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Blockchain | Systems | Systems 101 | Tutorial
Proof of Ownership for BTC Addresses: A Detailed Guide
ByEric Ma
Proving 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)…
How to make the video play in background in iPhone?
ByQ A
Each time I play a video and lock the iPhone by pushing the power button, the video is automatically stopped. If I want to play a MTV and just listen to the music when I walking, I’d like the video play in the background. Is there a method to make this happen? I can do…
How to change number of replications of certain files in HDFS?
ByEric Ma
The HDFS has a configuration in hdfs-site.xml to set the global replication number of blocks with the “dfs.replication” property. However, there are some “hot” files that are access by many nodes. How to increase the number of blocks for these certain files in HDFS? You can the replication number of certain file to 10: hdfs…
Additional Repositories for Fedora Linux
ByEric Ma
Fedora’s repositories provide most of the software packages needed when using Linux. However, for various consideration, they do not provide some packages, such as MPlayer, ffmpeg. Fortunately, some community maintained repository provides these software. And they may also package propriety software, such as ATI fglrx dive, NVIDIA driver, into rpm packages. In this post, we…
How to allow contributors to Upload Files in wordpress
ByEric Ma
How to allow contributors to Upload Files in wordpress? I allow my wordpress site’s contributors to submit posts. But by default, WordPress contributors do not have the capability to upload files. How to allow them to upload files? The key to my solution to add the upload files capability to contributors in WordPress is the…
Maximum number of mmap()’ed ranges and how to set it on Linux?
ByEric Ma
What’s the maximum number of mmap()‘ed ranges that a process can makes and how to set the limits on Linux? I have a program that mmap()s and mprotect()s lots ranges. After allocating many ranges, mprotect() starts to fail with ENOMEM error number. From the man page, ENOMEM means 2 possible problems: ENOMEM Internal kernel structures…