For questions about the POSIX select() system call and its close relative pselect(), and also the functions to manipulate FD sets (FD_CLR, FD_ISSET, FD_SET, FD_ZERO). The select() calls are used to determine whether read or write operations can be made on specified file descriptors without blocking, or if there are error conditions on specified file descriptors. You can also ask about platform-specific variants with this tag.
