(How) can I remove all newlines (\n) using sed?

I tried to remove all newlines in a pipe like this:

(echo foo; echo bar) | sed -e :a -e N -e '$!ba' -e 's/\n/ /g' | hexdump -C

Which results on debian squeeze in:

00000000  66 6f 6f 20 62 61 72 0a                           |foo bar.|
00000008

Not removing the trailing newline.

开发者_运维百科

tr -d '\n' as in How do I remove newlines from a text file? works just fine but isn't sed.

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Sorry can't be done using sed, please see: http://sed.sourceforge.net/sedfaq5.html#s5.10 and a discussion here: http://objectmix.com/awk/26812-sed-remove-last-new-line-2.html

Looks like sed will add back the \n if it is present as the last character.

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you need to replace \n with something else, instead of removing it. and because lines are seperated by \n (at least on GNU/Linux) you need to tell sed to look for some other EOL character using -z, like so:

> echo -e "remove\nnew\nline\ncharacter" | sed -z "s/\n//g"
removenewlinecharacter> 

From sed --help

  -z, --null-data
                 separate lines by NUL characters

sed would normally remove entire lines (using /d), like so:

> echo -e "remove\nnew\nline\ncharacter" | sed "/rem\|char/d"
new
line
> echo -e "remove\nnew\nline\ncharacter" | sed -r "/rem|char/d"
new
line
>

using /d every line containing an EOL would be deleted, which are all lines. (one)

> echo -e "remove\nnew\nline\ncharacter" | sed -z "/\n/d"
> 

HTH

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If you want to remove the last \n you need an external utility, or use e.g. awk.

printf "%s" `(echo foo; echo bar) | sed -e :a -e N -e '$!ba' -e 's/\n/ /g'`

should work.

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{ echo foo; echo bar; } | awk '{printf("%s ", $0)}' 

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Compare: (echo foo; echo bar) | sed -e :a -e N -e '$!ba' -e 's/\n/ /g' | hexdump -C with (echo foo; echo bar) |tr -d '\n' | hexdump -C and then with echo foo; echo bar) | hexdump -C | sed -e :a -e N -e '$!ba' -e 's/\n/ /g'

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If foo and bar are not expected to contain new lines, then you must beware that

(echo foo; echo bar)

will add a new line after each echo

(echo -n foo; echo -n bar)

will not add a new line at the end of the output. So it may be that you don't need sed to remove new lines at all even if it did remove the trailing lines.

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The answer of Stefan Kaerst is perfect:

(echo foo; echo bar) | sed -z "s/\n//g" 

This will export "foobar", as the parameter -z, --null-data separates end of lines by NUL characters (even thought there are no nulls in the text: foobar="66 6f 6f 62 61 72").

An useful example

I use this command to restore paragraphs with broken lines:

cat novel.txt | sed -r 's/^(.{53,80})$/\1<br>/;' | sed -z "s/<br>\n//g" 

This joints long lines if they are longer then 53 characters.

A) Find lines longer then 53 characters and add '<br>' at their end.

B) Find '<br>' with newline and remove it.

Thank you, Mr. Kaerst!

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you can also try :

(echo foo; echo bar) | sed 's/\n//' | xargs echo -n