Insert linefeed in sed (Mac OS X)

Question

How do I insert a newline in the replacement part of sed?

This code isn\'t working:

sed \"s/\\(1234\\)/\\n\\1/g\" input.txt > output.txt
         


        

Answer 1

The newline in the middle of the command can feel a bit clumsy:

$ echo abc | sed 's/b/\
/'
a
c

Here are two solutions to this problem which I think should be quite portable (should work for any POSIX-compliant sh, printf, and sed):

Solution 1:

Remember to escape any \ and % characters for printf here:

$ echo abc | sed "$(printf 's/b/\\\n/')"
a
c

To avoid the need for escaping \ and % characters for printf:

$ echo abc | sed "$(printf '%s\n%s' 's/b/\' '/')"
a
c

Solution 2:

Make a variable containing a newline like this:

newline="$(printf '\nx')"; newline="${newline%x}"

Or like this:

newline='
'

Then use it like this:

$ echo abc | sed "s/b/\\${newline}/"
a
c