ftok Convert a pathname and a project identifier to a System V IPC key intftok stringpathname stringproj The function converts the pathname of an existing accessible file and a project identifier (proj) into a integer for use with for example shmop_open and other System V IPC keys. The proj parameter should be a one character string. On success the return value will be the created key value, otherwise -1 is returned. See also shmop_open and sem_get.