coDing

home using node http-server
```
cd ~
http-server -p8081
```
notes
```
cd ~
jekyll serve --watch --port 3125
```
blog
```
cd
jekyll serve --watch --port 4000
```
ddns
node root
apache root
notes
blog

loop thru directories

   for d in ./*; do   if [ -d "$d" ]; then     echo "$d";   fi; done

apply to script all files in directory

  curdir=$(pwd); for folder in /path/to/Files/*; do[ -d "$folder" ] && cd "$folder" && ./conv.sh; done; cd $curdir

  for f in *; do [ -d "$f" ] && cd "$f" && ./conv.sh; done; cd ..

concat files

  cat * > merged-file
  ```bash
  find /path/to/directory/ -name *.csv -exec cat {} + > merged.file

replace text in batch

  sed -i.backupsuffix 's/SEARCH_REGEX/REPLACEMENT/g' INPUTFILE

find large files

  sudo find . -xdev -type f -size +100M

delete files

  for d in ./*; do   if [ -d "$d" ]; then  cd $d; rm *.mp3; cd .. ;   fi; done

rename files

  rename -v  's/search regex/replacingstring/' *

rename files sequentially

ls | cat -n | while read n f; do mv "$f" `printf "2019-12-02-23-19-%02d.jpg" $n`; done

rename and keep extension no recursion thru directories

ls -1prt | grep -v "/$" | cat -n | while read n f; do mv -n "${f}" "$(printf "%04d" $n).${f#*.}";

RegExNegative Lookahead
```
  (?!NO)
```
RegEx Greedy WildCard
```
  ([^~]*?)
```

make thumbnails

  for f in *.pdf; do echo epub-thumbnailer \'$f\' \'${f%.epub}.png\' 800"; done

  for f in *.pdf; do convert -thumbnail x800 -background white -alpha remove "$f"[0] "${f%.pdf}.png"; done

  mogrify  -format webp -path thumbs -thumbnail 200x200 *.pdf[0] *.png  *.gif[0] *.djvu[0] *.jpg

trim a video of leng hh:mm:ss of inp video beginning @ time HH:MM:SS

ffmpeg -i inp.mp4 -ss HH:MM:SS -t hh:mm:ss -async 1 cut.mp4

video to frames

ffmpeg -i inp.mp4 -r  1/1 $filename%03d.bmp

frames to gif

gifsicle --delay  10 --loopcount  0 *.gif  &gt; out.gif

webp to gif

  for f in *.webp; do mkdir $f.frames;anim_dump -folder $f.frames  $f;convert $f.frames/*.png -delay 10 -loop 0 $f.gif; done;

batch img

  sudo apt-get install jpegoptim

  jpegoptim *.jpg -m30

  mogrify -path ./results -resize 50x50% -quality 80 -format jpg *.png

  mogrify -format jpg *.png

  mogrify -path ./ -resize 50% -quality 80  *.jpg

  convert *.jpg -auto-orient pictures.pdf

batch music

  sudo apt-get install lame

  lame -b bitrate input.mp3 output.mp3

Images To Booklet

  img2pdf $(find . -iname '*.jpg' | sort -V) -o ./document.pdf
  ```bash
  ls -1 ./*jpg | xargs -L1 -I {} img2pdf {} -o {}.pdf; pdftk *.pdf cat output combined.pdf

  img2pdf *.jpg -o ./document.pdf

compress pdf

  gs -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -sOutputFile=output.pdf input.pdf

  gs -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -sOutputFile=output.pdf input.pdf

  ps2pdf -dPDFSETTINGS=/ebook input.pdf output.pdf

  convert -density 200x200 -quality 40 -compress jpeg input.pdf output.pdf

compress vids

  ffmpeg -i source.mp4 -c:v libx264 -b:v 0.5M -c:a aac -b:a 96k target.mp4

  ffmpeg -i source.mp4 -c:v libx264 -b:v 1.5M -c:a aac -b:a 128k target.mp4

invert color
```
html {-filter: invert(100%)}
```

for MD checklist

<!-- Required extensions: pymdownx.tasklist -->

for GFM

<!-- Required extensions: pymdownx.betterem, pymdownx.tilde, pymdownx.emoji, pymdownx.tasklist, pymdownx.superfences -->

wget options
- E: Append .html to the file name if it is an HTML file but doesn’t end in .html or similar
- H: Download files from other hosts, too
- k: After downloading convert any link in it so they point to the downloaded files
- p: Download anything the page needs for proper offline viewing
- r: recursively download all files in folder
download website
```
  wget -r -k - E -p  link
```
download webpage
```
  wget -E -H -k -p link
```

get gdrive files from url

  if [[ $URL =~ d/(.*)/view ]]; then  FILEID=${BASH_REMATCH[1]}; else if [[ $URL =~ open.id=(.*?)\" ]]; then  FILEID=${BASH_REMATCH[1]}; fi ; fi

  wget --no-check-certificate "https://docs.google.com/uc?export=download&id=$FILEID" -O   "$FILENAME"

  wget --load-cookies /tmp/cookies.txt "https://docs.google.com/uc?export=download&confirm=$(wget --quiet --save-cookies /tmp/cookies.txt --keep-session-cookies --no-check-certificate "https://docs.google.com/uc?export=download&id=$FILEID" -O- | sed -rn 's/.*confirm=([0-9A-Za-z_]+).*/\1\n/p')&id=$FILEID" -O  "$FILENAME"  && rm -rf /tmp/cookies.txt

download link
```
wget link -O outputname
```
download list of links
```
wget -i input.txt
```

mathJax

tag

<script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>

displayed mathematics delimeter
```
$$...$$
```
```
\[...\]
```
in-line mathematics delimiter
```
$...$
```

backup installation list
```
dpkg --get-selections > mylists.list
```