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/* futex_demo.c

   Usage: futex_demo [nloops]
                    (Default: 5)

   Demonstrate the use of futexes in a program where parent and child
   use a pair of futexes located inside a shared anonymous mapping to
   synchronize access to a shared resource: the terminal. The two
   processes each write 'num-loops' messages to the terminal and employ
   a synchronization protocol that ensures that they alternate in

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/* Demonstrate how to overwrite the original value of
   an environment variable in the original environment vector
   that is easily observable from other processes
   (with sufficient permissions, i.e. same user or root).
 */

/** {{{ MIT No Attribution

Copyright 2019 Georg Sauthoff <[email protected]>

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#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>

int main()
{
    int pid = vfork();
    if (pid == 0) {
        _exit(0);
    }

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class Last_Lines:
  def __init__(self, n, binary=True):
    self.n = n
    self.binary = binary
    self.lines = []
    # asyncssh calls fstat() on fileno() and checks if it is a regular file
    # thus we open any regular file to fake it ...
    self.dev_null = open('/etc/resolv.conf')
  def write(self, s):
    lines = s.splitlines(True)

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# in reply to: https://groups.google.com/d/msg/django-developers/6mm42rrQXww/Yee5KJjVBQAJ
# (pull request: write feeds with ordered attributes)
# cf. https://github.com/django/django/pull/8044
#
# Results:
# - generating one feed: ~ 0.01 s (current Laptop, i7, SSD)
# - sorting + OrderedDict() in SimpleXMLGenerator::startElement(): + ~ 27 %
# - sorting + OrderedDict() iff there are attributes: + ~ 18 %
# - replacing {} with [] for attributes in feedgenerator: + ~ 7 %

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/* For illustrating how orphaned children aren't necessarily adopted
   by PID 1.

   See also: http://stackoverflow.com/questions/284325/how-to-make-child-process-die-after-parent-exits/36945270#36945270

   2016, Georg Sauthoff <[email protected]>
*/


#include <unistd.h>

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// re: http://stackoverflow.com/questions/28489153/how-to-portably-compute-a-sha1-hash-in-c/39833022#39833022

#include <boost/uuid/sha1.hpp>
#include <boost/detail/endian.hpp>
#include <boost/algorithm/hex.hpp>
#include <boost/range/iterator_range_core.hpp>
#include <boost/endian/conversion.hpp>
#include <iostream>
#include <stdio.h>
using namespace std;

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% curl -L -o signature.png \
%  'https://upload.wikimedia.org/wikipedia/commons/thumb/6/62/Beethoven_Signature.svg/150px-Beethoven_Signature.svg.png'
% compile twice: pdflatex sig_overlay.tex
\documentclass{article}
\usepackage{blindtext}
\usepackage{graphicx}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[remember picture,overlay]
  \node [xshift=150mm,yshift=-80mm]

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// in reply to http://verse.systems/blog/post/2016-07-18-Software-Engineering-Teaching/

unsigned fibonacci(unsigned n) {
    unsigned a = 0, b = 1;
    unsigned sum = 0;
    for ( ; n > 0; --n) {
        unsigned t = b;
        b += a;
        a = t;
        sum += a;

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/*

Illustrate how the & operator can be omitted when getting a function pointer.

In reply to: https://www.youtube.com/watch?v=z-kUhwANrIw

2016, Georg Sauthoff

 */