How to fix corrupted ps command

ps has been replaced by other stuff, that is ps is corrupted.
how to recover

easy

RUN apt-get update && apt-get install -y procps

Procps - The /proc file system utilities

procps is the package that has a bunch of small useful utilities that give information about processes using the /proc filesystem. The package includes the programs ps, top, vmstat, w, kill, free, slabtop, and skill.