Sed/Awk - remove blankspaces / join lines in ldif dump

Question

I got some entries in my ldif file that makes my dump bad for next import.

sambaPasswordHistory: 712BC301C488FD2651BEF5AA11899950547B9ED3C059FF83CE39049B
 BAEECB31692629A94A3C1F4737E3EA854C001704793DB9A67EB977563CE601DF98E7E23C2851F
 082D3D695C8655378629DCCDAF125ACA63141B361190ABC750AF403FDEF000000000000000000
 00000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000000000000000000000000000000000000000000000000000000000000000000000000
 000000000000000000000000000000000000000000000000000000000
homeDirectory: /home_nfs/

How can I make using sed/awk/etc to change it to

sambaPasswordHistory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
homeDirectory: /home_nfs/

Aka keep everything in one line

Answer 1

$ cat file
sambaPasswordHistory: abc
 def
 12345
 67
homeDirectory: /home_nfs/
$
$ awk 'NR>1 && !sub(/^ /,""){print s; s=""} {s = s $0} END{print s}' file
sambaPasswordHistory: abcdef1234567
homeDirectory: /home_nfs/

Answer 2

One way using GNU sed:

sed -n 'H; ${ x; s/\n//; s/\n //g; p}' file.txt

Result:

sambaPasswordHistory: 712BC301C488FD2651BEF5AA11899950547B9ED3C059FF83CE39049BBAEECB31692629A94A3C1F4737E3EA854C001704793DB9A67EB977563CE601DF98E7E23C2851F082D3D695C8655378629DCCDAF125ACA63141B361190ABC750AF403FDEF000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
homeDirectory: /home_nfs/