Trying to print "\n" in bash with sed

Question

Having some problems having sed insert the two-character sequence \n. (I'm using bash to create some expect scripts). Anything that I try in a replace pattern ends up as an actual newline character.

I've tried:

sed s/<string>/'\\\\n'/
sed s/<string>/\\\\n/
sed s/<string>/\\n/

And pretty much any permutation that does or doesn't make any sense.

I need it to work with the bash and sed installed on a Mac.

Which version of `sed`? The GNU and bsd versions process escape sequences quite a bit differently, and I'm not sure about others... — Gordon Davisson, Sep 24 '15 at 02:53
duplicate of http://stackoverflow.com/questions/723157/how-to-insert-a-newline-in-front-of-a-pattern — ergonaut, Sep 24 '15 at 02:55
@ergonaut This isn't a dup, it's the opposite of that question. — Gordon Davisson, Sep 24 '15 at 02:57
how is it the opposite? The other question's answer points to the same answer stated by @chepner. — ergonaut, Sep 24 '15 at 03:02
@ergonaut That's not what the current question asks for -- it asks for a backslash followed by "n" in the output, rather than a linefeed. The other question is about getting a linefeed instead of backslash and "n". — Gordon Davisson, Sep 24 '15 at 03:03

Gordon Davisson · Answer 1 · 2015-09-24T03:11:28.657

sed s/<string>/'\\n'/ works for me with both the Lunix (GNU) and OS X (bsd) versions of sed:

$ echo aXb | sed s/X/'\\n'/
a\nb

sed s/<string>/\\\\n/ would also work. When bash sees \\ (outside of quotes), it treats it as a single escaped backslash, so \ is actually passed to the command. When it sees \\\\n, that's just two escaped backslashes followed by "n", so it passes \\n to the command. Then, when sed sees \\n, it also treats that as an escaped backslash followed by "n", so the replacement string winds up being \n. Since the "n" is always after any completed escape sequence, it's just treated as another character in the replacement string.

for me `echo 122 | sed 's/2/\\n/g'` works on AIX, SUN, RHEL – Mahesh Kharvi Sep 24 '15 at 05:46 — Mahesh Kharvi, Sep 24 '15 at 05:46

NeronLeVelu · Answer 2 · 2015-09-24T08:08:45.173

0

pure code, single quoted

sed 's/Pattern/\\n/' YourFile

Shell interpreted, double quote

sed "s/Pattern/\\\\n/" YourFile

edited Sep 24 '15 at 08:08

answered Sep 24 '15 at 05:45

NeronLeVelu

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OP doesn't want a newline. What is wanted is literally a backslash followed by an n. – rici Sep 24 '15 at 06:02
oops :-) i will adapt, sorry – NeronLeVelu Sep 24 '15 at 08:05

Trying to print "\n" in bash with sed

2 Answers2