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How can I replace all newlines with space except the last newline. I can replace all newline to space using tr but how I can do it with some exceptions?

Gilles 'SO- stop being evil'
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    `sed -z 's/\n/ /g; s/.$//'` - assuming "the last" newline is at the end of the stream (what you probably mean) – bloody Mar 31 '23 at 08:12

6 Answers6

63

You can use paste -s -d ' ' file.txt:

$ cat file.txt
one line
another line
third line
fourth line

$ paste -s -d ' ' file.txt 
one line another line third line fourth line
grebneke
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18

You can use tr to replace all newlines to space and pass the output to sed and replace the last space back to a newline:

tr '\n' ' ' < afile.txt | sed '$s/ $/\n/'
X Tian
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Ketan Maheshwari
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7

Re-implementing vonbrand's idea in Perl, provided the file is small enough:

perl -p00e 's/\n(?!\Z)/ /g' your_file
Community
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Joseph R.
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  • +1 because this method works for replacements with _multibyte characters_ (as opposed to GNU paste) – myrdd Dec 21 '18 at 16:27
-1

This worked for me.

tr '\n' ' ' < file_with_new_line   | sed 's/\ $//g' > file_with_space
Abhijit
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  • That will remove the last newline as well. – terdon Feb 29 '16 at 08:58
  • I don't think so, it is working fine. Have you really tried it??? – Abhijit Mar 01 '16 at 11:20
  • Yes I have. Have you? Your `tr` command replaces _all_ newlines with spaces and your `sed` command removes the last space. This results in a file without a final newline and so is not what the question is asking for. By the way, there's no point int using `g` in the `sed` command. Since you're using `$`, it can only match at the end, the `g` is pointless. You also don't need to escape the space, the `\` makes no difference either. – terdon Mar 01 '16 at 12:14
-1

you can use this trick: echo $(cat file.txt)

mrash
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  • Not if there are multiple (adjacent) spaces, or empty or all-space lines, or any word in the file contains shell 'glob' characters/constructs (`* ? [..]`) that match any file(s) in the current directory, or depending on your shell sometimes even if they don't match. Or if the file size exceeds approximately ARG_MAX on shells where `echo` isn't builtin. – dave_thompson_085 Jul 05 '21 at 05:29
-2

Something like sed -e 's;\n\(.\); \1;' should do...

vonbrand
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