How to insert newline character after comma in `),(` with sed?

Question

How to insert newline character after comma in ),( with sed?

$ more temp.txt
(foo),(bar)
(foobar),(foofoobar)

$ sed 's/),(/),\n(/g' temp.txt 
(foo),n(bar)
(foobar),n(foofoobar)

Why this doesn't work?

Answer 1

sed does not support the \n escape sequence in its substitution command, however, it does support a real newline character if you escape it (because sed commands should only use a single line, and the escape is here to tell sed that you really want a newline character):

$ sed 's/),(/),\\
(/g' temp.txt
(foo),
(bar)
(foobar),
(foofoobar)

You can also use a shell variable to store the newline character.

$ NL='
'
$ sed "s/),(/,\\$NL(/g" temp.txt
(foo),
(bar)
(foobar),
(foofoobar)

Tested on Mac OS X Lion, using bash as shell.

Answer 2

OK, I know this question is old but I just had to wade trough this to make sed accept a \n character. I found a solution that works in bash and I am noting it here for others who run into the same problem.

To restate the problem: Get sed to accept the backslash escaped newline (or other backslash escaped characters for that matter).

The workaround in bash is to use:

$'\n'

In bash a $'\n' string is replaced with a real newline.

The only other thing you need to do is double escape the \n as you have to escape the slash itself.

To put it all together:

sed $'s/),(/),\\\n(/g' temp.txt
(foo),
(bar)
(foobar),
(foofoobar)

If you want it actually changed instead of being printed out use the -i

sed -i $'s/),(/),\\\n(/g' temp.txt