short-description: Configuring a pre-generated build directory ...
Often you want to change the settings of your build after it has been generated. For example you might want to change from a debug build into a release build, set custom compiler flags, change the build options provided in your meson_options.txt file and so on.
The main tool for this is the meson configure command. You may also use the mesongui graphical application if you want. However this document describes the use of the command line client.
You invoke meson configure by giving it the location of your build dir. If omitted, the current working directory is used instead. Here's a sample output for a simple project.
Core properties Source dir /home/jpakkane/clangdemo/2_address Build dir /home/jpakkane/clangdemo/2_address/buildmeson Core options type Build type debug strip Strip on install False coverage Coverage report False pch Precompiled headers True unity Unity build False Compiler flags cflags [] Linker flags clinkflags [] Directories installprefix Install prefix /usr/local libdir Library directory lib bindir Binary directory bin includedir Header directory include datadir Data directory share mandir Man page directory share/man localedir Locale file directory share/locale This project does not have any options
These are all the options available for the current project arranged into related groups. The first column in every field is the name of the option. To set an option you use the -D option. For example, changing the installation prefix from /usr/local to /tmp/testroot you would issue the following command.
meson configure -Dprefix=/tmp/testroot
Then you would run your build command (usually ninja), which would cause Meson to detect that the build setup has changed and do all the work required to bring your build tree up to date.