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I am new to shell scripting and i am trying to remove new line character from each line using SED. this is what i have done so far :

printf "{new\nto\nlinux}" | sed ':a;N;s/\n/ /g'

removes only Ist new line character. I somewhere found this command :

printf "{new\nto\nlinux}" | sed ':a;N;$!ba;s/\n/ /g'

but it gives :"ba: Event not found."

if i do:

printf "{new\nto\nlinux}" | sed ':a;N;s/\n/ /g' | sed ':a;N;s/\n/ /g'

then it gives correct output but i am looking for something better as i am not sure how many new character i will get when i run the script. incoming stream is from echo or printf or some variable in script. Thanks in advance

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98

To remove newlines, use tr:

tr -d '\n'

If you want to replace each newline with a single space:

tr '\n' ' '

The error ba: Event not found is coming from csh, and is due to csh trying to match !ba in your history list. You can escape the ! and write the command:

sed ':a;N;$\!ba;s/\n/ /g'  # Suitable for csh only!!

but sed is the wrong tool for this, and you would be better off using a shell that handles quoted strings more reasonably. That is, stop using csh and start using bash.

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  • thanks for your reply but you can we use tr with to modify incoming stream from echo or printf??
    – nav_jan
    May 16 '12 at 12:48
  • Nope, this still does not work. Even with the $\!ba, the result is ba: Event not found from a csh script.
    – krb686
    May 21 '15 at 14:11
  • The answer should be sed ':a;N;$\\!ba;s/\n/ /g'
    – krb686
    May 21 '15 at 14:12
  • I wanted to replace some but not all newlines in a file. e.g. all lines ending with PULLUP. This worked: sed ':a;N;$!ba;s/PULLUP\n/ /g;'.
    – gaoithe
    Sep 10 '15 at 11:32
6

This might work for you:

printf "{new\nto\nlinux}" | paste -sd' '            
{new to linux}

or:

printf "{new\nto\nlinux}" | tr '\n' ' '            
{new to linux}

or:

printf "{new\nto\nlinux}" |sed -e ':a' -e '$!{' -e 'N' -e 'ba' -e '}' -e 's/\n/ /g'
{new to linux}
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0

Use perl instead of sed. perl is similar to sed:

ubuntu@ubuntu:/$ printf "{new\nto\nlinux}" | sed 's/\n/ /g'; echo ''
{new
to
linux}
ubuntu@ubuntu:/$ printf "{new\nto\nlinux}" | perl -pe 's/\n/ /g'; echo ''
{new to linux}
ubuntu@ubuntu:/$ echo -e "new\nto\nlinux\ntest\n1\n2 3" | perl -pe 's/\n/_ _/g'; echo ''
new_ _to_ _linux_ _test_ _1_ _2 3_ _
ubuntu@ubuntu:/$
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