Returns a search result identifier or FALSE on error.
ldap_search() performs the search for a specified filter on the directory with the scope of LDAP_SCOPE_SUBTREE. This is equivalent to searching the entire directory. base_dn specifies the base DN for the directory.
There is an optional fourth parameter, that can be added to restrict the attributes and values returned by the server to just those required. This is much more efficient than the default action (which is to return all attributes and their associated values). The use of the fourth parameter should therefore be considered good practice.
The fourth parameter is a standard PHP string array of the required attributes, e.g. array("mail", "sn", "cn") Note that the "dn" is always returned irrespective of which attributes types are requested.
Note too that some directory server hosts will be configured to return no more than a preset number of entries. If this occurs, the server will indicate that it has only returned a partial results set. This occurs also if the sixth parameter sizelimit has been used to limit the count of fetched entries.
The fifth parameter attrsonly should be set to 1 if only attribute types are wanted. If set to 0 both attributes types and attribute values are fetched which is the default behaviour.
With the sixth parameter sizelimit it is possible to limit the count of entries fetched. Setting this to 0 means no limit. NOTE: This parameter can NOT override server-side preset sizelimit. You can set it lower though.
The seventh parameter timelimit sets the number of seconds how long is spend on the search. Setting this to 0 means no limit. NOTE: This parameter can NOT override server-side preset timelimit. You can set it lower though.
The eighth parameter deref specifies how aliases should be handled during the search. It can be one of the following:
LDAP_DEREF_NEVER - (default) aliases are never dereferenced.
LDAP_DEREF_SEARCHING - aliases should be dereferenced during the search but not when locating the base object of the search.
LDAP_DEREF_FINDING - aliases should be dereferenced when locating the base object but not during the search.
LDAP_DEREF_ALWAYS - aliases should be dereferenced always.
Note: These optional parameters were added in 4.0.2: attrsonly, sizelimit, timelimit, deref.
The search filter can be simple or advanced, using boolean operators in the format described in the LDAP documentation (see the Netscape Directory SDK for full information on filters).
The example below retrieves the organizational unit, surname, given name and email address for all people in "My Company" where the surname or given name contains the substring $person. This example uses a boolean filter to tell the server to look for information in more than one attribute.
From 4.0.5 on it's also possible to do parallel searches. To do this you use an array of link identifiers, rather than a single identifier, as the first argument. If you don't want the same base DN and the same filter for all the searches, you can also use an array of base DNs and/or an array of filters. Those arrays must be of the same size as the link identifier array since the first entries of the arrays are used for one search, the second entries are used for another, and so on. When doing parallel searches an array of search result identifiers is returned, except in case of error, then the entry corresponding to the search will be FALSE. This is very much like the value normally returned, except that a result identifier is always returned when a search was made. There are some rare cases where the normal search returns FALSE while the parallel search returns an identifier.