jahio

#!/usr/bin/env $SHELL
alias lsblk="lsblk -o MODEL,VENDOR,NAME,LABEL,SIZE,MOUNTPOINT,FSTYPE"
alias gramps="nix-env -p /nix/var/nix/profiles/system --list-generations"
alias nixos-rebuild="nixos-rebuild -j 6 --cores 8"
      #
      # -j is how many "jobs" or simultaneous computational processes run in tandem
      # --cores is how many CPU cores you want to use
      # How do you get these values? `cat /proc/cpuinfo` and look at the number of
      # returned "CPUs". They're zero indexed, so if you get the last one as object
      # number seven (7), you have 8 cores.

burke

# typed: true
# frozen_string_literal: true
require('dev')
require('fileutils')

module Dev
  module Helpers
    class APFSVolume
      extend(T::Sig)

rawiriblundell

# shellcheck shell=ksh
# If SH_LIBPATH is not set or null, then we try to build it
if [ -z "${SH_LIBPATH+x}" ] || [ "${#SH_LIBPATH}" -eq "0" ]; then
  for _path in /usr/local/lib/sh "${HOME}"/.local/lib/sh; do
    [ -d "${_path}" ] && SH_LIBPATH="${SH_LIBPATH}:${_path}"
  done
fi
unset -v _path
# Remove any leading colons from the construction process and export
SH_LIBPATH="${SH_LIBPATH#:}"

llllllllll

Comments on optimizations around string concatenation.

Note: The code links are to CPython 3.8.5, the most recent release when this was written.

I was recently asked about a performance optimization in CPython around using += and + for string objects. As some people may already know, if you use += or + a string, it can sometimes be just as fast as ''.join. The question was to explain when that optimization couldn't be performed.

We will be going through the following example scenarios:

Sidneys1

#!/usr/bin/env bash
HELP="Usage: $0 [-n LINES] [-p PREFIX] [-w] [-h]

Continuously displays the last '-n' lines of 'stdin'.

Parameters:
  -n         Number of lines to display (default: 5).
  -p PREFIX  Prefix lines with 'PREFIX'.
  -w         Preserve blank lines (default: false).
  -h         Display this help

infinisil

Nixpkgs Pivots

We have a number of problems that currently require full rebuilds of nixpkgs:

• glibc needs to find third-party nss modules
• cacerts needs to contain custom CA's from enterprises
• tzdata just changed frequently
• locales

Interestingly, Nix's deep pinning of cacerts and tzdata gets in the way of Nix's promise of packages working over the long term in an archival sense:

izabera

A funky shell thingy that I've never seen before

So you're in posix sh and you want to do the equivalent of this in bash:

foo | tee >(bar) >(baz) >/dev/null

(Suppose that bar and baz don't produce output. Add redirections where needed if that's not the case.)

lizthegrey

default['sshd']['sshd_config']['AuthenticationMethods'] = 'publickey,keyboard-interactive:pam'
default['sshd']['sshd_config']['ChallengeResponseAuthentication'] = 'yes'
default['sshd']['sshd_config']['PasswordAuthentication'] = 'no'

lheckemann

Expression for a buildEnv-based declarative user environment

This is one way of managing your user profile declaratively.

Alternatives include:

• an attrset-based nix-env-based environment, installed using nix-env -ir rather than nix-env --set. LnL has an overlay which shows a way of doing this.
• home-manager, which provides NixOS-like config for your $HOME

Note that this is incompatible with regular imperative use of nix-env, e.g. nix-env -iA nixpkgs.hello. It has the advantage of allowing the installation of multiple outputs of the same package much better than nix-env's builtin profile builder does.

VladimirPal

# Boolean
op.add_column('projects', sa.Column('is_closed', sa.Boolean(), server_default=sa.schema.DefaultClause("0"), nullable=False))

# DateTime
op.add_column('projects_users', sa.Column('created_at', sa.DateTime(), server_default=sa.func.current_timestamp(), nullable=False))