Gerbil Scheme

Environment Variables

Gerbil uses a few environment variables, which affect the behaviour of the runtime and toolchain:

  • GERBIL_HOME
  • GERBIL_PATH
  • GERBIL_LOADPATH

GERBIL_HOME

This is the root of your Gerbil installation.

The runtime expects the gerbil system modules to be located in $GERBIL_HOME/lib, which is set as the first component of the runtime load path. The compiler also expects to find system static compilation artifacts there.

This variable must be set for dynamic executables to be able to load the runtime. gxi and gxc can deduce it automatically from their installation path if it's not set.

GERBIL_PATH

This is the root of your Gerbil workspace, which is the read-write component of the system. If it's not set, then it defaults to ~/.gerbil.

The runtime adds $GERBIL_PATH/lib as the second component of the runtime load path.

The toolchain uses $GERBIL_PATH as default artifact output directory:

  • gxc outputs compiled modules to $GERBIL_PATH/lib, unless otherwise instructed.
  • :std/make outputs compiled modules to $GERBIL_PATH/lib and binaries to $GERBIL_PATH/bin, unless otherwise instructed.

GERBIL_LOADPATH

This is a colon separated list of directories to be appended to the runtime load path. You can use this for loading site specific libraries. By default it's unset, which is equivalent to an empty value.

GERBIL_GSC

This is the program name or path to the gsc compiler executable; defaults to gsc (or to full path to gsc, on a Nix build).

This variable is used by Gerbil v0.14-DEV-73-g7a2a91c1 and later; earlier versions hardcode gsc as the compiler program name.

GERBIL_GXC

This is the program name or path to the gxc compiler executable; defaults to gxc (or to full path to gxc, on a Nix build). Currently it is only used by std/make and std/build-script, and only when building software in parallel (which is now the default, but can be disabled with the GERBIL_BUILD_CORES variable below).

This variable is used by Gerbil v0.16-DEV-560 and later; earlier versions did not have a parallel build.

GERBIL_BUILD_CORES

This is the number of cores that std/make and std/build-script will use when building Gerbil programs, by spawning accordingly many compiler processes in parallel, (mostly instances of gxc, gsc and gcc). If a parallel: argument is provided to make or defbuild-script, it will take precedence over this variable. If no such argument is provided and the variable is undefined or invalid, the number of cores present is auto-detected from the Operating System and used.

You can wholly disable parallelism by exporting GERBIL_BUILD_CORES=0, at which point the Gerbil part of compilation will be done in the current process. By contrast, GERBIL_BUILD_CORES=1 enforces use of subprocesses for Gerbil compilation, even though only one process will be run at once.

This variable is used by Gerbil v0.16-DEV-560 and later; earlier versions did not have a parallel build.

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