Type ‘make install’ as a user with the appropriate privileges (e.g., ‘bin’ or perhaps even ‘root’).
Type ‘cd /usr/include; mkid’ to build an ID database covering all of the system header files.
Type ‘lid FILE’, then ‘gid strtok’, then ‘aid stdout’.
You have just built, installed and used the most common commands of the GNU ID utilities. If you ever need help remembering which system header files contain a particular declaration, or reference a particular symbol, you'll want to keep the ID file you built in /usr/include for later use. If your working directory is elsewhere at the time, simply provide the ‘-f /usr/include’ option to lid (see Reading options).