Can sed remove ‘double’ newline characters

sed

I have a document with a lot of empty lines.

How can I remove them when there are 2 or more together.

I tried sed "s/\n\n//" file but it didn't work. No error.

Best Answer

Just to remove empty lines:

sed  '/^$/d'

sed is line oriented, so thinking in terms of "2 or more of a particular byte" works except when that byte is a newline. Then you have to think of something that works for the whole line.

Related Solutions

Using sed to get rid of characters < > ,

With sed:

sed 's|[<>,]||g'

With tr:

tr -d '<>,'

Can Sed Replace New Line Characters?

With GNU sed and provided POSIXLY_CORRECT is not in the environment (for single-line input):

sed -i ':a;N;$!ba;s/\n/,/g' test.txt

From https://stackoverflow.com/questions/1251999/sed-how-can-i-replace-a-newline-n :

create a label via :a
append the current and next line to the pattern space via N
if we are before the last line, branch to the created label $!ba ($! means not to do it on the last line (as there should be one final newline)).
finally the substitution replaces every newline with a comma on the pattern space (which is the whole file).

Best Answer

Related Solutions

Using sed to get rid of characters < > ,

Can Sed Replace New Line Characters?

Related Question