Question

I am trying the following query, but without success

    grep -nr "[[:alnum:]]+\.[[:alnum:]]+\(\)" .

So, according to my logic, a method call would be one or more alphanumeric characters

   [[:alnum:]]+

followed by a dot

   \. 

followed by one or more alphanumeric characters

    [[:alnum:]]+

followed by paranthesis (for void return type only)

    \(\)

But this query isn’t working. How to write such a query?

Answer 1

grep provides several types of regex syntax.
Your pattern is written is the extended syntax and works with -E
extended-regexp has an easier/better syntax, and perl-regexp is, well, quite powerful.

• -E, –extended-regexp
• -F, –fixed-strings
• -G, –basic-regexp (the default)
• -P, –perl-regexp

---

grep -nrE "[[:alnum:]]+\.[[:alnum:]]+\(\)" .