When using a text editor it is sometimes really useful to have line numbers. This is especially useful when programming as sometimes an error message will indicate which line has a potential problem, it may not always be this line but it is a starting point.
If you are using the joe text editor under a Linux system, then you can enable line numbers by editing the joerc file. The file located at /etc/joe/jioerc is for global settings, if you want to do anything specific for your user then you need to copy this file to your home directory.
You also need to be root (or have root privileges )n order to edit the global settings. See your system administrator or ask for help if you are unsure.
Instructions for this can be found in this article on techrepublic.
You can edit this file by using joe joerc from within /etc/joe/. As the instructions to copy to your home directory also rename the file to .joerc, (note period prefix) then it sets the file to hidden so you need to use joe .joerc. If you have copied to your home directory remember you need to edit as your user and not the root user.
Once the file is opened scroll down to the section show above and delete the indent, the colour will change from green to white, which then shows that feature is enabled. You can set lots of other items in this file too.
Save the file ^KD and exit ^KX where ^ is the control key. When you reopen the editor you should have line numbers.
Hope this is helpful.