>>628
cat |sed -ne "/^===/! {H;}; $ b ll; /^=/ {:ll; s/=//g; x; s/\n/ /g; p;}" << EOL
abc
def
==== 1
ghi
jkl
==== 2
mno
pqr
EOL
abc def
1 ghi jkl
2 mno pqr