I'd like to know if there's a way I can use look ahead on a regex in sh.nanorc file. When I try to use
color brightred "^[[:alpha:]_][[:alnum:]_]*(?==)"
I get the following error
Error in /usr/share/nano/sh.nanorc on line 19: Bad regex "^[[:alpha:]_][[:alnum:]_]*(?==)": Invalid preceding regular _expression_
Thanks in advance for your kindly help.