Reference: Raw LDAP Queries (ldapsearch)

As explained in the tutorial MDS services are based on LDAP and information is supplied by:-

1. Individual site elements (GRIS)
2. Site wide services (GIIS and site BDII)
3. Top level databases (BDII).

ldapsearch command

  Syntax:  ldapsearch [options] [filter [attributes...]]

  Options (not a complete list):-

   -x         Simple authentication (always use this)

   -p port    port on LDAP server  e.g. -p 2170
   -h host    LDAP server e.g. -h lcg-bdii.cern.ch
   -H URI     LDAP Uniform Resource Indentifier(s).  An alternative to -h -p
              e.g. -H ldap://lcg-bdii.cern.ch:2170

   -b basedn  the initial entry for the search in the LDAP tree
              e.g. -b "mds-vo-name=local, o=grid"
              GRIS Initial entry of the DIT is always o=grid
                          the second one (next level) is 'mds-vo-name=local'
              GRIIS Initial entry of the DIT is normally o=<site-name> (never o=grid) 
                          the second one (next level) is 'mds-vo-name=local'
              BDII As for GRIS

   -LLL       Print without comments and version
 

   filter

      Applies a filter to limit a search.  Filters can be simple or compound (combine sumple with & | or !)

      simple-filter:  attribute operator value 
                      e.g.  GlueHostMainMemoryRAMSize<=1000

                        Operators: = 	Entries whose attribute is equal to the value
                                   >= 	Entries whose attribute is greater than or equal to the value
                                   <= 	Entries whose attribute is less than or equal to the value
                                   =* 	Entries that have a value set for that attribute
                                   ~= 	Entries whose attribute value approximately matches the specified value 

      compound-filter:  ( "&" or "|" or "!" (simple-filter1) [(simple-filter2) ...] )
                        e.g. '(&(objectClass=GlueCE)(GlueCEAccessControlBaseRule=VO:minos))'
                        Note: - enclose in '...' to avoid shell processing the &
                              - A special attribute objectClass is defined for each directory entry. 
                                It indicates which object classes are defined for that entry in the LDAP schema. 

   attributes

      whitespace-separated list of attribute descriptions  [Default: all]
      e.g. GlueCEUniqueID GlueCEStateEstimatedResponseTime

Examples of each type:-

element: ldapsearch -x -h lcg-bdii.cern.ch -p 2170 -b "mds-vo-name=local, o=grid"
site:    ldapsearch -x -h site-bdii.gridpp.rl.ac.uk -p 2170 -b "mds-vo-name=RAL-LCG2,o=grid" 'objectclass=GlueService' GlueServiceType
         ldapsearch -x -h site-bdii.gridpp.rl.ac.uk -p 2170 -b 'Mds-Vo-name=RAL-LCG2,o=Grid' '(GlueSALocalID=minos)' \
            GlueSARoot GlueSAStateAvailableSpace GlueSAStateUsedSpace 
global:  ldapsearch -x -h lcgbdii02.gridpp.rl.ac.uk -p 2170 -b "mds-vo-name=local, o=grid"   'GlueServiceAccessControlRule=minos'
         ldapsearch -x -h lcgbdii02.gridpp.rl.ac.uk -p 2170 -b "mds-vo-name=local, o=grid" \
            'GlueCEUniqueID=heplnx206.pp.rl.ac.uk:2119/jobmanager-lcgpbs-short' GlueCEStateStatus -LLL

For more information see: @ LCG-2 User Guide: Sections 5.1.3 - 5