Sebastian Gassner sepastian

## jupyter_remote_via_ssh_tunnel.txt
# SSH into remote host "R", startup Jupyter on port XXXX.
ssh user@remotehost.com
jupyer notebook --no-browser --port=XXXX

# On the localhost "L", accessing jupyter via the browser:
# create a reverse tunnel, forwarding YYYY (L) to XXXX (R).
ssh -N -L YYYY:localhost:XXXX user@remotehost.com
          ---- --------- ----
            |       |      |
            |       |      ` port on remote where Jupyer is listening

## img2pdf.sh
#!/bin/bash

# Current directory contains a folder named 'img',
# which contains images nested in subfolders, e.g.
#
# img
#   folder1
#     img1.jpg
#     img2.jpg
#   folder2

## go_install_imports.sh
# Using go get can be confusing, here's what I learned.
#
# When go get ./... failed in a Dockerfile on Dockerhub, I listed and installed dependencies manually.
# Inspired by https://dave.cheney.net/2014/09/14/go-list-your-swiss-army-knife
#
# Recursively search for dependencies in $GOPATH/src; install dependencies using go get.
find "${GOPATH}/src" -type d \
  -exec go list -f '{{ join .Imports "\n" }}' -e {} + \
  | sort -u \
  | xargs go get -v

## eduroam_uni_passau_cert_file.sh
# First, install certificate with https://www.zim.uni-passau.de/dienstleistungen/netzwerk-und-server/netzwerkzugang/eduroam/fuer-uniangehoerige/linux/
# This will created ~/.cat_installer/user.p12 and ~/.cat_installer/ca.pem, which are the certificates required to connect.

# Create eduroam config for wpa_supplicant.
# ZIMID is your ZIM identifier, e.g. abcdef99
cat > /tmp/eduroam.conf <<EOF
network={
  ssid="eduroam"
  key_mgmt=WPA-EAP
  pairwise=CCMP

## magic_sysrq_keys.txt
https://en.wikipedia.org/wiki/Magic_SysRq_key

## gist:bfd34fa7d4716b74351b7ed03e24d686
# Prerequisites:
# - gdal2tiles.py (https://gdal.org/)
# - map.tit, a GeoTIFF file generated, for example, by QGIS

$ sudo apt install gdal-bin
$ gdal2tiles.py map.tif tiles
$ cd tiles && python -m http.server

# Go to http://localhost:8000/leaflet.html;
# place tiles/ on a web server and create a L.tileLayer using the tiles.

## mongo_index_hint.js
// Extract is a nested document, which exists in some documents only.
//
// Collection data defines a partial index on extract.created_at.
//
// Finding documents which have extract set takes long, if the collection is large.
//
// Use hint() to search the index extarct.created_at in determining, if extract exists.
db.data.getIndices()
/*
{

## pdftk_rotate_even_odd_pages_differently.sh
#!/bin/bash
set -euo pipefail
IFS=$'\n\t'
# From https://unix.stackexchange.com/a/18631/56290
# Rotate even pages by 180 degrees, don't rotate odd pages.
pdftk A=infile.pdf shuffle Aoddnorth Aevensouth output outfile.pdf

## git_self_signed_cert_file.sh
# Touch a file containing self-signed certificates to be used by git.
touch ~/.git-certs
chmod 600 ~/.git-certs

# Append the certificate to the file created aboe.
# https://stackoverflow.com/questions/7885785/using-openssl-to-get-the-certificate-from-a-server#comment26410932_7886248
echo \
  | openssl s_client -connect my.server.com:443 2>&1 \
  | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' \
  >> ~/.git-certs

## jq.sh
# Match .msg against case-insensitive regex;
# output .name and .time of matching documents.
jq 'select(.msg|test("aggregating variable";"i")) | .name,.time' input.json

# Output single line, as CSV.
jq -c 'select(.msg|test("aggregating variable";"i")) | .name,.time' input.json | tr -d '[]'

# Output value, default to 0, if field is missing.
jq '.value // 0' input.json
	# SSH into remote host "R", startup Jupyter on port XXXX.
	ssh user@remotehost.com
	jupyer notebook --no-browser --port=XXXX

	# On the localhost "L", accessing jupyter via the browser:
	# create a reverse tunnel, forwarding YYYY (L) to XXXX (R).
	ssh -N -L YYYY:localhost:XXXX user@remotehost.com
	---- --------- ----
	\| \| \|
	\| \| ` port on remote where Jupyer is listening
	#!/bin/bash

	# Current directory contains a folder named 'img',
	# which contains images nested in subfolders, e.g.
	#
	# img
	# folder1
	# img1.jpg
	# img2.jpg
	# folder2
	# Using go get can be confusing, here's what I learned.
	#
	# When go get ./... failed in a Dockerfile on Dockerhub, I listed and installed dependencies manually.
	# Inspired by https://dave.cheney.net/2014/09/14/go-list-your-swiss-army-knife
	#
	# Recursively search for dependencies in $GOPATH/src; install dependencies using go get.
	find "${GOPATH}/src" -type d \
	-exec go list -f '{{ join .Imports "\n" }}' -e {} + \
	\| sort -u \
	\| xargs go get -v
	# First, install certificate with https://www.zim.uni-passau.de/dienstleistungen/netzwerk-und-server/netzwerkzugang/eduroam/fuer-uniangehoerige/linux/
	# This will created ~/.cat_installer/user.p12 and ~/.cat_installer/ca.pem, which are the certificates required to connect.

	# Create eduroam config for wpa_supplicant.
	# ZIMID is your ZIM identifier, e.g. abcdef99
	cat > /tmp/eduroam.conf <<EOF
	network={
	ssid="eduroam"
	key_mgmt=WPA-EAP
	pairwise=CCMP
	# Prerequisites:
	# - gdal2tiles.py (https://gdal.org/)
	# - map.tit, a GeoTIFF file generated, for example, by QGIS

	$ sudo apt install gdal-bin
	$ gdal2tiles.py map.tif tiles
	$ cd tiles && python -m http.server

	# Go to http://localhost:8000/leaflet.html;
	# place tiles/ on a web server and create a L.tileLayer using the tiles.
	// Extract is a nested document, which exists in some documents only.
	//
	// Collection data defines a partial index on extract.created_at.
	//
	// Finding documents which have extract set takes long, if the collection is large.
	//
	// Use hint() to search the index extarct.created_at in determining, if extract exists.
	db.data.getIndices()
	/*
	{
	#!/bin/bash
	set -euo pipefail
	IFS=$'\n\t'
	# From https://unix.stackexchange.com/a/18631/56290
	# Rotate even pages by 180 degrees, don't rotate odd pages.
	pdftk A=infile.pdf shuffle Aoddnorth Aevensouth output outfile.pdf
	# Touch a file containing self-signed certificates to be used by git.
	touch ~/.git-certs
	chmod 600 ~/.git-certs

	# Append the certificate to the file created aboe.
	# https://stackoverflow.com/questions/7885785/using-openssl-to-get-the-certificate-from-a-server#comment26410932_7886248
	echo \
	\| openssl s_client -connect my.server.com:443 2>&1 \
	\| sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' \
	>> ~/.git-certs
	# Match .msg against case-insensitive regex;
	# output .name and .time of matching documents.
	jq 'select(.msg\|test("aggregating variable";"i")) \| .name,.time' input.json

	# Output single line, as CSV.
	jq -c 'select(.msg\|test("aggregating variable";"i")) \| .name,.time' input.json \| tr -d '[]'

	# Output value, default to 0, if field is missing.
	jq '.value // 0' input.json