Insert newline (\n) using sed

The sed on BSD does not support the \n representation of a new line (turning it into a literal n):

$ echo "123." | sed -E 's/([[:digit:]]*)\./\1\n next line/'
123n next line

GNU sed does support the \n representation:

$ echo "123." | gsed -E 's/([[:digit:]]*)\./\1\nnext line/'
123
next line

Alternatives are:

Use a single character delimiter that you then use tr translate into a new line:

$ echo "123." | sed -E 's/([[:digit:]]*)\./\1|next line/' | tr '|' '\n'
123
next line

Or use an escaped literal new line in your sed script:

$ echo "123." | sed -E 's/([[:digit:]]*)\./\1\
next line/'
123
next line

Or define a new line:

POSIX:

nl='
'

BASH / zsh / others that support ANSI C quoting:

nl=$'\n'

And then use sed with appropriate quoting and escapes to insert the literal \n:

echo "123." | sed 's/\./'"\\${nl}"'next line/'
123
next line

Or use awk:

$ echo "123." | awk '/^[[:digit:]]+\./{sub(/\./,"\nnext line")} 1'
123
next line

Or use GNU sed which supports \n

The portable way to get a newline in sed is a backslash followed by a literal newline:

$ echo 'foo' | sed 's/foo/foo\
bar/'
foo
bar

I guarantee there's a far simpler solution to your whole problem by using awk rather than sed though.

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