CMCDragonkai

makeWrapper and wrapProgram

Nix generally assumes run-time dependencies is a subset of the build-time dependencies.

This means many Nix builder functions try to automatically scan the output for runtime dependencies and "rewrite" them for runtime usage.

However shell scripts which are often exported by packages do not get this automatic scanning treatment.

This means you have to use the makeWrapper package and use either the makeWrapper or wrapProgram utility functions.

CMCDragonkai

Regular Expression Engine Comparison Chart

Many different applications claim to support regular expressions. But what does that even mean?

Well there are lots of different regular expression engines, and they all have different feature sets and different time-space efficiencies.

The information here is just copied from: http://regular-expressions.mobi/refflavors.html

CMCDragonkai

Job Control in ZSH and Bash

All processes in ZSH/Bash under job control are in 3 states: foregrounded, backgrounded and suspended.

# run command in the foreground
command
# run commend in the background

CMCDragonkai

HTTP Streaming (or Chunked vs Store & Forward)

The standard way of understanding the HTTP protocol is via the request reply pattern. Each HTTP transaction consists of a finitely bounded HTTP request and a finitely bounded HTTP response.

However it's also possible for both parts of an HTTP 1.1 transaction to stream their possibly infinitely bounded data. The advantages is that the sender can send data that is beyond the sender's memory limit, and the receiver can act on

CMCDragonkai

Understanding Nix Inputs

Every Nix derivation produces a Nix store output that has 3 things:

• Executables
• Libraries
• Data

Executables are always exported using the PATH environment variable. This is pretty much automatic.

CMCDragonkai

Trusted SSL/TLS Certificate Stores on Linux Operating Systems and Applications

The SSL/TLS store location is not standardised across operating systems or even Linux distros. It could be anywhere in:

• /etc/ssl/certs
• /etc/pki/tls/certs/ca-bundle.crt
• /etc/ssl/certs/ca-bundle.crt
• /etc/pki/tls/certs/ca-bundle.trust.crt

CMCDragonkai

# do it once
seq 1 | parallel -n0 "curl -H 'Content-Type: application/json' http://httpbin.org/post -X POST -d '{\"url\":\"http://google.com/\"}'"

# do it twice
seq 2 | parallel -n0 "curl -H 'Content-Type: application/json' http://httpbin.org/post -X POST -d '{\"url\":\"http://google.com/\"}'"

# do it 4 times, but at 2 a time
seq 4 | parallel -n0 -j2 "curl -H 'Content-Type: application/json' http://httpbin.org/post -X POST -d '{\"url\":\"http://google.com/\"}'"

# you can also put all your commands into a file

CMCDragonkai

Notes

It should be noted that:

1. Basic blocks in SSA can be identified at 3 points:

• Start of the program
• Labels
• Branches

2. Basic blocks are used in optimisation.

CMCDragonkai

Nix String and Path Concatenation

From Bas van Dijk:

To understand these things I would recommend using nix-repl:

$ nix-repl
Welcome to Nix version 1.11.2. Type :? for help.

CMCDragonkai

{"payload":"eyJpYXQiOjE3NDAwODYzMzUsImlzcyI6InZ2Y2lrdGFiMG04ZjgxZjg2MW5jcGFkaXZrbGExMDM0OHVycGE2Z3V2a2ZidHMzbDBkbWNnIiwianRpIjoidjBwdG5qZ3ZpcGhvMDFmbTlhZWw1Z2I0N2swIiwibmJmIjoxNzQwMDg2MzM1LCJwcmV2Q2xhaW1JZCI6bnVsbCwicHJldkRpZ2VzdCI6bnVsbCwic2VxIjoxLCJzdWIiOiJbXCJnaXRodWIuY29tXCIsXCJDTUNEcmFnb25rYWlcIl0iLCJ0eXAiOiJDbGFpbUxpbmtJZGVudGl0eSJ9","signatures":[{"protected":"eyJhbGciOiJFZERTQSIsImtpZCI6InZ2Y2lrdGFiMG04ZjgxZjg2MW5jcGFkaXZrbGExMDM0OHVycGE2Z3V2a2ZidHMzbDBkbWNnIn0","signature":"INujYju797NjAD7EyBhLFVafsvUIMyQW-AmG-_dT_yOev_GJnI889NEpzUSDcOCPt9rmzbWpw0Q6Bvq3SvrjDA"}]}