This is not necessarily for any question, but for rare stuff not covered anywhere else. Most of it relates to modding, some of it to rare problems.
This is caused by Lua/GMod's unintelligent handling of line endings. The rearm script files need to have Windows-style line ending markers for Windows servers, but on Linux they need to be Linux-style. Most decent text editors have an option for "EOL conversion" or similar.
If you have shell access on the linux box, you could navigate to where the scripts are and run:
That will convert all the scripts in one go. Converted scripts with proper line endings will no longer error.
Note that this works on any entity, not just ammo. So if you want to randomly spread a certain entity across the map, this might be a workable method.