ppmshift
Shift the lines in a PPM image by a randomized amount. More information: https://netpbm.sourceforge.net/doc/ppmshift.html.
- Shift the lines in the input image by a randomized amount not exceeding s to the left or to the right:
ppmshift {{s}} {{path/to/input_file.ppm}} > {{path/to/output_file.ppm}}