-h --help

prints the short usage

-v --version

prints the version

-i --info

prints the full info page

-P --prefix

prints the installation prefix

-E --exec-prefix

prints the installation exec-prefix

-B --bindir

prints the installation bindir

-D --datadir

prints the installation datadir

-L --libexecdir

prints the installation libexecdir

-S --sysconfdir

prints the installation sysconfdir

-M --mandir

prints the installation mandir

-m --fvwm-moduledir

prints FVWM_MODULEDIR, where the modules are installed

-d --fvwm-datadir

prints FVWM_DATADIR, where the system wide configs are installed

-I --default-imagepath

prints the built-in ImagePath

-U --default-userdir

prints the default FVWM_USERDIR, note: $HOME is not expanded

-e --fvwm-exe

prints the fvwm executable name (in bindir)

-s --supports

lists all supported features, one per line

--supports-<feature>

prints nothing, returns: 0 if the <feature> is supported, 100 if not, 200 if unknown. All or supported feature names may be found using --info or --supports.

FvwmScript-Setup95 checks for the gnome-hints support:

if fvwm-config --supports-gnome-hints;
  then echo 1; else echo 0; fi

fvwm-themes package checks for the correct fvwm version installed using:

fvwm-config --version

and tries to use the same installation directories:

fvwm-config --bindir --mandir --fvwm-datadir

A way to find the full path to the fvwm executable:

echo `fvwm-config --bindir`/`fvwm-config --fvwm-exe`

For a more human readable output, try:

fvwm-config --info