listmanager allows you to manage text files as lists. It helps you add and delete lines with filtering for existing lines.
Use listmanager to help you create text lists. It can prevent you adding duplicate lines, it can sort and reverse-sort lines. It can also batch convert to lowercase, uppercase and lowercase mix, or lowercase. It can also batch import lists, merging two text lists together. When batch importing, you can also specify if you want to only import lines of a given character count as well.
Tested on Xubuntu 19.10, MacOS 10.11, and Windows 10 1909.
If you have any suggestions, please get in touch via email. Many thanks.