Collection of Bash code snippets, mostly one liners, to ease file handling among other things

Collection of notes

rename files to reverse order

#### rotate all images using imagemagick  

```mogrify -rotate 180 *.jpg```    
```mogrify``` overwrites existing images which is what makes it different from ```convert```  
#### cut poly-shape out of image, crop image to its boundaries, fill surrounding holes in certain color or transparent (for all jpgs in folder)  

```for f in ./*.jpg; do convert "$f" \( -clone 0 -fill black -colorize 100 -fill white -draw "polygon 3276,2421 4945,2407 4956,4708 3287,4722" \) -alpha off -compose copy_opacity -composite -trim +repage 41050648/"$f"_left.jpg; done```  
#### do something inside each folder of this folder  

for d in */; do
cd $d;
for dir in */; do

for frontpage in "$dir"*.jpg; do  
  echo convert "$frontpage" -resize 500x500 "$frontpage"_500px.jpg  
  break 1  
done  

done
cd ..;
done ```