[regex] How to match any non white space character except a particular one?

On my system: CentOS 5

I can use \s outside of collections but have to use [:space:] inside of collections. In fact I can use [:space:] only inside collections. So to match a single space using this I have to use [[:space:]] Which is really strange.

echo a b cX | sed -r "s/(a\sb[[:space:]]c[^[:space:]])/Result: \1/"

Result: a b cX
  • first space I match with \s
  • second space I match alternatively with [[:space:]]
  • the X I match with "all but no space" [^[:space:]]

These two will not work:

a[:space:]b  instead use a\sb or a[[:space:]]b

a[^\s]b      instead use a[^[:space:]]b