The sed command is a stream editor for filtering and transforming text. In this tutorial, How to sed command in Linux with Examples.

The sed command-Line in Linux, which stands for “stream editor,” is a powerful text processing tool used for performing various text manipulations and transformations. It reads input line by line, applies specified operations, and outputs the result. Here are a few examples of how to use the sed command line:

Syntax

sed [OPTION]... {script-only-if-no-other-script} [input-file]...

On the man page, the describes it

• sed – modifies lines from the specified File parameter according to an edit script and writes them to standard output.
• man sed – More details information about the sed command.

The sed command in Linux with Examples

For example, the file sed_test.txt as below

[huupv@DevopsRoles vagrant]$ cat sed_test.txt                                                                                                                                  
# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help

driftfile /var/lib/ntp/ntp.drift

# Enable this if you want statistics to be logged.
#statsdir /var/log/ntpstats/

statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable

# Specify one or more NTP servers.

# Use servers from the NTP Pool Project. Approved by Ubuntu Technical Board
# on 2011-02-08 (LP: #104525). See http://www.pool.ntp.org/join.html for
# more information.
pool 0.ubuntu.pool.ntp.org iburst
pool 1.ubuntu.pool.ntp.org iburst
pool 2.ubuntu.pool.ntp.org iburst
pool 3.ubuntu.pool.ntp.org iburst

Append line

$ sed '/^pool 3/ a server ntp.devopsroes.com' sed_test.txt

Insert line

It will be added lines before the matching line.

$ sed '/^pool 3/i server ntp.devopsroles.com' sed_test.txt

Delete line

used d to delete matching lines. \s is escaped for regular expressions.

$ sed ' /^pool\s[0-9]\.ubuntu/d' sed_test.txt

How to write multi-line

There are two ways, use {} or other files.

Use {}

$ sed ' {
 /^pool 0/i server ntp.devopsroles.com
 /^pool\s[0-9]/d
 } ' ./sed_test.txt

create a ntp.sed file and read with the -f option.

The content ntp.sed file.

/^$/d
/^\s*#/d
/^pool 0/ i server ntp.devopsroles.com prefer
/^pool\s[0-9]\.ubuntu/d

Explain the above line.

/^$/d - Delete blank lines.
/^\s*#/d - Delete the line following # after any space including 0 (Delete comment line of #)

As a result

$ sed -f ntp.sed sed_test.txt

The backup file before changing the original file has been modified.

$ sed -i.bak -f ntp.sed ntp.conf

Print specific lines from a file

sed -n '2,5p' input_file

Delete lines matching a pattern

sed '/pattern/d' input_file

Append text after a specific line

sed '/pattern/a\new_line' input_file

Conclusion

sed Linux is a simple command in Linux. It uses the number of lines of files. These are just a few examples of how to use the sed command in Linux.

The sed command offers a wide range of text manipulation capabilities, including search and replace, insertions, deletions, and more. Thank you for reading the DevopsRoles page!

Introduction

In today’s DevOps-driven world, Kubernetes has become an essential tool for managing containerized applications at scale. However, setting up a full Kubernetes cluster can be complex and resource-intensive. How to Minikube Build local Kubernetes.

Minikube is a lightweight Kubernetes implementation that creates a local, single-node Kubernetes cluster for development and testing. In this guide, we’ll walk you through everything you need to know to build a local Kubernetes environment using Minikube, from basic setup to advanced configurations. In this tutorial, How to use Minikube Build local Kubernetes environment.

Why Use Minikube?

• Ease of Use: Minikube simplifies the process of setting up a Kubernetes cluster.
• Local Development: Ideal for local development and testing.
• Resource Efficient: Requires fewer resources compared to a full-scale Kubernetes cluster.
• Feature-Rich: Supports most Kubernetes features and add-ons.

Prerequisites

Before you start, ensure you have the following:

• A computer with at least 2GB of RAM and 20GB of free disk space.
• A hypervisor like VirtualBox, VMware, Hyper-V, or KVM.
• kubectl, the Kubernetes command-line tool, was installed.
• Minikube installed.

My Virtual Machine has installed Docker. Reference: Link here

Minikube Build local Kubernetes

Install Minikube and kubectl

Minikube

$ curl -Lo minikube https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64 && chmod +x minikube && sudo mv minikube /usr/local/bin/

kubectl

$ curl -Lo kubectl https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl && chmod +x kubectl && sudo mv kubectl /usr/local/bin/

Set of environment variables.

$ sudo vi /etc/profile

#Add end line in file
export MINIKUBE_WANTUPDATENOTIFICATION=false
export MINIKUBE_WANTREPORTERRORPROMPT=false
export MINIKUBE_HOME=/root
export CHANGE_MINIKUBE_NONE_USER=true
export KUBECONFIG=/root/.kube/config

$ sudo mkdir -p /root/.kube || true
$ sudo touch /root/.kube/config

Launch Minikube

You can use used "--vm-driver=none" option to build Kubernetes on the host running Minikube

$ sudo /usr/local/bin/minikube start --vm-driver=none

File /root/.kube/config have been created. verify the content

$ sudo kubectl config view

Check service minikube status

$ sudo minikube status

Allow port 8443 on the firewall

$ sudo firewall-cmd --add-port=8443/tcp --zone=public --permanent
$ sudo firewall-cmd --reload
$ sudo firewall-cmd --list-all

Create and start container dashboard

using image “k8s.gcr.io/echoserver:1.4” to create the dashboard

$ sudo docker images | grep 'k8s.gcr.io/echoserver'

Minikube created a pod

$ sudo kubectl run hello-minikube --image=k8s.gcr.io/echoserver:1.4 --port=808

To verify node and pod

$ sudo kubectl get nodes
$ sudo kubectl get pods

Instances run on nodes as Docker containers. Displays a list of deployments.

$ sudo kubectl get deployments

Creating service

You use "--type=NodePort" option. Open the service on the IP of each node to the static port (NordPort). A ClusterIP Service routed by the NodePort Service is automatically created. You can access the NordPort Service from outside the cluster by requesting :

$ sudo kubectl expose deployment hello-minikube --type=NodePort
$ sudo kubectl get services

Access dashboard

Get the dashboard URL. The port automatically changes one time.

$ sudo minikube dashboard --url
$ curl http://127.0.0.1:36439/api/v1/namespaces/kube-system/services/http:kubernetes-dashboard:/proxy/

When accessing via Kubernetes proxy

kubectl acts as a reverse proxy to the API endpoint.

$ sudo minikube dashboard --url
$ sudo kubectl proxy
$ curl http://localhost:8001

Accessible dashboard from outside

Minikube started with the "--vm-driver=none" option, it can only be accessed from the host OS using the proxy. Therefore, change the proxy settings so that they can be accessed from outside the host OS (browser).

$ sudo minikube dashboard --url
$ sudo kubectl proxy --address=0.0.0.0 --accept-hosts='.*'

Link URL: http://{YOUR_HOST_NAME}:8001/api/v1/namespaces/kube-system/services/http:kubernetes-dashboard:/proxy/#!/overview?namespace=default

The verify log

$ sudo kubectl logs hello-minikube-78c9fc5f89-9whkn
$ minikube logs -f 

Using kubectl command to delete service, deployment

$ sudo kubectl delete services hello-minikube
$ sudo kubectl delete deployment hello-minikube

Get status to have delete service, deployment

$ sudo kubectl get nodes
$ sudo kubectl get pods
$ sudo kubectl get services
$ sudo kubectl get deployments

Stop minikube and delete the cluster

$ sudo minikube stop
$ minikube delete

Conclusion

Minikube is an excellent tool for developers who want to learn and experiment with Kubernetes without the complexity of setting up a full-scale cluster. By following this guide, you can easily set up a local Kubernetes environment using Minikube, deploy applications, and explore advanced features. Whether you’re a beginner or an experienced developer, Minikube provides a convenient and efficient way to work with Kubernetes on your local machine.

In this tutorial, How to install Minikube kubernetes to configure a single Node Cluster within a VM. How do I Configure Kubernetes which is a Docker Container system?

A Hypervisor supported by Minikube. In this example, Install KVM Hypervisor. You can use other Hypervisors such as VirtualBox, VMware Fusion v.v.

Install Minikube kubernetes

KVM Hypervisor installing

[root@DevopsRoles ~]# yum -y install qemu-kvm libvirt libvirt-python libguestfs-tools virt-install libvirt-daemon-kvm
[root@DevopsRoles ~]# systemctl start libvirtd
[root@DevopsRoles ~]# systemctl enable libvirtd

Add repository for configure Kubernetes and Install Minikube

Configure Kubernetes repository

[root@DevopsRoles ~]# cat <<'EOF' > /etc/yum.repos.d/kubernetes.repo

[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-$basearch
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
EOF

Install Minikube

[root@DevopsRoles ~]# yum -y install kubectl
[root@DevopsRoles ~]# wget https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64 -O minikube
[root@DevopsRoles ~]# wget https://storage.googleapis.com/minikube/releases/latest/docker-machine-driver-kvm2
[root@DevopsRoles ~]# chmod 755 minikube docker-machine-driver-kvm2
[root@DevopsRoles ~]# mv minikube docker-machine-driver-kvm2 /usr/local/bin/

Check version minikube

[root@DevopsRoles ~]# /usr/local/bin/minikube version
[root@DevopsRoles ~]# kubectl version -o json 

Start Minikube

[root@DevopsRoles ~]# minikube start --vm-driver kvm2 

Minikube the command line

#show status
[root@DevopsRoles ~]# minikube status
[root@DevopsRoles ~]# minikube service list 
[root@DevopsRoles ~]# minikube docker-env 
[root@DevopsRoles ~]# kubectl cluster-info 
[root@DevopsRoles ~]# kubectl get nodes 
[root@DevopsRoles ~]# virsh list
[root@DevopsRoles ~]# minikube ssh # possible to access with SSH to the VM
[root@DevopsRoles ~]# minikube stop # to stop minikube, do like follows
[root@DevopsRoles ~]# minikube delete  # to remove minikube, do like follows
[root@DevopsRoles ~]# virsh list --all 

Conclusion

Thought the article, How to install “Minikube Kubernetes on Centos” as above. I hope will this your helpful. Thank you for reading the DevopsRoles page!