tpvasconcelos / howtos

Miscellaneous how-tos, and code snippets

Miscellaneous how-tos, and code snippets

Shell

Ask for sudo password only once

Add this to the top of your shell script.

################################################################################
# Ask for root password upfront and keep updating the existing `sudo`
# timestamp on a background process until the script finishes. Note that
# you'll still need to use `sudo` where needed throughout the scripts.
################################################################################
echo "Some of the commands in this script require root access. Enter your password to unable root access when necessary..."
sudo -v
while true; do
  sudo -n true
  sleep 30
  kill -0 "$$" || exit
done 2>/dev/null &

ffmpeg - Video from images

ffmpeg -framerate 24.994862 -i img%06d.png -c:v libx264 -vf fps=24.994862 -pix_fmt yuv420p myMovie.mp4

[FIXME] Remove local CloudDocs copies

# $ source ~/.zshrc

function _safer_evict() {
  input_path=$(realpath "$@")/
  # shellcheck disable=SC2034
  path_to_icloud=$(realpath ~/Library/Mobile\ Documents/com~apple~CloudDocs)/
  if [[ "${input_path##path_to_icloud}" != "${input_path}" ]]; then
    echo yes;
    echo "$input_path";
  fi
}

function _evictall() {
  _SAFER_EVICT=$(functions _safer_evict)
  #find "$1" -type f -not -name .DS_Store -a -not -name .\*.icloud -exec "$SHELL" -c '_safer_evict "$@"' -- {} \;
  #find "$1" -type f -not -name .DS_Store -a -not -name .\*.icloud -exec zsh -c '_safer_evict "$@"' zsh {} \;
  #  find "$1" -type f -not -name .DS_Store -a -not -name .\*.icloud -print0 | xargs -0 ls
  #find "$1" -type f -not -name .DS_Store -a -not -name .\*.icloud -print0 | xargs -0 bash -c '_safer_evict "$@"' _
  #find "$1" -type f -not -name .DS_Store -a -not -name .\*.icloud -print0 | xargs -0 -I{} "$SHELL" -c "eval $_SAFER_EVICT; _safer_evict {}"
  find "$1" -type f -not -name .DS_Store -a -not -name .\*.icloud -print0 | xargs -0 -I{} "$SHELL" -c "eval ${_SAFER_EVICT}; ls {}"
}

_evictall "$1"

SQL

Compare two queries

Use the following template to get the difference between two queries:

with q1 as (
    <INSERT_Q1_HERE>
)
, q2 as (
    <INSERT_Q2_HERE>
)
, missing_from_q2 as (
    select *
    from (
        select * from q1 
        except 
        select * from q2
    )
    cross join (select 'missing from q2' as diff_description)
)
, missing_from_q1 as (
    select *
    from (
        select * from q2 
        except
        select * from q1
    )
    cross join (select 'missing from q1' as diff_description)
)
select * from missing_from_q2
union all
select * from missing_from_q1

References:

• https://stackoverflow.com/questions/11017678/sql-server-compare-results-of-two-queries-that-should-be-identical/63380681#63380681

[Amazon Redshift] Disable results caching for current session

set enable_result_cache_for_session to off;

References:

• https://docs.aws.amazon.com/redshift/latest/dg/r_enable_result_cache_for_session.html

Kubernetes

Sync current git working tree to a k8s pod

This utility helps you sync your current git working tree with a remote k8s pod. This assumes that the project is cloned under /home/jovyan on the remote pod. The repository name will be inferred from the current repository using git rev-parse --show-toplevel. For this to work, you also need to have rsync installed in the remote k8s pod (run: sudo apt install rsync grsync). Note that the .git/ directory will not be synced. In addition to this, nothing in .gitignore will be synced.

Simply add a copy of snippets/k8s/krsync.zsh and snippets/k8s/krsync-subshell.sh to the top level directory of your git repository and run ./krsync.zsh my-pod.

• https://serverfault.com/questions/741670/rsync-files-to-a-kubernetes-pod

Misc

GitHub Markdown style on JetBrains IDEs

Inspired and adapted from https://github.com/sindresorhus/github-markdown-css

1. Open the Preferences -> Language & Frameworks -> Markdown
2. Copy the contents of snippets/misc/github-markdown.css into the open text box under Custom CSS -> Add CSS rules

References:

• https://www.jetbrains.com/help/idea/markdown.html#css

Custom playback rate for Udemy videos

document.querySelector("video").playbackRate = 1.2

// The above line above should be enough as there should only be a single <video> element
// document.querySelector(".video-player--video-player--1sfof").querySelector("video").playbackRate = 1.2

References:

• https://github.com/gitnix/chrome-extension-udemy-playback-rate