, make sure your system has Internet connection. Then you can open up a terminal window and run
sudo yum update
It will tell you that
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.

Register your system to Red Hat subscription management (For Free)

You probably have heard that Red Hat products cost money, but you can use RHEL 8 for free via the Red Hat Developer Program , which costs $0 to join. It allows individual developer-use of RHEL. Integration, test and production environments will require a paid subscription.
red hat developer program
After you developer account is created, you need to go to https://www.redhat.com/wapps/sso/login.html to complete your profile.
red hat subscription manager
After that, run the following command in terminal to register your system.
sudo subscription-manager register --username your--redhat-developer-username --password your-password
Then run the following command to attach your system to a subscription.

sudo subscription-manager attach --auto
If everything went well, you should see:
Installed Product Current Status:
Product Name: Red Hat Enterprise Linux for x86_64 Beta
Status: Subscribed
Now you can update your repository.
sudo yum update
And install some software.
sudo yum install nginx
Enjoy Red Hat Enterprise Linux 8 beta for free!
If you see the following error while running yum command,
This system is registered with an entitlement server, but is not receiving updates. You can use subscription-manager to assign subscriptions.
There are no enabled repos.
That means your system can’t be attached to a subscription. You need to go to Red Hat customer portal, click Learn more about the beta button, then click get started button to add the Red Hat entreprise Linux server beta subscription, which is free.
That’s it! I hope this tutorial helped you download and install Red Hat Enterprise Linux 8 beta. As always, if you found this post useful, then subscribe to our free newsletter to get more tips and tricks. Take care 🙂

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RHEL 8.0 beta released

As the more observant among you may have noticed, the RHEL 8.0 beta dropped today.

To avoid the many "when can we expect the CentOS 8 beta" questions that usually come up, CentOS does not build beta versions so there will be no CentOS 8 beta. The first CentOS 8 will be the rebuilt RHEL 8.0 GA once that comes out upstream in however long it takes them to release it.

The RHEL 8 beta is free to download and you are encouraged to do so, experiment with it and give your feedback to Redhat in order to improve the final result.

https://www.redhat.com/en/blog/powering-its-future-while-preserving-present-introducing-red-hat-enterprise-linux-8-beta
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8-beta/
http://downloads.redhat.com/redhat/rhel/rhel-8-beta/README

Red Hat Enterprise Linux 8

Red Hat Enterprise Linux 8 was released on 2019-05-07, and everyone is waiting to find out when the CentOS rebuild will occur. This document is meant to cover general questions and timeline for what is happening.
A CentOS major release takes a lot of planning and changes in tooling as it is based on a much newer version of Fedora than previous versions. This means that everything from the installer, packages, packaging, and build systems need major overhauls to work with the newer OS. This means that there is always a ramp up period depending on the changes needed to make a rebuild work. The differences between EL-8 and EL-7 are no exception as the kernel has changed drastically, the repository format has added 'modules' and RPMS have grown many features that EL7 and before do not have. About the only item which has not drastically changed between EL7 and EL8 is the init system which is still systemd. [This is a first as EL5 had SysV, EL6 had Upstart, and EL7 had Systemd].

General Steps

Steps needed to make a CentOS rebuild usually follow these steps:
  1. Red Hat makes the sources available.
    1. This used to be done via src.rpms but 7 changed to git repos
    2. In 8 CentOS has partnered closer with Fedora and will be sharing git repos with the Fedora system
    3. The pushes from Red Hat started on 2019-05-07 and ended 2019-05-08
  2. CentOS needs to look at the sources and determine what is needed to build these packages
    1. The rpm format has added items like Suggests which change some tooling requirements
    2. The packaging format has moved from yum to dnf4/yum4 which added modularity. Modules are an additional hurdle because they allow parallel available versions of software but not parallel installability (aka you can build perl-5.24 and perl-5.26 and all perl modules need to be compiled against both sets.) Module stream versions are tied to certain timestamps which means you can't rebuild the RHEL or Fedora and get the exact same version name.
    3. There are always packaging loops which need to be worked out. You need golang-(X-1) to build golang-X but golang-(X-1) doesn't exist yet.. how do you build a version and break the loop?
  3. CentOS needs to set up a build system which can allow for these changes.
    1. While CentOS can use the Fedora build system as a template, there are items in it which don't make sense for CentOS.
    2. The EL-8 beta was useful but there are still major changes which need rethinking
  4. CentOS needs to go through the source code and find out all the places where debranding is needed.
    1. No you can't just "sed s'/Red Hat/CentOS/' (someone always offers that)
    2. There are times when you do replace and times when you don't.
  5. Builds can start occurring through the system
    1. This usually requires a multi-loop as you do a build to get started
    2. Then rebuild that core with itself
    3. Then add some more and possibly repeat 1 && 2 a couple of times.
    4. Then you can start building out the rest of the packages
  6. The installer usually takes a certain amount of work to get packaged together.
    1. Some things need additional patches
    2. Some things just need to be ordered correctly
    3. Some things like shim signatures for Secure Boot take outside review by signing authority
  7. QA work can begin
    1. with testing of packages by themselves or building from them
    2. with installer testing for smoke tests
  8. Usually some sort of RC work is done
  9. A final build is released
The above is a 'you asked the people trying to build the train when it will arrive' guide. That said, every release is different and the order and additional steps get found and added each time.

Architectures

Main architectures

The following arches are built automatically in parallel in our new Build System :
  • x86_64
  • ppc64le (Little Endian
  • aarch64 (ARM64, ARMv8)
Responsability, Owner: CentOS Core SIG

AltArch

The following architecture (not existing upstream, so more difficult to boostrap) is also actually being worked, on, but mainly based on a combination of Fedora 27/28 pkgs that can be used to bootstrap the el8 beta rebuild and then iterating loops until we can include that architecture in our Koji Build System .
  • armhfp (ARM32, ARMv7 - aka armv7hl)
Responsability, Owner : CentOS SIG-AltArch

Current Timeline

Item
Started
Ended
Status
Sources pushed to CentOS Git
2019-05-07
2019-05-08
DONE
Source code evaluation
2019-05-07
YYYY-MM-DD
Ongoing
New Build System Setup
2019-05-07
2019-05-08
DONE
Debranding patches added
2019-05-07
YYYY-MM-DD
Ongoing
Artwork Requested
2019-03-07
2019-05-07
DONE
2019-05-09
YYYY-MM-DD
Ongoing
Build Loop 0
2019-05-07
2019-05-??
Ongoing
Build Loop M
YYYY-MM-DD
YYYY-MM-DD
Not started
Build Loop N
YYYY-MM-DD
YYYY-MM-DD
Not started
Installer work
YYYY-MM-DD
YYYY-MM-DD
Not started
QA work
YYYY-MM-DD
YYYY-MM-DD
Not started
RC work
YYYY-MM-DD
YYYY-MM-DD
Not started
Release work
YYYY-MM-DD
YYYY-MM-DD
Not started

Definitions


  • DONE - Step is completed
  • Ongoing - Work is progressing
  • Not started - This step may requires work from another step to reach some completion or requires time from person who is working on other parts.
  • Build loop 0 - Getting an initial set of packages together which can then build more packages
  • Build loop 1 - Using the smallest set of packages to build a larger set which can then build more packages
  • Build loop N - I really don't know how many loops this is going to be.. so we will use N nomenclature.
  • Installer work - there are usually some work needed to make the installer actually work with various things like secure boot or different fonts or 'oh they fixed that in an upgrade.img.. let us just short cut and put that here.'

How to install python on centos 7

Install Python 3.6.4 on CentOS 7 From a Repository This is the easier method of the two for installing Python on your machine. Here, we ...

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