[Help-nano] Look ahead on sh.nanorc

[Jose Antonio Velasco]

Hi everybody,

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.

Best regards,

Jose