sed: change the linebreak before a specific patern to a space

Question

I would like to use sed to change a line breaks preceding a specific character and replace it with a simple space:

Example:

<link rel="colorSchemeMapping
"
href="marinedrugs-790193-original.fld/colorschememapping.xml">

Should be:

<link rel="colorSchemeMapping" href="marinedrugs-790193-original.fld/colorschememapping.xml">

I'm aware of the

':a;N;$!ba;s/\n/ /g'

but am willing to add the double quotes as being mandatory preceding the line break.

Thanks @WiktorStribiżew! I am trying to run this in a shell script and is somehow not working. I will try to figure it out... — Milos Cuculovic, Jul 09 '20 at 11:54
Do you want to update files inline? `sed -i -E ':a;N;$!ba;s/\n(")\n|\n/\1 /g' file`? — Wiktor Stribiżew, Jul 09 '20 at 11:54
@WiktorStribiżew, I'm trying this way `sed -i -E ':a;N;$!ba;s/\n(")\n|\n/\1 /g' "$1"` and nothing happens, I'm missing something... Is there a way not tu use -E? — Milos Cuculovic, Jul 09 '20 at 12:05
So weird. This for example works perfectly well for another sed `sed -i 's@content=$[^"][^ >]*$@content="\1"@' "$1"`, however, the example you gave me is simply doing nothing for some reason :( — Milos Cuculovic, Jul 09 '20 at 12:34
Try `sed ':a;N;$!ba;s/\n"\n/" /g; s/\n/ /g'` or `sed -e ':a;N;$!ba' -e 's/\n"\n/" /g' -e 's/\n/ /g'` — Wiktor Stribiżew, Jul 09 '20 at 12:47
may be you have dos style line endings? does `cat -v file` show `^M` at end of lines? — Sundeep, Jul 09 '20 at 13:19
See [Why does my tool output overwrite itself and how do I fix it?](https://stackoverflow.com/questions/45772525/why-does-my-tool-output-overwrite-itself-and-how-do-i-fix-it) — Sundeep, Jul 09 '20 at 13:30
Then you need `sed ':a;N;$!ba;s/\r\n"\r\n/" /g; s/\r\n/ /g'` or `sed -e ':a;N;$!ba' -e 's/\r\n"\r\n/" /g' -e 's/\r\n/ /g'` — Wiktor Stribiżew, Jul 09 '20 at 14:23

Wiktor Stribiżew · Accepted Answer · 2020-07-09T14:25:20.193

I suggest replacing newline+"+newline with the " and space, and any other newline with a space:

sed -i -E ':a;N;$!ba;s/\n(")\n|\n/\1 /g' file
sed -i ':a;N;$!ba;s/\n"\n/" /g; s/\n/ /g' file

or

sed -e ':a;N;$!ba' -e 's/\n"\n/" /g' -e 's/\n/ /g' file > newfile

LINE ENDING NOTE: If your endings are CRLF, you need to replace \n with \r\n in the above patterns.

Note -E will enable POSIX ERE syntax (to avoid using too many backslashes in the pattern). The regex means

\n(")\n - a newline, then " is captured into Group 1 and then a newline
| - or
\n - a newline.

The replacement is Group 1 value (" if it was matched) and a space.

See the online sed demo:

s='<link rel="colorSchemeMapping
"
href="marinedrugs-790193-original.fld/colorschememapping.xml">'
sed -E ':a;N;$!ba;s/\n(")\n|\n/\1 /g' <<< "$s"
# => <link rel="colorSchemeMapping" href="marinedrugs-790193-original.fld/colorschememapping.xml">

Thank you Wiktor, I was managed to make this working by using: `sed -i -E ':a;N;$!ba;s/(")\n/\1 /g' "$1"` — Milos Cuculovic, Jul 10 '20 at 14:31

Ed Morton · Answer 2 · 2020-07-09T13:27:00.497

2

Since you're using GNU sed anyway:

$ sed -z 's/\n"\n/" /g' file
<link rel="colorSchemeMapping" href="marinedrugs-790193-original.fld/colorschememapping.xml">

If you find yourself using constructs other than s, g, and p (with -n) in sed then you're using the wrong tool and should instead be using awk or similar. All other sed constructs became obsolete 40+ years ago when awk was invented.

edited Jul 09 '20 at 13:27

answered Jul 09 '20 at 13:21

Ed Morton

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sed: change the linebreak before a specific patern to a space

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