Norihiro Tanaka <[email protected]> writes: >> grep 2.5.4 has an undocumented \S operator: > > It means it doesn't be supported by grep 2.5.4. > > Grep 2.5.4 uses regex, which is included in GNU libc and supports > `\S' operand. However, Grep 2.5.4 also use own engines, which can't > interpret `\S' operand. So you mayn't use undocumented operands.
Many people use \| \( etc. to turn off the magic properties of a character, just in case there are magic properties. That is because "backslash something" matches just "something", unless "something" is magic. (Please also mention that on the man page.) And all magic things are documented on the man page. So \S matching other than S is a bug! Unless you declare it otherwise on the man page.
