What is LDIF, and what does an entry look like in it?

LDIF (LDAP Data Interchange Format) is a plain-text format for LDAP entries and changes: a dn line followed by one "attribute: value" pair per line; it is used to store, export, import, back up and migrate directory data.

A shortened example of a person entry in LDIF:

dn: cn=James Bond,ou=MI6,dc=gov,dc=uk
objectClass: top
objectClass: person
objectClass: organizationalPerson
objectClass: inetOrgPerson
cn: James Bond
sn: Bond
title: Commander
telephoneNumber: 020 7930 9007
mail: jbond@mi6.gov.uk

The rules are simple: one entry per block, blocks separated by a blank line, attribute and value separated by a colon. Binary values (a photo, a certificate) are written Base64-encoded with a double colon (jpegPhoto:: /9j/4AAQ...). Besides full entries, LDIF can also describe changes (changetype: modify with add:, replace: or delete: lines), so one file can apply many updates in a batch.

Go deeper:

• RFC 2849: The LDIF technical specification — the format, including Base64 values and change records, with examples.
• LDAP Data Interchange Format (Wikipedia) — a short overview with content and change-record samples.