operating system services closerange(lowhighcloses all file descriptors fd in the range low <fd high errors are ignored dup(fdduplicates file descriptor fd returns new file descriptor that' the lowest-numbered unused file descriptor for the process the new and old file descriptors can be used interchangeably furthermorethey share statesuch as the current file pointer and locks (unix and windowsdup (oldfdnewfdduplicates file descriptor oldfd to newfd if newfd already corresponds to valid file descriptorit' closed first (unix and windowsfchmod(fdmodechanges the mode of the file associated with fd to mode see the description of os open(for description of mode (unixfchown(fduidgidchanges the owner and group id of the file associated with fd to uid and gid use valid of - for uid or gid to keep the value unchanged (unixfdatasync(fdforces all cached data written to fd to be flushed to disk (unixfdopen(fd [mode [bufsize]]creates an open file object connected to file descriptor fd the mode and bufsize arguments have the same meaning as in the built-in open(function mode should be string such as ' '' 'or 'aon python this function accepts any additional parameters that work with the built-in open(function such as specifications for the encoding and line ending howeverif portability with python is concernyou should only use the mode and bufsize arguments described here fpathconf(fdnamereturns configurable pathname variables associated with the open file with descriptor fd name is string that specifies the name of the value to retrieve the values are usually taken from parameters contained in system header files such as and posix defines the following constants for nameconstant description "pc_async_ioindicates whether asynchronous / can be performed on fd indicates whether the chown(function can be used if fd refers to directorythis applies to all files in the directory maximum size of file maximum value of the file' link count maximum length of formatted input line fd refers to terminal maximum length of an input line fd refers to terminal "pc_chown_restricted"pc_filesizebits"pc_link_max"pc_max_canon"pc_max_inputf lib fl ff