niepiekm

Hyperlinks (a.k.a. HTML-like anchors) in terminal emulators

[ Update 2020-05-31: I won't be maintaining this page or responding to comments anymore (except for perhaps a few exceptional occasions). ]

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Most of the terminal emulators auto-detect when a URL appears onscreen and allow to conveniently open them (e.g. via Ctrl+click or Cmd+click, or the right click menu).

It was, however, not possible until now for arbitrary text to point to URLs, just as on webpages.

niepiekm

Let's Destroy C

I have a pet project I work on, every now and then. CNoEvil.

The concept is simple enough.

What if, for a moment, we forgot all the rules we know. That we ignore every good idea, and accept all the terrible ones. That nothing is off limits. Can we turn C into a new language? Can we do what Lisp and Forth let the over-eager programmer do, but in C?

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niepiekm

#include <iostream>
#include <unordered_map>
#include <list>
#include <stdexcept>

template <typename K, typename V>
class lru_cache {
private:
	typedef std::pair<K, V> cache_entry;
	typedef std::list<cache_entry> cache_list;

niepiekm

CFLAGS = -std=c99 -Wall

main : main.o

.PHONY : test clean

test : main
	./$^ "*regex*" "*vtable*" < main.c

clean :

niepiekm

Check that your system supports systemd

pidof systemd
2733

If this return a number then your system supports systemd. Most Linux distributions in 2017 support systemd.

Check out the proceses currently running.

Since systemd starts the process then all processes will be children of systemd

niepiekm

High-Performance Matrix Multiplication

This is a short post that explains how to write a high-performance matrix multiplication program on modern processors. In this tutorial I will use a single core of the Skylake-client CPU with AVX2, but the principles in this post also apply to other processors with different instruction sets (such as AVX512).

Intro

Matrix multiplication is a mathematical operation that defines the product of

niepiekm

Anti-tests

The requirement

Let's say we've been tasked with returning 400 when GET /users/<userId> is called with a negative userId.

The test

The requirement can be turned into a test that hits the endpoint with a negative userId and checks that a 400 is returned:

    @Test
    public void getUser_InvalidUserId_400() {

niepiekm

# source: http://st-on-it.blogspot.com/2010/01/how-to-move-folders-between-git.html
# First of all you need to have a clean clone of the source repository so we didn't screw the things up.

git clone git://server.com/my-repo1.git

# After that you need to do some preparations on the source repository, nuking all the entries except the folder you need to move. Use the following command

git filter-branch --subdirectory-filter your_dir -- -- all

# This will nuke all the other entries and their history, creating a clean git repository that contains only data and history from the directory you need. If you need to move several folders, you have to collect them in a single directory using the git mv command.

niepiekm

# copied from http://gbayer.com/development/moving-files-from-one-git-repository-to-another-preserving-history/
git clone <git repository A url> # clone source repository
cd <git repository A directory>
git remote rm origin # to make sure it doesn't affect the original repository
git filter-branch --subdirectory-filter <directory 1> -- --all # remove all files other than the ones needed
mkdir <directory 1> # move them into another directory where they will be stored in the destination repository (if needed)
mv * <directory 1>
git add .
git commit

niepiekm

## within current branch, squashes all commits that are ahead of master down into one
## useful if you merged with upstream in the middle of your commits (rebase could get very ugly if this is the case)
 
## commit any working changes on branch "mybranchname", then...
git checkout master
git checkout -b mybranchname_temp
git merge --squash mybranchname
git commit -am "Message describing all squashed commits"
git branch -m mybranchname mybranchname_unsquashed
git branch -m mybranchname