Google strips most special characters from the text they index so it's not a good tool for many troubleshooting-related tasks, such as finding out what the variable "$-" is in perl, or searching for error output that is loaded with special characters.
Is there a good way to search for such content on the web?
This question is related to the following question: Looking for special characters in Google
This search engine was made to solve exactly the kind of problem you're having: http://symbolhound.com/
I am the developer of SymbolHound.
Unfortunately, there doesn't appear to be a magic bullet. Bottom line up front: "context".
Google indeed ignores most punctuation, with the following exceptions:
- Punctuation in popular terms that have particular meanings, like [ C++ ] or [ C# ] (both are names of programming languages), are not ignored.
- The dollar sign ($) is used to indicate prices. [ nikon 400 ] and [ nikon $400 ] will give different results.
- The hyphen - is sometimes used as a signal that the two words around it are very strongly connected. (Unless there is no space after the - and a space before it, in which case it is a negative sign.)
- The underscore symbol _ is not ignored when it connects two words, e.g. [ quick_sort ].
As such, it is not well suited for these types of searchs. Google Code however does have syntax for searching through their code projects, that includes a robust language/syntax for dealing with "special characters". If looking at someone else's code could help solve a problem, this may be an option.
Unfortunately, this is not a limitation unique to google. You may find that your best successes hinge on providing as much 'context' to the problem as possible. If you are searching to find what $- means, providing information about the problem's domain may yield good results.
For example, searching "special perl variables" quickly yields your answer in the first entry on the results page.
A great search engine for special characters that I recenetly found: amp-what?
You can even search by object name, like "arrow", "chess", etc...
duckduckgo.com doesn't ignore special characters, at least if the whole string is between ""
https://duckduckgo.com/?q=%22*222%23%22
来源：https://stackoverflow.com/questions/4685615/how-can-i-use-a-search-engine-to-search-for-special-characters