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Log rotation demo with Systemd Unit

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System Units To demonstrate log rotation using logrotate and helps to understand systemD unit creation and apply compute resoruce(memory/CPU) to specific cgroup. Create script that generates logs /home/scripts/script_logrotate.sh #!/bin/bash # https://redis.io/docs/latest/develop/use/patterns/bulk-loading/ # Set the number of keys to generate num_keys=2000 # Set the size of the value for each key (in bytes) # 1MB , with k and v, -> 2MB value_size=64 # create logs dir mkdir -p /home/scripts/logs/ # Set the output file name output_file="/home/scripts/logs/redis-data.log" # Generate data and write to file for i in $(seq 1 $num_keys); do # Generate a random string of the specified size value=$(head -c $value_size /dev/urandom | tr -dc A-Za-z0-9 | head -c $value_size) # Create the Redis SET command redis_command1="SET key$i \"$value\"" # Append the command to the output file echo "$redis_command1" ...
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Network Subnet Calculator

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Network Subnet Calculator Network Subnet Calculator A subnet is a division of an IP network (internet protocol suite), where an IP network is a set of communications protocols used on the Internet and other similar networks. It is commonly known as TCP/IP (Transmission Control Protocol/Internet Protocol). The act of dividing a network into at least two separate networks is called subnetting, and routers are devices that allow traffic exchange between subnetworks, serving as a physical boundary. IPv4 is the most common network addressing architecture used, though the use of IPv6 has been growing since 2006. How to calculator subnet CIDR Block in java Below simple algorithm calculates required cidr block Using master CIDR Block. CidrBlockBuilderTest.java package cidr; import org.junit.jupiter.api.Assertions; import org.junit.jupiter.api.Test; import java.util.Iterator; /** * @author tvajjala */ public class CidrBlockBuilderTest { @Test ...
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Java Cryptography

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Java Cryptographic Architecture Table of Contents Java Cryptographic Architecture Provider Architecture Random Number Generation Key Management Message Digests Encryption Algorithms & Cipher Popular Providers Public Key Infrastructure(PKI) FIPS 140-2 Java Cryptographic Architecture Java cryptography software comes in two sections. JCA The overall design of the cryptography classes is governed by the java cryptography architecture(JCA). The JCA specify design patterns and extensible architecture for defining cryptographic concepts and algorithms. These concepts(interfaces) are encapsulated by java.security and javax.crypto packages. Implementation ares supplied by cryptographic providers. JDK1.2 comes with a default provider, named SUN . which implements a few cryptographic algorithms. JCE Java split its cryptography classes into two groups. First group is included in the java.security.* packages that are part of ...
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