gistfile1.txt

wmorgan@docker1:~$ docker run --rm ubuntu /bin/bash -c 'echo -n; ls -l /proc/1/exe'
ls: cannot read symbolic link /proc/1/exe: Permission denied
lrwxrwxrwx 1 root root 0 Dec  3 18:56 /proc/1/exe
wmorgan@docker1:~$ docker run --rm --cap-add SYS_PTRACE ubuntu /bin/bash -c 'echo -n; ls -l /proc/1/exe'
ls: cannot read symbolic link /proc/1/exe: Permission denied
lrwxrwxrwx 1 root root 0 Dec  3 18:57 /proc/1/exe
wmorgan@docker1:~$ docker run --rm --privileged ubuntu /bin/bash -c 'echo -n; ls -l /proc/1/exe'
lrwxrwxrwx 1 root root 0 Dec  3 18:57 /proc/1/exe -> /bin/bash