I installed odoo 11 by following this link
https://www.getopenerp.com/install-odoo-11-on-ubuntu-16-04/
- I added a folder name addons in my home folder 
- copied some third party apps into the folder 
- Changed ownership of folder for odoo user by typing following command (sudo chown odoo: /addons) 
- edited by odoo.conf file in etc folder. added following addons path 
 addons_path = /opt/odoo/addons,/opt/odoo/odoo/addons,/home/rck/addons,/addons
- Now when I run odoo 
- Activated developer mode with assets 
- In apps menu clicked on update module list 
- Apps fail to show?:( 
It works fine when I add these apps in main /opt/odoo/odoo/addons but it totally ignores apps if added in custom path. Please help me solve the issue. 
 
                        
Have you defined config file when running? have a look at this link https://www.odoo.com/documentation/8.0/reference/cmdline.html
I tried that too first. It doesn't show up. My addons folder is outside (ie /addons)
so I tried with following command ./odoo-bin --addons-path=addons
custom app doesn't show up.
I got it working with following command
./odoo-bin --addons-path="/opt/odoo/odoo/addons,/addons"
main thing is, we need to pass original addons path with it. Custom addons path must have atleat one working module in it.
Following link helped me solve this.
https://stackoverflow.com/questions/38670514/how-to-add-a-custom-folder-to-odoo-py-addons-addons