Bchscheme Environment Variables - MIT/GNU Scheme 7.7.90+
Description: MIT/GNU Scheme 7.7.90+

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#### 2.6.2 Environment Variables for `bchscheme`

These environment variables are referred to by `bchscheme` (not by `scheme`).

`MITSCHEME_GC_DIRECTORY`
  The directory in which GC files are written. Overridden by `--gc-directory`. The default for this variable is the standard temporary directory (see `TMPDIR` in see Runtime Environment Variables).
`MITSCHEME_GC_FILE` (default: `GCXXXXXX`)
  The name of the file to use for garbage collection. If it ends in 6 ``X`'s, the ``X`'s are replaced by a letter and process id of the scheme process, thus generating a unique name. Overridden by `--gc-file`.
`MITSCHEME_GC_START_POSITION` (default: ``0`')
  The first position in the GC file to use. Overridden by `--gc-start-position`.
`MITSCHEME_GC_END_POSITION` (default: start-position+heap-size)
  The last position in the GC file to use. Overridden by `--gc-end-position`.
`MITSCHEME_GC_WINDOW_SIZE` (default: ``16`')
  The size in blocks of windows into new space (in the GC file). Overridden by `--gc-window-size`.

The following environment variables are only used by an experimental version of Bchscheme that uses unix System V-style shared memory, and then only if the `gcdrone` program is installed:

`MITSCHEME_GC_DRONE` (default: `gcdrone`)
  The program to use as the I/O drone during garbage collection. Overridden by `--gc-drone`.
`MITSCHEME_GC_READ_OVERLAP` (default: ``0`')
  The maximum number of simultaneous read operations. Overridden by `--gc-read-overlap`.
`MITSCHEME_GC_WRITE_OVERLAP` (default: ``0`')
  The maximum number of simultaneous write operations. Overridden by `--gc-write-overlap`.