Removing extra space form a string

[imranka]

Problem: Suppose I have a string like

This is ~~~~~a ~~~~~test ~~~~~string

I want to remove the extra space but keep intact the single space between two words. Like this:

This is a test string

I achieved this using java, but I smell that this is uncool because a linux guru will come with a single line of sed or awk or whatever that exactly do the same thing but in a much smarter way. Any help?

EDIT: please read ~ as single space, I couldn't put extra spaces between words as the editor is formatting the text with intelligence which certainly not going to help me in this case.

[scm]

It's not clear to me where your extra space is but if it's at the end of the line the command

sed 's/ *$//'

will remove all trailing spaces. Unpicking it it's saying to replace with nothing (the // at the end) any pattern consisting of zero or more spaces (the " *") followed by end of line (the $).

[imranka]

Oh, so quick a reply. Thanks scm.

As I said, in this editor its not possible to write a string with extra spaces, as it trims that automatically, so you kindly read the first string with ~ replaced with space. Hope this is clear.

[wje_lf]

Um, imranka, did you come away from scm's response with a sufficient answer to your question? I couldn't tell one way or the other by reading your response.

But if you need to remove trailing spaces, but also need to replace multiple spaces inside a string with a single space, try this:

sed -e 's/~~*/~/g' -e 's/~*/$/'

and if you don't want to remove trailing spaces, this will suffice:

sed 's/~~*/~/g'

I've adopted your convention of using "~" to mean "space".

Hope this helps.

[scm]

But if you need to remove trailing spaces, but also need to replace multiple spaces inside a string with a single space, try this:

sed -e 's/~~*/~/g' -e 's/~*/$/'

I think you've transposed a couple characters, Bill!

sed -e 's/~~*/~/g' -e 's/~*$//'

[imranka]

I think you've transposed a couple characters, Bill!

sed -e 's/~~*/~/g' -e 's/~*$//'

This is great. Thanks scm and Bill. The first solution scm offered would not work as I was not concerned with trailing space, rather the extra spaces between two characters. So, modifying above sed as(replacing '~' with ' ') :

sed -e 's/ */ /g' -e 's/ *$//'

worked perfectly.
Thanks once again.

[wje_lf]

I think you've transposed a couple characters, Bill!

Never happen. I'm too old to make mistakes.

[ghostdog74]

# echo "This is      a     test  string" |awk '{$1=$1}1' OFS=" "
This is a test string

[radoulov]

$ set --  This is      a     test  string;echo "$@"
This is a test string

With bash/ksh93 arrays:

s="This is      a     test  string"
s=($s)
$ echo "$@"
This is a test string

With tr:

$ tr -s \  <<<'This is      a     test  string'
This is a test string

With Awk this should be sufficient:

$ awk '$1=$1' <<<'This is      a     test  string'
This is a test string

[imranka]

Thanks to all,
I must say I'm now overwhelmed with choice