Environment variables are also more portable and cheaper/simpler than a DBMS, a LDAP service, an application server's proprietary configuration repository, etc.

Environment variables are also more portable and cheaper/simpler than a DBMS, a LDAP service, an application server's proprietary configuration repository, etc. without being weaker at specifying simple configuration values. In practical terms, specifying environment variables in cleanly isolated and composable layers (defaults by user, a specific terminal session, a script that call another script or the useful program) is a major advantage over more enterprisey and monolithic mechanisms.