Delete empty lines using sed

Question

I am trying to delete empty lines using sed:

sed '/^$/d' 

but I have no luck with it.

For example, I have these lines:

xxxxxx   yyyyyy   zzzzzz 

and I want it to be like:

xxxxxx yyyyyy zzzzzz 

What should be the code for this?

Answer 1

You may have spaces or tabs in your "empty" line. Use POSIX classes with sed to remove all lines containing only whitespace:

sed '/^[[:space:]]*$/d' 

A shorter version that uses ERE, for example with gnu sed:

sed -r '/^\s*$/d' 

(Note that sed does NOT support PCRE.)