I solved this already, but basically I was getting java.io.EOFException while installing Forge.
From the (scarce) other forum postings on this, I needed to either clear the temp directory or delete some folder in `.minecraft/libraries`. The other forum posts were for Windows, so I have no idea what temp folder they mean exactly, I doubt it is `/tmp`. If someone can clarify where the download cache is for the Forge installer on Linux, that would be really nice.
Solution:
In terminal, `cd` to your `.minecraft` folder, likely this command is what you want: `cd ~/.minecraft`.
Run `find -name '*1.20.1*'`, or replace 1.20.1 with the version you're installing. This shows where the damaged files might be which cause this error.
Very carefully, determine which folders are safe to delete with `rm -rf`. The commands I ran were:
rm -rf ./versions/1.20.1*
rm -rf ./libraries/de/oceanlabs/mcp/mcp_config/1.20.1*
rm -rf ./libraries/net/minecraftforge/fmlcore/1.20.1-47.3.22
rm -rf ./libraries/net/minecraftforge/forge/1.20.1-47.3.22
rm -rf ./libraries/net/minecraftforge/mclanguage/1.20.1-47.3.22
After this I reran the install and it worked fine.
