Shell Programming and Scripting

\s stands for �whitespace character��. Again, which characters this actually includes, depends on the regex flavor. In all flavors discussed in this tutorial, it includes [ \t\r\n\f]. That is: \s matches a space, a tab, a line break, or a form feed. Most flavors also include the vertical tab, with Perl (prior to version 5.18) and PCRE (prior to version 8.34) being notable exceptions. In flavors that support Unicode, \s normally includes all characters from the Unicode �separator�� category. Java and PCRE are exceptions once again. But JavaScript does match all Unicode whitespace with \s.

Originally Posted by blackrageous

Anybody have an explanation for why \s doesn't match ' ' in a character class? Here are 3 examples with the final example showing that \s in a character class (demonstrated by using egrep -o) fails:

\s works outside of class..

Code:

# echo " FOO " | egrep -o '\s[A-Z]+\s'
 FOO

Here is a sanity check using ' '...

Code:

# echo " FOO " | egrep -o '[  ][A-Z]+[  ]'
 FOO

Here I try with \s in a character class

Code:

# echo " FOO " | egrep -o '[\s][A-Z]+[\s]'
#

Originally Posted by Neo

Also, another FWIW:

Code:

linux# php -a
Interactive mode enabled

php > $a = ' FOO ';
php > echo preg_match('/[\s][A-Z]+[\s]/', $a,$matches);
1
php > echo $matches[0];
 FOO 
php >

so, it works in a PHP REGEX .....