Tag Archives: Linux

Linux

Install PIP on Centos 8

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Introduction

In this tutorial. How to install pip on Centos 8. Pip is a package management system that allows you to install, remove, and otherwise manage software packages written in Python.

How to Install PIP on Centos 8

Two Python versions are Python 2 and Python 3.

Install pip3 for Python 3

sudo dnf install python3

The output is as below:

[devopsroles@server1 ~]$ sudo dnf install python3
[sudo] password for devopsroles: 
Last metadata expiration check: 0:07:32 ago on Wed 02 Sep 2020 09:15:00 PM +07.
Dependencies resolved.
==========================================================================================================
 Package                  Architecture Version                                      Repository       Size
==========================================================================================================
Installing:
 python36                 x86_64       3.6.8-2.module_el8.1.0+245+c39af44f          AppStream        19 k
Installing dependencies:
 python3-pip              noarch       9.0.3-16.el8                                 AppStream        19 k
 python3-setuptools       noarch       39.2.0-5.el8                                 BaseOS          162 k
Enabling module streams:
 python36                              3.6                                                               

Transaction Summary
==========================================================================================================
Install  3 Packages

Total download size: 201 k
Installed size: 466 k
Is this ok [y/N]: y
Downloading Packages:
(1/3): python36-3.6.8-2.module_el8.1.0+245+c39af44f.x86_64.rpm            7.3 kB/s |  19 kB     00:02    
(2/3): python3-pip-9.0.3-16.el8.noarch.rpm                                7.1 kB/s |  19 kB     00:02    
(3/3): python3-setuptools-39.2.0-5.el8.noarch.rpm                          52 kB/s | 162 kB     00:03    
----------------------------------------------------------------------------------------------------------
Total                                                                      43 kB/s | 201 kB     00:04     
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                                                  1/1 
  Installing       : python3-setuptools-39.2.0-5.el8.noarch                                           1/3 
  Installing       : python36-3.6.8-2.module_el8.1.0+245+c39af44f.x86_64                              2/3 
  Running scriptlet: python36-3.6.8-2.module_el8.1.0+245+c39af44f.x86_64                              2/3 
  Installing       : python3-pip-9.0.3-16.el8.noarch                                                  3/3 
  Running scriptlet: python3-pip-9.0.3-16.el8.noarch                                                  3/3 
  Verifying        : python3-pip-9.0.3-16.el8.noarch                                                  1/3 
  Verifying        : python36-3.6.8-2.module_el8.1.0+245+c39af44f.x86_64                              2/3 
  Verifying        : python3-setuptools-39.2.0-5.el8.noarch                                           3/3 

Installed:
  python3-pip-9.0.3-16.el8.noarch                            python3-setuptools-39.2.0-5.el8.noarch       
  python36-3.6.8-2.module_el8.1.0+245+c39af44f.x86_64       

Complete!

Check version pip

pip3 --version

The output as below

[devopsroles@server1 ~]$ pip3 --version
pip 9.0.3 from /usr/lib/python3.6/site-packages (python 3.6)

To install and build Python modules with pip, you need to install the Development tools:

sudo yum install python3-devel
sudo yum groupinstall 'development tools'

Installing pip2 for Python 2

sudo dnf install python2
pip2 --version
sudo yum install python2-devel
sudo yum groupinstall 'development tools'

For example, I have installed two python3 and python2 on Centos 8 as below

[devopsroles@server1 ~]$ sudo yum list installed | grep pip
libpipeline.x86_64                          1.5.0-2.el8                           @anaconda 
platform-python-pip.noarch                  9.0.3-16.el8                          @anaconda 
python2-pip.noarch                          9.0.3-16.module_el8.2.0+381+9a5b3c3b  @AppStream
python2-pip-wheel.noarch                    9.0.3-16.module_el8.2.0+381+9a5b3c3b  @AppStream
python3-pip.noarch                          9.0.3-16.el8                          @AppStream
python3-pip-wheel.noarch                    9.0.3-16.el8                          @anaconda

Managing Python Packages with pip

Typically, you should use pip inside a virtual environment only. It is used when separating the Python execution environment, such as when you want to change the Python execution environment for each project or you do not want to keep the local environment dirty venv.

In this section, we will go through several basic pip commands.

To install a package

pip install flask

If you want to install a specific version of the package

pip install flask==1.0.0

Uninstall a package

pip uninstall package_name

Search packages

pip search "package_name"

View the full list of packages

pip list

List outdated packages:

pip list --outdated

To upgrade an already installed package

pip3 install --upgrade package_name

Check pip dependencies

pip check

List of packages that need updating

pip list -o

Show packages by package name == version

pip freeze

Useful when outputting to requirements.txt

pip freeze > requirements.txt

Package update

pip install  -U package_name

Update pip itself

pip install  -U pip

Checking the details of the package

pip show package-name

Conclusion

How to install pip on CentOS 8 and how to easily install and uninstall Python modules with pip. Thank you for reading the DevopsRoles page!

Linux

Initial Server Setup Centos 8

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Introduction

When launching a new server with CentOS 8, ensuring a secure and properly configured foundation is essential. Whether you’re setting up a VPS for the first time or deploying infrastructure for production, a systematic initial server setup will help harden your system and prepare it for future installations. In this guide, we’ll walk through the essential steps to Initial Server Setup CentOS 8 server – from creating a non-root sudo user to configuring your firewall and installing core utilities.

Update Your System

Before any configuration, ensure that your system is up to date. This not only secures your server but also ensures compatibility with future installations:

sudo dnf update -y
sudo dnf upgrade -y

Create a Sudo User and Granting Administrative Privileges

useradd devopsroles
passwd devopsroles
usermod -aG wheel devopsroles
su - devopsroles

The output terminal as below

Open a new terminal window

ssh devopsroles@SERVER_IP_ADDRESS

Disable SSH Root Login

We have new account. so, I can secure our server by disabling remote SSH account to the root account.

sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config_BK
sudo sed -i -e 's/PermitRootLogin yes/PermitRootLogin no/g' /etc/ssh/sshd_config
sudo cat /etc/ssh/sshd_config | grep PermitRootLogin

The output terminal as below

we need to restart the SSH

sudo systemctl reload sshd

Changing the hostname

sudo hostnamectl set-hostname server1.devopsroles.com

Setting Up a Basic Firewall CentOS 8

Firewalld is a firewall management tool for Linux operating systems. you need to make sure that the server firewall allows web access.

sudo firewall-cmd --add-service=http --permanent
sudo systemctl enable firewalld
sudo systemctl start firewalld
sudo systemctl status firewalld

Update CentOS 8 System

sudo yum check-update
sudo yum upgrade -y
sudo yum clean all

Install System Utilities

sudo yum -y install bind-utils net-tools  psmisc traceroute tree vim-enhanced wget

Conclusion

By following this initial server setup guide for CentOS 8, you’ve established a secure and functional baseline for your system. Creating a non-root user with sudo privileges, securing SSH access, enabling the firewall, and installing essential tools are critical steps to ensure stability, security, and readiness for production workloads. With this solid foundation, you’re now well-prepared to deploy applications, configure services, or automate infrastructure tasks confidently.

For ongoing security, remember to regularly update your system and monitor user access and services. If you’re planning to install a web server, database, or other services next, this setup ensures you start from a well-configured environment. I hope will this your helpful. Thank you for reading the DevopsRoles page!

Linux

Using Netdata to Monitor PHP-FPM

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In this tutorial, How to Monitor the PHP-fpm using Netdata on Centos 7. Netdata is a free open source. It is very easy to install and configure for real-time monitoring. Now, let’s go to Netdata to Monitor PHP-FPM.

PHP-FPM (FastCGI Process Manager) is an alternative PHP FastCGI. It is commonly used in LEMP ( Linux Nginx MySQL/MariaDB PHP) stack; Nginx uses PHP FastCGI for serving dynamic HTTP content.

Steps install and configure

  • Centos 7 Server or RHEL 7 Server
  • Install PHP and enable PHP-FPM status
  • Install Netdata and configure Monitor for PHP-FPM status.

1. How to Install PHP

For example, How to install PHP version 7.3 on Centos 7.

2. Enable the PHP-FPM status page.

Check php-fpm running on your system.

[root@DevopsRoles vagrant]# netstat -nplt | grep php-fpm
tcp        0      0 127.0.0.1:9000          0.0.0.0:*               LISTEN      4328/php-fpm: maste 
[root@DevopsRoles vagrant]# ps -ef | grep php
root      4328     1  0 21:50 ?        00:00:00 php-fpm: master process (/etc/opt/remi/php73/php-fpm.conf)
apache    4329  4328  0 21:50 ?        00:00:00 php-fpm: pool www
apache    4330  4328  0 21:50 ?        00:00:00 php-fpm: pool www
apache    4331  4328  0 21:50 ?        00:00:00 php-fpm: pool www
apache    4332  4328  0 21:50 ?        00:00:00 php-fpm: pool www
apache    4333  4328  0 21:50 ?        00:00:00 php-fpm: pool www
root      4381  3003  0 21:52 pts/0    00:00:00 grep --color=auto php

Configure file php-fpm status as shown.

$ sudo vim /etc/php-fpm.d/www.conf 
OR
$ sudo vim /etc/opt/remi/php73/php-fpm.d/www.conf	#for PHP versions 7.0, 7.1,7.3 vvv

You find and uncomment the variable pm.status_path = /status as shown in the screenshot.

[root@DevopsRoles vagrant]# cat /etc/opt/remi/php73/php-fpm.d/www.conf | grep pm.status_path
pm.status_path = /status

Save the changes and exit the file.

Check the PHP-FPM configuration file for any errors

$ sudo php-fpm -t
OR
$ sudo systemctl restart php73-php-fpm

Create a new Nginx config for PHP-FPM as shown

[root@DevopsRoles ~]# vi /etc/nginx/conf.d/php-fpm.conf

# The content as below:

    server {

        listen       80;
        #listen       [::]:80 default_server;
        server_name  127.0.0.1;

    location  /status {
        access_log off;
        allow 127.0.0.1;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_index index.php;
        deny all;
        include fastcgi_params;
        fastcgi_pass 127.0.0.1:9000;
   }
   }

Reload PHP-FPM and Nginx config for changes to take effect.

[root@DevopsRoles ~]# systemctl reload php73-php-fpm
[root@DevopsRoles ~]# systemctl reload nginx

Now, Use the curl command to check php-fpm status.

root@DevopsRoles ~]# curl http://127.0.0.1/status
pool:                 www
process manager:      dynamic
start time:           18/Jul/2020:10:16:17 +0700
start since:          878
accepted conn:        14
listen queue:         0
max listen queue:     0
listen queue len:     128
idle processes:       4
active processes:     1
total processes:      5
max active processes: 1
max children reached: 0
slow requests:        0

Memo: meaning of different values of PHP-FPM Status

-pool – the name of the pool.
-process manager – possible values static, dynamic or ondemand. We never use static.  Trying ondemand is on todo list.
-start time – the date and time FPM has started or reloaded.
-start since – number of seconds since FPM has started
-accepted conn – the number of request accepted by the pool
-listen queue – the number of request in the queue of pending connections. If this number is non-zero, then you better increase number of process FPM can spawn.
-max listen queue – the maximum number of requests in the queue of pending connections since FPM has started
-listen queue len – the size of the socket queue of pending -connections
-idle processes – the number of idle processes
-active processes – the number of active processes
-total processes – the number of idle + active processes
-max active processes – the maximum number of active processes since FPM has started
-max children reached – number of times, the process limit has been reached, when pm tries to start more children. If that value is not zero, then you may need to increase max process limit for your PHP-FPM pool. Like this, you can find other useful information to tweak your pool better way.
-slow requests – Enable php-fpm slow-log before you consider this. If this value is non-zero you may have slow php processes. Poorly written mysql queries are generally culprit.

3. Install Netdata on Centos 7 here

4. Configure Netdata to Monitor PHP-FPM

The Netdata configure for Nginx in folder /etc/netdata/python.d which is written in YAML format.

You can open it or create a new file php-fpm.conf as shown

[root@DevopsRoles python.d]# cat /etc/netdata/python.d/php-fpm.conf 
# The output as below:
localhost:
  name : 'local'
  url  : 'http://localhost/status'

localipv4:
  name : 'local'
  url  : 'http://127.0.0.1/status'

Restart Netdata Server

[root@DevopsRoles ~]# systemctl restart netdata

5. Using Netdata to Monitor PHP-FPM

Open a web browser access the netdata web UI.

http://NETDATA_SERVER_IP:19999
or
http://DOMAIN_NAME:19999

The result as the picture below

Conclusion

Through the article, you can use Netdata to monitor PHP-FPM. I hope will this your helpful. Thank you for reading the DevopsRoles page!

Linux

Using Netdata to Monitor Nginx

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In this tutorial, How to Monitor the Nginx using Netdata on Centos 7. Netdata is a free open source. It is very easy to install and configure for real-time monitoring.

Steps install and configure

  • Centos 7 Server or RHEL 7 Server
  • Install Web Server Nginx
  • Install Netdata and configure Monitor for Web Server Nginx.

1. Install Web Server Nginx

Enable EPEL repository

[root@DevopsRoles ~]# yum install epel-release

Install the Nginx package, as follows.

[root@DevopsRoles ~]# yum install nginx

Start and enable Nginx Web Server, as follows.

[root@DevopsRoles ~]# systemctl start nginx
[root@DevopsRoles ~]# systemctl enable nginx
[root@DevopsRoles ~]# systemctl status nginx

If you are running a firewall. You need to open port 80/443 for Nginx Webserver.

Enable Nginx Stub_Status Module

I will enable the stub_status module which netdata uses to collect metrics from your Nginx web server.

[root@DevopsRoles ~]# vi /etc/nginx/nginx.conf

Copy and paste the location configuration as below

location /server_status {
 	stub_status;
 	allow 127.0.0.1;	#only allow requests from localhost
 	deny all;		#deny all other hosts	
 }

restart the Nginx service to effect

[root@DevopsRoles ~]# nginx -t
[root@DevopsRoles ~]# systemctl restart nginx

Now, Use curl command to check 

curl http://127.0.0.1/server_status

# The output terminal as below:
[root@DevopsRoles ~]# curl http://127.0.0.1/server_status
Active connections: 1 
server accepts handled requests
 1 1 1 
Reading: 0 Writing: 1 Waiting: 0

3. Install Netdata on Centos 7 here

4. Configure Netdata to Monitor Nginx

The Netdata configure for Nginx in folder /etc/netdata/python.d which is written in YAML format.

You can open it or create a new file nginx.conf as below

[root@DevopsRoles python.d]# cat /etc/netdata/python.d/nginx.conf 
# The output as below:
localhost:
  name : 'local'
  url  : 'http://localhost/server_status'

localipv4:
  name : 'local'
  url  : 'http://127.0.0.1/server_status'

Restart Netdata Server

[root@DevopsRoles ~]# systemctl restart netdata

5. Using Netdata to Monitor Nginx Web Server

Open a web browser access the netdata web UI.

http://NETDATA_SERVER_IP:19999
or
http://DOMAIN_NAME:19999

The result as the picture below

Conclusion

Through the article, you can use Netdata to monitor Nginx. I hope will this your helpful. Thank you for reading the DevopsRoles page!

Linux

Using Netdata to Monitor MariaDB Database

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In this tutorial, How to Monitor the MariaDB database using Netdata on Centos 7. Netdata is a free open source. It is very easy to install and configure for real-time monitoring.

Steps install and configure

  • Centos 7 Server or RHEL 7 Server
  • Install MariaDB Database
  • Install Netdata and configure Monitor for MariaDB Database.

1. Install MariaDB Database

Adding MariaDB YUM software repository.

[root@DevopsRoles ~]# vim /etc/yum.repos.d/MariaDB.repo

The content file MariaDB.repo is as follows.

[mariadb]
name = MariaDB
baseurl = http://yum.mariadb.org/10.1/centos7-amd64
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=1

Install the MariaDB package, as follows.

[root@DevopsRoles ~]# yum install MariaDB-server MySQL-python MariaDB-client -y

Start and enable MariaDB Database Server, as follows.

[root@DevopsRoles ~]# systemctl start mariadb
[root@DevopsRoles ~]# systemctl enable mariadb
[root@DevopsRoles ~]# systemctl status mariadb

By default, the MySQL installation is unsecure and you need to secure it, as follows

[root@DevopsRoles ~]# mysql_secure_installation

To create this user MariaDB

MariaDB [(none)]> create user 'netdata'@'localhost'; 
MariaDB [(none)]> grant usage on *.* to 'netdata'@'localhost'; 
MariaDB [(none)]> flush privileges;

If you are running a firewall. You need to open the port 3306 for MariaDB Database

3. Install Netdata on Centos 7 here

4. Configure Netdata to Monitor MariaDB

The netdata configure for MariaDB in folder /etc/netdata/python.d which is written in YAML format.

You can open it or create a new file mysql.conf as below

[root@DevopsRoles python.d]# cat /etc/netdata/python.d/mysql.conf 
localhost:
  name : 'local'
  user : 'netdata'
  port : '3306'

Restart Netdata Server

[root@DevopsRoles ~]# systemctl restart netdata

5. Using Netdata to Monitor MariaDB Database

Open a web browser access the netdata web UI.

http://NETDATA_SERVER_IP:19999
or
http://DOMAIN_NAME:19999

The result as the picture below

Netdata debug for mariadb

/usr/libexec/netdata/plugins.d/python.d.plugin 1 debug mysql

Error netdata for MariaDB code (Fixed)

2020-07-05 16:32:37: python.d ERROR: mysql[localhost] : MySQLdb or PyMySQL module is needed to use mysql.chart.py plugin

On My Centos missing MySQL-python package

Conclusion

Through the article, you can use Netdata to Monitor MariaDB Database. I hope will this your helpful.

Linux

Using Netdata to Monitor Apache Performance

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In this tutorial, How to Monitor Apache Performance using Netdata on Centos 7. Netdata is a free open source. It is very easy to install and configure for real-time monitoring.

Steps install and configure

  • Centos 7 Server or RHEL 7 Server
  • Install Apache HTTP Server with mod_status_module enabled
  • Install Netdata and configure Monitor for Apache HTTP Server.

1. Install Apache HTTP server

First, install the Apache HTTP server on Centos. I will Yum package manager to install Apache.

[root@DevopsRoles ~]# yum install httpd

Start and enable Apache HTTP server.

[root@DevopsRoles ~]# systemctl start httpd
[root@DevopsRoles ~]# systemctl enable httpd
[root@DevopsRoles ~]# systemctl status httpd

If you are running a firewall. You need to open ports 80 and 443 for Apache.

2. Enable mod_status module in Apache

You need to enable and configure the mod_status module in apache, This is required by Netdata.

[root@DevopsRoles ~]# cat /etc/httpd/conf.modules.d/00-base.conf | grep mod_status
LoadModule status_module modules/mod_status.so

Create a server-status.conf for the Apache server-status page as below

[root@DevopsRoles ~]# cat /etc/httpd/conf.d/server-status.conf
<Location "/server-status">
    SetHandler server-status
    #Require host localhost           #uncomment to only allow requests from localhost 
</Location>

Restart Apache HTTP Server

[root@DevopsRoles ~]# systemctl restart httpd

Test working Apache Server status page.

[root@DevopsRoles ~]# curl http://localhost/server-status

3. Install Netdata on Centos 7 here

4. Configure Netdata to Monitor Apache Performance

The Netdata configure for Apache in folder /etc/netdata/python.d

You can open it or create new file apache.conf as below

[root@DevopsRoles ~]# cat /etc/netdata/python.d/apache.conf
localhost:
  name : 'local'
  url  : 'http://localhost/server-status?auto'

localipv4:
  name : 'local'
  url  : 'http://127.0.0.1/server-status?auto'

Restart netdata server

[root@DevopsRoles ~]# systemctl restart netdata

5. Using Netdata to Monitor Apache Performance

Open a web browser access the Netdata web UI.

http://NETDATA_SERVER_IP:19999
or
http://DOMAIN_NAME:19999

The result as below

Conclusion

Thought the article, you can use Netdata to monitor Apache Performance. I hope will this your helpful.

Linux

Mastering the rev command in Linux: Reversing Text Lines

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Introduction

In this guide, we’ll explore how to use the rev command in Linux, a powerful tool for reversing the characters in each line of text. Essential for many DevOps roles, the rev command enhances file manipulation and helps in reversing outputs from other commands. Let’s dive into how this simple yet effective command can streamline your text-processing tasks in Linux environments.

The syntax rev command in Linux

rev [option] [file...]

Some common options for the “rev” command include:

  • -V: Displays the version information for the command.
  • -h: Shows the help information.
  • -c: Treats input as single characters instead of entire lines.

In the manual page, the rev command is described succinctly as a utility to “reverse lines character-wise.” For comprehensive information about the rev command, including its options and examples, refer to the man page by entering man rev in the terminal. This will provide detailed insights into its functionality and usage.

For example rev command

Using the rev command reverses the output of the hostname command as below

[root@ip-10-0-0-236 ~]# hostname
ip-10-0-0-236.us-east-2.compute.internal
[root@ip-10-0-0-236 ~]# hostname | rev
lanretni.etupmoc.2-tsae-su.632-0-0-01-pi
[root@ip-10-0-0-236 ~]#

How to get 8 last characters use the combine rev command and cut command.

[root@ip-10-0-0-236 ~]# hostname
ip-10-0-0-236.us-east-2.compute.internal
[root@ip-10-0-0-236 ~]# hostname | rev | cut -b 1-8 | rev
internal

Sorting File Lines by Last Character

[ec2-user@ip-172-31-45-95 ~]$ cat domain.txt
devopsroles.com
abc.xyz
huuphan.com

[ec2-user@ip-172-31-45-95 ~]$ cat domain.txt  | rev | sort | rev
huuphan.com
devopsroles.com
abc.xyz

Conclusion

Throughout this article, you’ve seen how to utilize the rev command to Reverse characters Linux command. It’s important to remember that the rev command does not alter the original file; it merely displays the reversed output in the terminal or saves it to a new file. I hope you find these examples helpful for mastering the rev command. Thank you for reading at DevopsRoles!

Linux

Linux understand Page cache and buffer cache

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In this tutorial, I have written about Linux understand Page cache and buffer cache in Linux System.

Most file-system cache data read from disk.

Linux understand Page cache

What does Page cache work?

A cache of data is accessed via the file system.

How to check page cache is actually used.

Create a large file

[root@DevopsRoles ~]# mkdir /test
[root@DevopsRoles ~]# dd if=/dev/zero of=/test/large.txt count=100 bs=10M
100+0 records in
100+0 records out
1048576000 bytes (1.0 GB) copied, 1.62731 s, 644 MB/s
[root@DevopsRoles ~]# echo 3 > /proc/sys/vm/drop_caches

Check memory usage before putting it in the page cache

[root@DevopsRoles ~]# vmstat
 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
  1  0      0 377344      0  64336    0    0   441  5203  131  293  0  2 97  0  0

[root@DevopsRoles ~]# cat /test/large.txt > /dev/null

Check memory usage after getting on page cache

[root@DevopsRoles ~]# vmstat 
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 2  0      0   6500      0 435008    0    0  3265  3008  108  179  0  2 98  0  0

We will confirm that accessing data in the cache is fast.

Run command 1s

[root@DevopsRoles ~]# time cat /test/large.txt > /dev/null

real	0m1.068s
user	0m0.003s
sys	0m0.987s

Run command 2s

[root@DevopsRoles ~]# time cat /test/large.txt > /dev/null

real	0m1.064s
user	0m0.003s
sys	0m0.981s

Linux understand buffer cache

What does Buffer cache work?

Cache data accessed via raw I/O. It is a page cache for block devices.

How to check Buffer cache is actually used.

[root@DevopsRoles ~]# vmstat
 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
  1  0      0   5668      0 435832    0    0  6434  2087  116  132  0  2 98  0  0
 [root@DevopsRoles ~]# dd if=/dev/sda of=/dev/null count=100 bs=10M
 100+0 records in
 100+0 records out
 1048576000 bytes (1.0 GB) copied, 1.59043 s, 659 MB/s

Increase buffer cache (buff)

We will confirm that accessing data in the cache is fast.

Run command 1s

[root@DevopsRoles ~]# vmstat
 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
  2  0      0  13408 359528  68520    0    0  7715  1888  123  127  0  2 98  0  0
 [root@DevopsRoles ~]# time dd if=/dev/sda of=/dev/null count=100 bs=10M
 100+0 records in
 100+0 records out
 1048576000 bytes (1.0 GB) copied, 1.13208 s, 926 MB/s
 real    0m1.138s
 user    0m0.001s
 sys    0m1.068s

Run command 2s

[root@DevopsRoles ~]# vmstat
 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
  2  0      0  13664 359220  68520    0    0  8896  1747  130  119  0  2 98  0  0
 [root@DevopsRoles ~]# time dd if=/dev/sda of=/dev/null count=100 bs=10M
 100+0 records in
 100+0 records out
 1048576000 bytes (1.0 GB) copied, 1.13821 s, 921 MB/s
 real    0m1.144s
 user    0m0.001s
 sys    0m1.072s

Conclusion

Linux understand Page cache and buffer cache. I hope will this your helpful. Thank you for reading the DevopsRoles page!

Database Administrator

Setting Up Oracle Automatic Startup on Linux: A Comprehensive Guide

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Introduction

In this tutorial, How to confirm Oracle automatic startup on Linux. How to make Oracle start automatically in Linux.

Ensuring that your Oracle database starts automatically when your Linux system boots up can save time and reduce manual intervention, enhancing the reliability of your database operations.

This guide will walk you through the process of configuring automatic startup for Oracle on a Linux system. By following these steps, you can ensure that your Oracle database is always ready to handle your data needs, even after a system reboot.

By default, Oracle software installation does not deploy automatic startup and shutdown init scripts on the platform.

How to confirm Oracle automatic startup on Linux.

The dbstart utility reads the oratab file. Confirm it in the example below

[HuuPV@DevopsRoles ~]$ sudo su - oracle
[oracle@DevopsRoles ~]$ cat /etc/oratab

 DEVOPSROLES_SID:/opt/oracle/product/11.2.0/dbhome_1:Y 
 DEVOPSROLES_SID02:/opt/oracle/product/10.2.03/dbhome_2:N

We see there are two instances on this server. Oracle 10.2.03 is marked “N” and will not restart when the Linux OS reboots. Oracle 11.2.0 is marked “Y” and will restart when the Linux OS reboots.

Auto Start Oracle on Linux

1. In the /etc/oratab file with the autostart column to “Y”

[oracle@DevopsRoles ~]$ cat /etc/oratab
DEVOPSROLES_SID:/opt/oracle/product/11.2.0/dbhome_1:Y

2. Create the file named “oracle” in /etc/init.d folder.

[root@DevopsRoles ~]# cd /etc/init.d
[root@DevopsRoles init.d]# vi oracle

#!/bin/sh
ORACLE_HOME=/opt/oracle/product/11.2.0/dbhome_1
ORACLE_OWNER=oracle
case "$1" in
'start') # Start the Oracle databases and listeners
su - $ORACLE_OWNER -c "$ORACLE_HOME/bin/dbstart $ORACLE_HOME"
;;
'stop') # Stop the Oracle databases and listeners
su - $ORACLE_OWNER -c "$ORACLE_HOME/bin/dbshut $ORACLE_HOME"
;;
esac

3. Create a symbolic link

[root@DevopsRoles ~]# ln -s /etc/init.d/oracle /etc/rc0.d/K10oracle
[root@DevopsRoles ~]# ln -s /etc/init.d/oracle /etc/rc3.d/S99oracle

4. Change permissions

[root@DevopsRoles ~]# chmod 750 /etc/init.d/oracle

5. use chkconfig the command to associate the dbora service

[root@DevopsRoles ~]# chkconfig --level 2345 oracle on

Test

restart the Oracle server. Then check the instance status

[oracle@DevopsRoles ~]$ ps -ef | grep smon | grep -v grep

Check the listener status

[oracle@DevopsRoles ~]$ lsnrctl status

Conclusion

Configuring Oracle for automatic startup on Linux significantly improves the efficiency and reliability of your database management. By following the steps outlined in this guide, you have learned how to set up your Oracle database to start automatically with your Linux system, ensuring minimal downtime and maximum productivity. Regular maintenance and monitoring will further ensure the smooth operation of your database. Keep exploring and optimizing your setup to make the most out of your Oracle database. Thank you for reading DevOpsRoles.com page

Linux

nl command in Linux with example

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Introduction

In this tutorial, we will explore how to use the nl command in Linux to number lines of files. The nl command is a powerful tool for adding line numbers to the contents of a file or standard input. This can be incredibly useful for referencing specific lines more easily or for organizing and presenting content more clearly. Let’s delve into practical examples to demonstrate how the nl command can be effectively utilized in various scenarios.

What does the nl command mean?

The nl command stands for “number lines,” and it is used in Linux to add line numbers to the contents of files or standard input. This functionality is particularly useful for referencing specific lines more easily in scripts or documents.

nl command syntax

nl [OPTION]… [FILE]…

Some common options for the “nl” command include:

  • -b <type>: Specifies the numbering style. The <type> can be a (all lines), t (non-empty lines), or n (no lines).
  • -i <increment>: Sets the line number increment. The <increment> can be any positive integer.
  • -v <number>: Sets the starting line number. The <number> can be any positive integer.
  • -w <width>: Specifies the field width for line numbers.

On the man page, the describes it

  • nl – number lines of files.
  • man nl – More details information about nl command.

nl command in Linux with an example

I have created a file nl_command.txt as below

[vagrant@DevopsRoles ~]$ cat nl_command.txt                                    
 HuuPV, My website DevopsRoles.com and HuuPhan.com.SN:199x.
 Devops Roles.
 Devops Roles.
 Devops Roles.
 Devops Roles.
 Hello world :)

By default, the nl command doesn’t number empty lines

[vagrant@DevopsRoles ~]$ nl nl_command.txt 
      1  HuuPV, My website DevopsRoles.com and HuuPhan.com.SN:199x.
      2  Devops Roles.
      3  Devops Roles.
      4  Devops Roles.
      5  Devops Roles.
      6  Hello world :)

How to number empty lines.

[vagrant@DevopsRoles ~]$ nl -b a nl_command.txt                                
      1  HuuPV, My website DevopsRoles.com and HuuPhan.com.SN:199x.
      2  Devops Roles.
      3  Devops Roles.
      4  Devops Roles.
      5  Devops Roles.
      6  
      7  Hello world :)

How to numbering formats

[vagrant@DevopsRoles ~]$ nl -n ln nl_command.txt                               
 1       HuuPV, My website DevopsRoles.com and HuuPhan.com.SN:199x.
 2       Devops Roles.
 3       Devops Roles.
 4       Devops Roles.
 5       Devops Roles.
 6       Hello world :)
 [vagrant@DevopsRoles ~]$ nl -n rz nl_command.txt 
 000001  HuuPV, My website DevopsRoles.com and HuuPhan.com.SN:199x.
 000002  Devops Roles.
 000003  Devops Roles.
 000004  Devops Roles.
 000005  Devops Roles.
 000006  Hello world :)

Customized numbering separator

[vagrant@DevopsRoles ~]$ nl nl_command.txt                                     
      1  HuuPV, My website DevopsRoles.com and HuuPhan.com.SN:199x.
      2  Devops Roles.
      3  Devops Roles.
      4  Devops Roles.
      5  Devops Roles.
      6  Hello world :)
 [vagrant@DevopsRoles ~]$ nl -s : nl_command.txt 
      1:HuuPV, My website DevopsRoles.com and HuuPhan.com.SN:199x.
      2:Devops Roles.
      3:Devops Roles.
      4:Devops Roles.
      5:Devops Roles.
      6:Hello world :)

Conclusion

nl command is a simple command in Linux. It uses the number of lines of files. You can refer to the manual page for the “nl” command by typing man nl in the terminal for more information and additional options available on your specific Linux distribution. Thank you for reading the DevopsRoles page!