#### 2.6.2 Environment Variables for the Runtime System ¶

These environment variables are referred to by the runtime system.

`HOME` ¶

  Directory in which to look for init files, for example `/home/joe`. Under unix `HOME` is set by the login shell.

`TMPDIR` ¶
`TEMP`
`TMP`

  Directory for various temporary files. The variables are tried in the given order. If none of them is suitable, built-in defaults are used: `/var/tmp`, `/usr/tmp`, `/tmp`.

`MITSCHEME_INF_DIRECTORY` ¶

  Directory containing the debugging information files for the Scheme system. Should contain subdirectories corresponding to the subdirectories in the source tree. By default, the information is searched for on the library path.

`MITSCHEME_LOAD_OPTIONS` ¶

  Specifies the location of the options database file used by the `load-option` procedure. The default is `optiondb.scm` on the library path.