probably I missed something?
Code:
user@host$ echo '--BEGIN PRIVATE KEY--\nAAA\nBBB\nCCC\n--END PRIVATE KEY--'
--BEGIN PRIVATE KEY--\nAAA\nBBB\nCCC\n--END PRIVATE KEY--
user@host$ echo -e '--BEGIN PRIVATE KEY--\nAAA\nBBB\nCCC\n--END PRIVATE KEY--'
--BEGIN PRIVATE KEY--
AAA
BBB
CCC
--END PRIVATE KEY--
user@host$ printf -- '--BEGIN PRIVATE KEY--\nAAA\nBBB\nCCC\n--END PRIVATE KEY--'
--BEGIN PRIVATE KEY--
AAA
BBB
CCC
--END PRIVATE KEY--user@host$
user@host$
but your last post is not related to the original question at all (no bash, no replace text).
Please do not use:
Code:
cat file | sed 'script'
# but
sed 'script' file