The following will concatenate continuation lines in an LDAP dump in ldif format to a “relaxed” ldif format with arbitrary long lines:
sed -n '1h;1!H;${g;s/\n //g;p;}' /tmp/ldap_schema.ldif > /tmp/ldap_schema_longline.ldif
Meaning of the tokens:
1h | copy first line into hold space |
1!H | append every line but the first one to hold space |
${ | execute on last line |
g | copy hold space to pattern space |