"\
This command activates or (if C<activate> is false) deactivates
all logical volumes in all volume groups.
-If activated, then they are made known to the
-kernel, ie. they appear as C</dev/mapper> devices. If deactivated,
-then those devices disappear.
This command is the same as running C<vgchange -a y|n>");
"\
This command activates or (if C<activate> is false) deactivates
all logical volumes in the listed volume groups C<volgroups>.
-If activated, then they are made known to the
-kernel, ie. they appear as C</dev/mapper> devices. If deactivated,
-then those devices disappear.
This command is the same as running C<vgchange -a y|n volgroups...>