Groups of users can be defined in PROOF via the group file, an example of which can be found at $ROOTSYS/etc/proof/xpd.group.sample. The group file is loaded via the groupfile directive

xpd.groupfile /etc/proof/groupfile

The group file allows to define the groups and several properties of the groups. This file is currently parsed by the re-nicing mechanism implemented in XrdProofd and by the dataset manager. These applications use different directives which are explained in the dedicated sessions. Here we describe the generic directive for defining groups and assigning members to them, and to define a group property. A group named 'default' is always created and users are assigned by default to it. New groups and their members are defined using the 'group' directive. The syntax is

group name user1,user2,user3,...

A user can be member of many groups; the first occurrence sets the default group. The directive 'property' defines properties for groups. The syntax is

property groupname propertyname nominal_value [effective_value] .

If missing, the effective value is set to the nominal value. Starting with ROOT version 5.27/04 (SVN rev 33458) it is possible to include recursively files in the group file via the directive 'include':

include /etc/proof/subgroupfile

This allows to reduce repetitions when configuring common and ad-hoc parts for different sites.