Similar Posts
HDFS stays in safe mode because of reported blocks not reaching 0.9990 of total blocks
ByEric MaAfter a node failure and restarting the HDFS, the NameNode reports: “The reported blocks 1968810 needs additional 5071 blocks to reach the threshold 0.9990 of total blocks 1975856. Safe mode will be turned off automatically.” in the log. Why this happens? And how to fix it? About why the NameNode stays in the safe mode:…
How to print out text with line numbers in Linux
ByEric MaHow to print out a plain text file with line numbers in Linux? Use the nl command: nl text-file Find options in the nl manual. Read more: How to add a space between the line numbers and text content in Emacs? Deleting a Specific Line From a Text File in Command Line in Linux How…
How to run screen on a Linux host reporting “Cannot make directory ‘/var/run/screen’: Permission denied”?
ByEric MaI want to run screen on a remote host on which I do not have root/sudo privilege and screen is not installed. I can compile or copy the screen program that can run on the host. However, it reports: “Cannot make directory ‘/var/run/screen’: Permission denied” As screen is not installed on the host, the directory…
Sending emails securely
ByQ ASending emails securely is needed for certain situations, such as sending my bank account to my wife, giving my account password to my close friend for a while. How to send it? Regarding the recent US PRISM program, it is an important issue. Seeing your solution, a few of my own popped up. Here are…
How to get an environment variable in Go?
ByQ AIn Go lang, how to get an environment variable? To get an environment variable (e.g. “VAR”) in GO: import “os” import “fmt” fmt.Println(“VAR:”, os.Getenv(“VAR”)) Read more: How to get an environment variable in Python? How to set and get an environment variable in C on Linux? How to get an environment variable in Python? How…
- Blockchain | Systems | Systems 101 | Tutorial
Proof of Ownership for BTC Addresses: A Detailed Guide
ByEric MaProving ownership of a Bitcoin (BTC) address is a crucial aspect in various scenarios, such as verifying identity in a transaction or demonstrating holdings without revealing private keys. This guide explores how to prove ownership for different BTC address types, including algorithm specifications and step-by-step methods. BTC Address Types P2PKH (Pay-to-Public-Key-Hash) P2SH (Pay-to-Script-Hash) P2WPKH (Pay-to-Witness-Public-Key-Hash)…