为了使它完整，也可以这样做:

echo "a,b" | sed "s/,/\\$(echo -e '\n\r')/"

macOS Mojave上的sed于2005年发布，因此一种解决方案是安装gnu-sed，

brew install gnu-sed

然后使用gsed就可以了，

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

如果你更喜欢sed，只需sudo sh -c 'echo /usr/local/opt/gnu-sed/libexec/gnubin > /etc/paths.D /brew'，由brew info gnu-sed推荐。重新启动term，然后命令行中的sed为gsed。

sed 's/,/\
/g'

适用于Mac OS X。

虽然我写这篇文章晚了，只是更新我的发现。这个答案只适用于Mac OS X。

$ sed 's/new/
> /g' m1.json > m2.json
sed: 1: "s/new/
/g": unescaped newline inside substitute pattern

在上面的命令中，我尝试用Shift+Enter添加新行，但没有工作。所以这一次我尝试了“转义”的“未转义换行”，因为错误告诉。

$ sed 's/new/\
> /g' m1.json > m2.json 

成功了!(适用于Mac OS X 10.9.3)

只是为了澄清:OSX上sed的手册页(10.8;达尔文内核版本12.4.0)说:

[…]

Sed正则表达式

 The regular expressions used in sed, by default, are basic regular expressions (BREs, see re_format(7) for more information), but extended
 (modern) regular expressions can be used instead if the -E flag is given.  In addition, sed has the following two additions to regular
 expressions:

 1.   In a context address, any character other than a backslash (``\'') or newline character may be used to delimit the regular expression.
      Also, putting a backslash character before the delimiting character causes the character to be treated literally.  For example, in the
      context address \xabc\xdefx, the RE delimiter is an ``x'' and the second ``x'' stands for itself, so that the regular expression is
      ``abcxdef''.

 2.   The escape sequence \n matches a newline character embedded in the pattern space.  You cannot, however, use a literal newline charac-
      ter in an address or in the substitute command.

[…]

所以我想一个人必须使用tr -如上所述-或者nitty

sed "s/,/^M
/g"

注意:你必须输入<ctrl>-v，<return>才能在vi编辑器中得到'^M'

为了使它完整，也可以这样做:

echo "a,b" | sed "s/,/\\$(echo -e '\n\r')/"