[regex] grep regex whitespace behavior

I have a textfile, containing something like:

12,34 EUR 
 5,67 EUR

There is one whitespace before 'EUR' and I ignore 0,XX EUR.

I tried:

grep '[1-9][0-9]*,[0-9]\{2\}\sEUR' => didn't match !

grep '[1-9][0-9]*,[0-9]\{2\} EUR' => worked !

grep '[1-9][0-9]*,[0-9]\{2\}\s*EUR' => worked !

grep '[1-9][0-9]*,[0-9]\{2\}\s[E]UR' => worked !

Can somebody explain me pls, why I can't use \s but \s* and \s[E] matched?

OS: Ubuntu 10.04, grep v2.5

This question is related to regex grep gnu

The answer is

This looks like a behavior difference in the handling of \s between grep 2.5 and newer versions (a bug in old grep?). I confirm your result with grep 2.5.4, but all four of your greps do work when using grep 2.6.3 (Ubuntu 10.10).


GNU grep 2.5.4
echo "foo bar" | grep "\s"
   (doesn't match)


GNU grep 2.6.3
echo "foo bar" | grep "\s"
foo bar

Probably less trouble (as \s is not documented):

Both GNU greps
echo "foo bar" | grep "[[:space:]]"
foo bar

My advice is to avoid using \s ... use [ \t]* or [[:space:]] or something like it instead.

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