Environment Variables Impacting the Build SystemΒΆ

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 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.