Question

I ran roscore after setcap cap_net_admin,cap_net_raw+eip /usr/bin/python3.8 operation and below is the error I got. But the pyhton code below works properly.

opt/ros/noetic/lib/rosout/rosout: error while loading shared libraries: libroscpp.so: cannot open shared object file: No such file or directory process[rosout-1]: started with pid [10399] started core service [/rosout] [rosout-1] process has died [pid 10399, exit code 127, cmd /opt/ros/noetic/lib/rosout/rosout
    __name:=rosout __log:=/home/bee/.ros/log/430043e8-0177-11ee-b48f-df7e4d4418d2/rosout-1.log]. log file: /home/bee/.ros/log/430043e8-0177-11ee-b48f-df7e4d4418d2/rosout-1*.log [rosout-1] restarting process

After running the setcap -r /usr/bin/python3 process, roscore works fine, but the python code below does not work properly, giving an authorization error.

import pysoem
def test_pysoem():
    master = pysoem.Master()
    result = master.open("enp1s0")
    master.close()

Error (without setuid privileges in python3.8):

$ python3.8  pysoem_test.py

> Traceback (most recent call last):  
> File "ethercat_test.py", line 19, in
> <module>
>  master.open('enp1s0')   File "pysoem/pysoem.pyx", line 201, in pysoem.pysoem.CdefMaster.open
> ConnectionError: could not open interface enp1s0

I am using ubuntu 20.04.6 and ros noetic. I've run it this way with the melodic before.

$printenv | grep ROS

ROS_VERSION=1
ROS_PYTHON_VERSION=3
ROS_PACKAGE_PATH=/opt/ros/noetic/share
ROSLISP_PACKAGE_DIRECTORIES=
ROS_ETC_DIR=/opt/ros/noetic/etc/ros
ROS_MASTER_URI=http://localhost:11311
ROS_ROOT=/opt/ros/noetic/share/ros
ROS_DISTRO=noetic

$ echo $LD_LIBRARY_PATH 
/home/bee/catkin_ws/devel/lib:/opt/ros/noetic/lib

Why does roscore give an error when giving setuid permissions to python3.8?

Asked by miksi on 2023-06-02 14:33:19 UTC

Answer 1

setcap cap_net_admin,cap_net_raw+eip /usr/bin/python3.8

It is an extremely bad practice to run all python programs with root privilege, even on your personal laptop. DO NOT DO THIS!

There are a number of better ways to give one ros node extra permissions. The launch-prefix="sudo -E" is discussed in #q165246; it assumes that you configure sudo to not require a password for your user account.

Asked by Mike Scheutzow on 2023-06-04 07:51:30 UTC

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I added the following lines to the sudoers file.

bee ALL=(ALL) NOPASSWD: /usr/bin/python3
bee ALL=(ALL) NOPASSWD: /opt/ros/noetic/bin/roslaunch

I tried the following commands one by one

launch-prefix="sudo -HE env PATH=${PATH} LD_LIBRARY_PATH=${LD_LIBRARY_PATH} PYTHONPATH=${PYTHONPATH}"

launch-prefix="sudo -S -HE env PATH=${PATH} LD_LIBRARY_PATH=${LD_LIBRARY_PATH} PYTHONPATH=${PYTHONPATH}"

the error I got:

sudo: a terminal is required to read the password; either use the -S option to read from standard input or configure an askpass helper

i couldn't solve this error

Asked by miksi on 2023-06-15 08:24:55 UTC

We are getting way off-topic for ros, but I will give a short answer. Assuming your username is bee, then the syntax for new file /etc/sudoers.d/bee is this single line:

bee   ALL=(ALL:ALL) NOPASSWD: ALL

As explained in the link I provided, the launch file syntax is launch-prefix="sudo -E". That's it. Do not use -H. Do not use -S. Do not override existing environment variables.

Asked by Mike Scheutzow on 2023-06-16 07:57:49 UTC

libroscpp.so: cannot open shared object file: No such file or directory

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