rgrep default files pattern

Question

How can I modify the default FILES pattern in rgrep for C++ mode?

For C mode the default is *.[ch]. For C++, it is *.cc *.cxx *.cpp *.C *.CC *.c++.

I would like to change it to *.cc *.[ch]xx *.[ch]pp *.[CHh] *.CC *.HH *.[ch]++.

Answer 1

M-xcustomize-variableRETgrep-files-aliases and then use the interface to change the value of this variable.

Alternatively, you could put:

(setf (cdr (assoc "cc" grep-files-aliases))
      (assoc "cchh" grep-files-aliases))

For future reference, you could have looked up the help for rgrep (by typing C-h frgrep) where it says:

Recursively grep for REGEXP in FILES in directory tree rooted at DIR. The search is limited to file names matching shell pattern FILES. FILES may use abbreviations defined in grep-files-aliases, e.g. entering ch is equivalent to *.[ch].