Replace comma with newline in sed on MacOS?

Question

I have a file of id\'s that are comma separated. I\'m trying to replace the commas with a new line. I\'ve tried:

sed \'s/,/\\n/g\' file

b

Answer 1

Use an ANSI-C quoted string $'string'

You need a backslash-escaped literal newline to get to sed. In bash at least, $'' strings will replace \n with a real newline, but then you have to double the backslash that sed will see to escape the newline, e.g.

echo "a,b" | sed -e $'s/,/\\\n/g'

Note this will not work on all shells, but will work on the most common ones.