ftok Convert a pathname and a project identifier to a System V IPC key &reftitle.description; intftok stringfilename stringproject_id The function converts the filename of an existing accessible file and a project identifier into an integer for use with for example shmop_open and other System V IPC keys. &reftitle.parameters; filename Path to an accessible file. project_id Project identifier. This must be a one character string. &reftitle.returnvalues; On success the return value will be the created key value, otherwise -1 is returned. &reftitle.seealso; shmop_open sem_get