How do I convert multi line text into one line?

Question

I'm trying to make a txt file with a generated key into 1 line. example:

<----- key start -----> lkdjasdjskdjaskdjasdkj skdhfjlkdfjlkdsfjsdlfk kldshfjlsdhjfksdhfksdj jdhsfkjsdhfksdjfhskdfh jhdfkjsdhfkjsdhfkjsdhf <----- key stop -----> 

I want it to look like:

lkdjasdjskdjaskdjasdkjskdhfjlkdfjlkdsfjsdlfkkldshfjlsdhjfksdhfksdjjdhsfkjsdhfksdjfhskdfhjhdfkjsdhfkjsdhfkjsdhf 

Notice I also want the lines <----- key start -----> and <----- key stop -----> removed. How can I do this? Would this be done with sed?

Answer 1

tr -d '\n' < key.txt 

Found on http://linux.dsplabs.com.au/rmnl-remove-new-line-characters-tr-awk-perl-sed-c-cpp-bash-python-xargs-ghc-ghci-haskell-sam-ssam-p65/