Rotate all pictures based on EXIF orientation info:

jhead -autorot *

Add 1h30m to all jpegs EXIFs time info:

jhead -ta+1:30 *

Rename all pictures according to EXIF time info:

jhead -n%Y%m%d-%H%M%S *

Re-size all the jpg files in the current directory - keep aspect ratio and set maximal width/height to 1024 pixel:

mogrify -resize 1024x1024 *.jpg

Scale all jpgs in the current directory by 50%:

mogrify -resize 50% *.jpg