os.path.commonprefix(list) Return the longest path prefix (taken character-by-character) that is a prefix of all paths in list. If list is empty, return the empty string (''). Note This function may return invalid paths because it works a character at a time. To obtain a valid path, see commonpath(). >>> os.path.commonprefix(['/usr/lib', '/usr/local/lib']) '/usr/l' >>> os.path.commonpath(['/usr/lib', '/usr/local/lib']) '/usr'

os.path.commonpath(paths) Return the longest common sub-path of each pathname in the sequence paths. Raise ValueError if paths contains both absolute and relative pathnames, or if paths is empty. Unlike commonprefix(), this returns a valid path. Availability: Unix, Windows New in version 3.5.

os.path.basename(path) Return the base name of pathname path. This is the second element of the pair returned by passing path to the function split(). Note that the result of this function is different from the Unix basename program; where basename for '/foo/bar/' returns 'bar', the basename() function returns an empty string ('').

os.path.abspath(path) Return a normalized absolutized version of the pathname path. On most platforms, this is equivalent to calling the function normpath() as follows: normpath(join(os.getcwd(), path)).

os.pardir The constant string used by the operating system to refer to the parent directory. This is '..' for Windows and POSIX. Also available via os.path.

os.openpty() Open a new pseudo-terminal pair. Return a pair of file descriptors (master, slave) for the pty and the tty, respectively. The new file descriptors are non-inheritable. For a (slightly) more portable approach, use the pty module. Availability: some flavors of Unix. Changed in version 3.4: The new file descriptors are now non-inheritable.

os.open(path, flags, mode=0o777, *, dir_fd=None) Open the file path and set various flags according to flags and possibly its mode according to mode. When computing mode, the current umask value is first masked out. Return the file descriptor for the newly opened file. The new file descriptor is non-inheritable. For a description of the flag and mode values, see the C run-time documentation; flag constants (like O_RDONLY and O_WRONLY) are defined in the os module. In particular, on Windows a

os.nice(increment) Add increment to the process’s “niceness”. Return the new niceness. Availability: Unix.

os.name The name of the operating system dependent module imported. The following names have currently been registered: 'posix', 'nt', 'ce', 'java'. See also sys.platform has a finer granularity. os.uname() gives system-dependent version information. The platform module provides detailed checks for the system’s identity.

os.mknod(path, mode=0o600, device=0, *, dir_fd=None) Create a filesystem node (file, device special file or named pipe) named path. mode specifies both the permissions to use and the type of node to be created, being combined (bitwise OR) with one of stat.S_IFREG, stat.S_IFCHR, stat.S_IFBLK, and stat.S_IFIFO (those constants are available in stat). For stat.S_IFCHR and stat.S_IFBLK, device defines the newly created device special file (probably using os.makedev()), otherwise it is ignored. T