Linux Environment Variables
Environment variables may look like a bunch of scattered names and values, but they actually determine where commands look for executables, how programs run, and which default settings tools read. Once you understand variables like PATH, HOME, and LD_LIBRARY_PATH, many environment configuration issues go from "black magic" to something you can actually diagnose.
This course material can be reviewed alongside Conda, compilation-based installation, and CUDA environment configuration. A lot of software that installs fine but won't run ultimately comes down to environment variables.