author Kyle Huey <>
Sat, 15 Mar 2014 12:00:15 -0700
changeset 190962 32f48d6d3389ea5db45cfc6e452ec52595c11a43
parent 163399 c5906eed61fcc7a83f8ed23cdbbc868d6c45aaaf
child 214041 7ac8d502c5948902b7ccacc6d10d013b20764a92
permissions -rw-r--r--
Bug 967364: Rename already_AddRefed::get to take. r=bsmedberg

.. _environment_variables:

Environment Variables Impacting the Build System

Various environment variables have an impact on the behavior of the
build system. This document attempts to document them.

   If defines, the build system will automatically clobber as needed.
   The default behavior is to print a message and error out when a
   clobber is needed.

   This variable is typically defined in a :ref:`mozconfig <mozconfig>`
   file via ``mk_add_options``.

   If defined, the build system will print information about why
   certain files were rebuilt.

   This feature is disabled by default because it makes the build slower.

   If defined, the terminal footer displayed when building with mach in
   a TTY is disabled.

   If defined, mach commands will not prefix output lines with the
   elapsed time since program start. This option is equivalent to
   passing ``--log-no-times`` to mach.

   Activate an *experimental* build mode where make directory traversal
   is derecursified. This mode should result in faster build times at
   the expense of busted builds from time-to-time. The end goal is for
   this build mode to be the default. At which time, this variable will
   likely go away.

   A value of ``1`` activates the mode with full optimizations.

   A value of ``no-parallel-export`` activates the mode without
   optimizations to the *export* tier, which are known to be slightly

   A value of ``no-skip`` activates the mode without optimizations to skip
   some directories during traversal.

   Values may be combined with a comma.