Hard links will do for system-wide equivalences and Unix systems which do not use symbolic links. Symbolic links can be used for access to formats for individual projects. Besides being more cumbersome, however, this approach is not available to systems which do not accept aliases. This can produce executables which load faster, but the executables also consume enormous amounts of disk space. The defaults for all environment variables are set at the time of compilation in a file named site .
All paths are colon-separated.
If you set an environment variable to a value that has a leading colon, the system default shown here is prepended. Likewise for a trailing colon. All the programs in the base TeX distribution use this same search method. Normally, TeX puts its output files in the current directory. There is no default value for that variable.