Table of contents
Concept: What’s the CIDR(Classless Inter-Domain Routing)
From the Google Search:
CIDR notation is a compact way to express an IP address and its associated network by following it with a slash and a number indicating how many bits are used for the network prefix
The format is IP_ADDRESS/PREFIX_LENGTH.
For example, in 192.168.1.0/24, 192.168.1.0 is the IP address, and /24 is the prefix length.
The IP Address is 32 bits. There are four parts seperated by dot(.) and each part has 8 bits. So each part has 2**8=256 different numbers. As it starts from 0, so the range is 0- 255.
For example, 10.0.0.0/16 represents all IP addresses in 10.0.0.0 and 10.0.255.255. Why? 32 bits - 16 bits = 16 bits, so the first two parts (2*8 = 16) is prefix address. the left two parts can be used for the subnet address. so the IP addresses can be used from 10.0.0.0 to 10.0.255.255.
If the subnet is 10.0.0.0/24, then all IP addresses is in 10.0.0.0 and 10.0.0.255. Because only 8 bits left for the subnet.
AWS CLI to restore an Amazon S3 object from the S3 Glacier Flexible Retrieval or S3 Glacier Deep Archive storage class
$ aws s3api restore-object --bucket awsexamplebucket --key dir1/example.obj --restore-request '{"Days":25,"GlacierJobParameters":{"Tier":"Standard"}}'
Copy local file to AWS S3
When you transfer data to AWS S3, you need to use the following code
aws s3 cp "${pathLocalFile}" s3://"$bucketName/$bucketFolder/" --sse AES256 --no-progress
Here you need to pay attention to the following stuff:
- you need to add backslash at the end of the bucket folder or backet name
/. So the command line know it’s a folder and save the local file to the folder, otherwise it will be treated as a file name that you want to name the local file in the AWS S3 - it’s safe to use double quote
"to enclose the variable when using the command line in case the path of varialbe contains empty space which will make the command line volid