I have Jupyter notebook installed under pyenv alias jupyter. if I run it from console (no pyenv activate jupyter, notebooks uses same port): 

```
$ export PATH=/home/mortenb/.pyenv/versions/jupyter/bin:$PATH
$ /home/mortenb/.pyenv/versions/jupyter/bin/jupyter-notebook \
  --config=/etc/jupyter/jupyter_notebook_config.py

!python --version
Python 3.6.5

!jupyter --paths
config:
    /home/mortenb/.jupyter
    /home/mortenb/.pyenv/versions/3.6.5/envs/jupyter/etc/jupyter
    /usr/local/etc/jupyter
    /etc/jupyter
data:
    /home/mortenb/.local/share/jupyter
    /home/mortenb/.pyenv/versions/3.6.5/envs/jupyter/share/jupyter
    /usr/local/share/jupyter
    /usr/share/jupyter
runtime:
    /run/user/1000/jupyter

```

Correct kernel all is fine.

But if I automate this with a systemd script, same user, same executable:

```
# cat /lib/systemd/system/jupyter_notebook.service 
[Unit]
Description=jupyter notebook as a service

[Service]
PATH=/home/mortenb/.pyenv/versions/jupyter/bin:$PATH
Type=simple
User=mortenb
Group=mortenb
PIDFile=/var/run/jupyter_notebook.pid
ExecStart=/home/mortenb/.pyenv/versions/jupyter/bin/jupyter-notebook --config=/etc/jupyter/jupyter_notebook_config.py 

[Install]
WantedBy=multi-user.target

```

I get python 2.7.12 (system python with Ubuntu 16.04)

```
!python --version
Python 2.7.12

!jupyter --paths
config:
    /home/mortenb/.jupyter
    /usr/etc/jupyter
    /usr/local/etc/jupyter
    /etc/jupyter
data:
    /home/mortenb/.local/share/jupyter
    /usr/local/share/jupyter
    /usr/share/jupyter
runtime:
    /home/mortenb/.local/share/jupyter/runtime

```

The jupyter-notebook has the following shebang in both examples:

```
#!/home/mortenb/.pyenv/versions/3.6.5/envs/jupyter/bin/python

```

Any idea why systemd startup differs.
Thanks