Python note-1, python note

Python note-1, python note

OS module Description: the python OS module contains common operating system functions.

OS. access (path, mode) # verify the permission mode
OS. chdir (path) # change the current working directory
OS. chflags (path, flags) # set the path tag as a number tag.
OS. chmod (path, mode) # Change permissions
OS. chown (path, uid, gid) # change the file owner
OS. chroot (path) # change the root directory of the current process
OS. close (fd) # disable file descriptor fd
OS. closerange (fd_low, fd_high) # Close all file descriptors, from fd_low (included) to fd_high (not included). The error will be ignored.
OS. curdir # the current directory is returned :('.')
OS. dup (fd) # copy the file descriptor fd
OS. dup2 (fd, fd2) # copy one file descriptor fd to another fd2
OS. environ # obtain system environment variables
OS. fchdir (fd) # change the current working directory through the file descriptor
OS. fchmod (fd, mode) # change the access permission of a file. The file is specified by the fd parameter, and the mode parameter is the file access permission under Unix.
OS. fchown (fd, uid, gid) # modify the ownership of a file. This function modifies the user ID and user group ID of a file, which is specified by the file descriptor fd.
OS. fdatasync (fd) # forcibly write the file to the disk. The file is specified by the file descriptor fd, but the file status information is not forcibly updated.
OS. fdopen (fd [, mode [, bufsize]) # create a file object through the file descriptor fd and return this file object
OS. fpathconf (fd, name) # Return the system configuration information of an opened file. Name is the value of the retrieved system configuration. It may be a string that defines the system value. These names are specified in many standards (POSIX.1, Unix 95, Unix 98, and others ).
OS. fstat (fd) # returns the state of the file descriptor fd, such as stat ().
OS. fstatvfs (fd) # returns information about the file system that contains the file descriptor fd, such as statvfs ()
OS. fsync (fd) # forcibly write the file with the file descriptor fd to the hard disk.
OS. ftruncate (fd, length) # crop the file corresponding to the file descriptor fd, so it cannot exceed the file size.
OS. getcwd () # Return to the current working directory
OS. getcwdu () # returns the Unicode object of the current working directory.
OS. isatty (fd) # If the file descriptor fd is open and connected to the tty (-like) device, true is returned; otherwise, False is returned.
OS. lchflags (path, flags) # mark the path as a number, similar to chflags (), but there is no soft link
OS. lchmod (path, mode) # modify the connection File Permission
OS. lchown (path, uid, gid) # change the file owner, similar to chown, but do not trace the link.
OS. link (src, dst) # create a hard link named dst, pointing to the src Parameter
OS. listdir (path) # Return the list of files or folder names in the folder specified by path.
OS. lseek (fd, pos, how) # set the current position of the file descriptor fd to pos. how to modify it: SEEK_SET or 0 to set the pos calculated from the file; SEEK_CUR or 1 is calculated from the current location; OS. SEEK_END or 2 starts from the end of the file. valid in unix and Windows
OS. lstat (path) # Like stat (), but there is no soft link
OS. linesep # The row Terminator used by the current platform. It is \ t \ n in win and \ n in Linux"
OS. major (device) # extract the device major number from the original device number (use st_dev or st_rdev field in stat ).
OS. makedev (major, minor) # Use the major and minor device numbers to form an original device number.
OS. makedirs (path [, mode]) # recursive Folder creation function. For example, mkdir (), but all the created intermediate-level folders must contain subfolders.
OS. minor (device) # extract the device minor number from the original device number (use st_dev or st_rdev field in stat ).
OS. mkdir (path [, mode]) # create a folder named path in the mode of the number. The default mode is 0777 (octal ).
OS. mkfifo (path [, mode]) # create a named pipe. The mode is a number and the default value is 0666 (octal)
OS. mknod (filename [, mode = 0600, device]) # create a file system node named filename (file, device special file, or pipe ).
OS. open (file, flags [, mode]) # open a file and set the required open options. The mode parameter is optional.
OS. openpty () # open a new Pseudo Terminal Pair. Returns the pty and tty file descriptors.
OS. pathconf (path, name) # Return the system configuration information of the relevant file.
OS. pathsep # string used to split the file path
OS. pardir # obtain the string name of the parent directory of the current directory :('..')
OS. pipe () # create a pipeline. A pair of file descriptors (r, w) are returned for reading and writing respectively.
OS. popen (command [, mode [, bufsize]) # open a pipeline from a command
OS. path. abspath (path) # returns the absolute path of path normalization.
OS. path. split (path) # splits the path into two groups of directories and file names.
OS. path. dirname (path) # Return the path directory. It is actually the first element of OS. path. split (path ).
OS. path. basename (path) # Return the final file name of the path. If the path ends with a slash (/) or slash (\), a null value is returned. That is, the second element of OS. path. split (path ).
OS. path. exists (path) # True is returned if path exists. False is returned if path does not exist.
OS. path. isabs (path) # If path is an absolute path, True is returned.
OS. path. isfile (path) # If path is an existing file, True is returned. Otherwise, False is returned.
OS. path. isdir (path) # If path is an existing Directory, True is returned. Otherwise, False is returned.
OS. path. join (path1 [, path2 [,...]) # returns the result after combining multiple paths. The parameters before the first absolute path are ignored.
OS. path. getatime (path) # Return the last access time of the file or directory pointed to by path
OS. path. getmtime (path) # Return the last modification time of the file or directory pointed to by path
OS. name # string indicates the current platform. Win-> 'nt '; Linux-> 'posix'
OS. read (fd, n) # reads up to n Bytes from the file descriptor fd and returns a string containing the read bytes. The file descriptor fd corresponds to the end of the file and returns an empty string.
OS. readlink (path) # returns the file to which the soft link points
OS. remove (path) # delete a file with the path. If path is a folder, OSError will be thrown; check the following rmdir () to delete a directory.
OS. removedirs (path) # recursively delete directories. If the directory is empty, delete it and recursively go to the upper-level directory. If the directory is empty, delete it.
OS. rename (src, dst) # rename a file or directory from src to dst
OS. renames (old, new) # recursively rename the directory or rename the file.
OS. rmdir (path) # Delete the empty directory specified by path. If the directory is not empty, an OSError exception is thrown.
OS. sep # The path delimiter specified by the operating system. In Windows, it is \, and in Linux, It is "/"
OS. stat (path) # obtains the information of the path specified by path, which is equivalent to the stat () System Call in C API.
OS. stat_float_times ([newvalue]) # determines whether stat_result displays a timestamp as a float object.
OS. statvfs (path) # obtain the statistics of the file system in the specified path
OS. symlink (src, dst) # create a soft link
OS. system ("bash command") # Run the shell command to directly display
OS. tcgetpgrp (fd) # returns the process group associated with the terminal fd (an opened file descriptor returned by OS. open ().
OS. tcsetpgrp (fd, pg) # set the process group associated with the terminal fd (an opened file descriptor returned by OS. open () to pg.
OS. tempnam ([dir [, prefix]) # Return the unique path name used to create a temporary file.
OS. tmpfile () # returns a file object in the open mode (w + B). This file object has no folder entry and no file descriptor, and will be automatically deleted.
OS. tmpnam () # returns a unique path for creating a temporary file.
OS. ttyname (fd) # returns a string that represents the terminal device associated with the file descriptor fd. If fd is not associated with a terminal device, an exception is thrown.
OS. unlink (path) # delete the file path
OS. utime (path, times) # returns the access and modification time of the specified path file.
OS. walk (top [, topdown = True [, onerror = None [, followlinks = False]) # output the file name in the folder to move up or down in the middle of the tree.
OS. write (fd, str) # write a string to the file descriptor fd. Return the length of the actually written string.