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Linux Operations Skills ​

Supported Versions: All major Linux distributions Last Updated: February 11, 2026

This document covers essential Linux operations skills for working effectively in Kubernetes environments.

Table of Contents ​

  1. Environment Variables and Shell Configuration
  2. Shell Scripting Basics
  3. Text Processing Tools
  4. SSH and Remote Access
  5. Performance Monitoring and Troubleshooting
  6. Storage Management Basics
  7. curl and API Calls
  8. Practical One-Liners Collection

1. Environment Variables and Shell Configuration ​

Environment variables are the core mechanism for managing configuration in Linux and Kubernetes.

1.1 Environment Variable Basics ​

bash
env
echo $HOME
echo $PATH
printenv HOME

1.2 The export Command ​

bash
export MY_VAR="hello"
export DATABASE_URL="postgresql://localhost:5432/mydb"
export KUBECONFIG="/home/user/.kube/config"

1.3 The source Command ​

bash
cat > ~/my-env.sh << 'SCRIPT'
export APP_ENV="production"
export APP_PORT="8080"
alias k='kubectl'
SCRIPT

source ~/my-env.sh

1.4 .bashrc and .bash_profile ​

bash
cat >> ~/.bashrc << 'SCRIPT'
export KUBECONFIG=~/.kube/config
source <(kubectl completion bash)
alias k='kubectl'
SCRIPT

source ~/.bashrc

1.5 Kubernetes ConfigMap Connection ​

yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  DATABASE_HOST: "mysql.default.svc.cluster.local"
  DATABASE_PORT: "3306"
---
apiVersion: v1
kind: Pod
metadata:
  name: app-pod
spec:
  containers:
  - name: app
    image: myapp:1.0
    envFrom:
    - configMapRef:
        name: app-config

2. Shell Scripting Basics ​

2.1 Variables ​

bash
#!/bin/bash
NAME="kubernetes"
NAMESPACE=${1:-default}
: ${REQUIRED_VAR:?"REQUIRED_VAR must be set"}

2.2 Conditionals ​

bash
if [ "$ENV" = "production" ]; then
    echo "Production mode"
fi

case "$1" in
    start) echo "Starting..." ;;
    stop) echo "Stopping..." ;;
esac

2.3 Loops ​

bash
for ns in default kube-system monitoring; do
    kubectl get pods -n "$ns"
done

while true; do
    STATUS=$(kubectl get pod mypod -o jsonpath='{.status.phase}')
    [ "$STATUS" = "Running" ] && break
    sleep 5
done

2.4 Functions ​

bash
check_pod_exists() {
    local pod_name=$1
    kubectl get pod "$pod_name" &>/dev/null
}

2.5 Init Container Patterns ​

yaml
apiVersion: v1
kind: Pod
metadata:
  name: app-with-init
spec:
  initContainers:
  - name: wait-for-db
    image: busybox:1.35
    command: ['sh', '-c', 'until nc -z mysql 3306; do sleep 2; done']
  containers:
  - name: app
    image: myapp:1.0

3. Text Processing Tools ​

3.1 grep with kubectl ​

bash
kubectl get pods | grep -v "Running"
kubectl logs nginx-pod | grep -i error

3.2 awk Field Extraction ​

bash
kubectl get pods | awk 'NR>1 {print $1}'
kubectl get pods | awk '$3 != "Running" {print $1, $3}'

3.3 sed Editing ​

bash
sed -i 's/replicas: [0-9]*/replicas: 5/' deployment.yaml

3.4 JSON Parsing with jq ​

bash
kubectl get pod nginx -o json | jq '.metadata.name'
kubectl get pods -o json | jq -r '.items[].metadata.name'

3.5 YAML Parsing with yq ​

bash
yq '.metadata.name' deployment.yaml
yq -i '.spec.replicas = 5' deployment.yaml

4. SSH and Remote Access ​

4.1 SSH Key Generation ​

bash
ssh-keygen -t ed25519 -C "your_email@example.com"

4.2 SSH Tunneling ​

bash
ssh -L 8080:localhost:80 user@server
ssh -L 6443:kubernetes-api:6443 user@bastion

4.3 Bastion Host Usage ​

bash
ssh -J bastion user@internal-server

4.4 rsync ​

bash
rsync -avzP ./local/ user@remote:/path/

5. Performance Monitoring and Troubleshooting ​

5.1 top and htop ​

bash
top -b -n 1 | head -20

5.2 vmstat and iostat ​

bash
vmstat 1 5
iostat -dx 1 5

5.3 free and df ​

bash
free -h
df -h

5.4 kubectl top ​

bash
kubectl top nodes
kubectl top pods --sort-by=memory

6. Storage Management Basics ​

6.1 lsblk ​

bash
lsblk -f

6.2 LVM ​

bash
sudo pvcreate /dev/nvme1n1
sudo vgcreate data_vg /dev/nvme1n1
sudo lvcreate -l 100%FREE -n data_lv data_vg

6.3 Kubernetes PV/PVC ​

yaml
apiVersion: v1
kind: PersistentVolume
metadata:
  name: local-pv
spec:
  capacity:
    storage: 100Gi
  accessModes: [ReadWriteOnce]
  storageClassName: local-storage
  local:
    path: /mnt/disks/vol1

7. curl and API Calls ​

7.1 HTTP Methods ​

bash
curl -X POST -H "Content-Type: application/json" -d '{"name":"John"}' https://api.example.com/users

7.2 Kubernetes API Calls ​

bash
TOKEN=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token)
curl -s --cacert $CACERT -H "Authorization: Bearer $TOKEN" \
  "https://kubernetes.default.svc/api/v1/namespaces/default/pods"

7.3 Useful curl Options ​

bash
curl -s -o /dev/null -w "%{http_code}" https://api.example.com/health

8. Practical One-Liners Collection ​

8.1 Kubernetes Operations ​

bash
kubectl get pods -A | awk '$4 != "Running" && NR>1 {print $1, $2, $4}'
kubectl get pods -A -o json | jq -r '.items[] | select(.status.containerStatuses[]?.restartCount > 5) | .metadata.name'

8.2 Log Analysis ​

bash
kubectl logs deploy/app --since=1h | grep -i error

8.3 Network Debugging ​

bash
nslookup kubernetes.default.svc.cluster.local
nc -zv service-name 80

Conclusion ​

  1. Environment Variables: Foundation for K8s ConfigMap/Secret
  2. Shell Scripting: Essential for init containers, health checks
  3. Text Processing: Core to kubectl output parsing
  4. SSH: Important for node debugging
  5. Performance Monitoring: Foundation of troubleshooting

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