Replace comma with newline in sed on MacOS?

Use tr instead:

tr , '\n' < file

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.

sed 's/,/\
/g'

works on Mac OS X.

If your sed usage tends to be entirely substitution expressions (as mine tends to be), you can also use perl -pe instead

$ echo 'foo,bar,baz' | perl -pe 's/,/,\n/g'
foo,
bar,
baz

MacOS is different, there is two way to solve this problem with sed in mac

first ,use \'$'\n'' replace \n, it can work in MacOS: sed 's/,/\'$'\n''/g' file

the second, just use an empty line: sed 's/,/\ /g' file

Ps. Pay attention the range separated by '

the third, use gnu-sed replace the mac-sed

Apparently \r is the key!

$ sed 's/, /\r/g' file3.txt > file4.txt

Transformed this:

ABFS, AIRM, AMED, BOSC, CALI, ECPG, FRGI, GERN, GTIV, HSON, IQNT, JRCC, LTRE,
MACK, MIDD, NKTR, NPSP, PME, PTIX, REFR, RSOL, UBNT, UPI, YONG, ZEUS

To this:

ABFS
AIRM
AMED
BOSC
CALI
ECPG
FRGI
GERN
GTIV
HSON
IQNT
JRCC
LTRE
MACK
MIDD
NKTR
NPSP
PME
PTIX
REFR
RSOL
UBNT
UPI
YONG
ZEUS

This works on MacOS Mountain Lion (10.8), Solaris 10 (SunOS 5.10) and RHE Linux (Red Hat Enterprise Linux Server release 5.3, Tikanga)...

$ sed 's/{pattern}/\^J/g' foo.txt > foo2.txt

... where the ^J is done by doing ctrl+v+j. Do mind the \ before the ^J.

PS, I know the sed in RHEL is GNU, the MacOS sed is FreeBSD based, and although I'm not sure about the Solaris sed, I believe this will work pretty much with any sed. YMMV tho'...

To make it complete, this also works:

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

Though I am late to this post, just updating my findings. This answer is only for Mac OS X.

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

In the above command I tried with Shift+Enter to add new line which didn't work. So this time I tried with "escaping" the "unescaped newline" as told by the error.

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

Worked! (in Mac OS X 10.9.3)

$ echo $PATH | sed -e $'s/:/\\\n/g' 
/usr/local/sbin
/Library/Oracle/instantclient_11_2/sdk
/usr/local/bin

...

Works for me on Mojave

Just to clearify: man-page of sed on OSX (10.8; Darwin Kernel Version 12.4.0) says:

[...]

Sed Regular Expressions

 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.

[...]

so I guess one have to use tr - as mentioned above - or the nifty

sed "s/,/^M
/g"

note: you have to type -v, to get '^M' in vi editor

The sed on macOS Mojave was released in 2005, so one solution is to install the gnu-sed,

brew install gnu-sed

then use gsed will do as you wish,

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

If you prefer sed, just sudo sh -c 'echo /usr/local/opt/gnu-sed/libexec/gnubin > /etc/paths.d/brew', which is suggested by brew info gnu-sed. Restart your term, then your sed in command line is gsed.

FWIW, the following line works in windows and replaces semicolons in my path variables with a newline. I'm using the tools installed under my git bin directory.

echo %path% | sed -e $'s/;/\\n/g' | less

I have found another command that is working also.

find your_filename.txt -type f -exec sed -i 's/,/\n/g' {} \;