Python之File System

File System -- os, os.path, shutil

The *os* and *os.path* modules include many functions to interact with the file system. The *shutil* module can copy files.

• os module docs
• filenames = os.listdir(dir) -- list of filenames in that directory path (not including . and ..). The filenames are just the names in the directory, not their absolute paths.
• os.path.join(dir, filename) -- given a filename from the above list, use this to put the dir and filename together to make a path
• os.path.abspath(path) -- given a path, return an absolute form, e.g. /home/nick/foo/bar.html
• os.path.dirname(path), os.path.basename(path) -- given dir/foo/bar.html, return the dirname "dir/foo" and basename "bar.html"
• os.path.exists(path) -- true if it exists
• os.mkdir(dir_path) -- makes one dir, os.makedirs(dir_path) makes all the needed dirs in this path
• shutil.copy(source-path, dest-path) -- copy a file (dest path directories should exist)

## Example pulls filenames from a dir, prints their relative and absolute paths 
def printdir(dir):
   filenames = os.listdir(dir)
   for filename in filenames:
     print filename  ## foo.txt
     print os.path.join(dir, filename)  ## dir/foo.txt (relative to current dir)     
     print os.path.abspath(os.path.join(dir, filename)## /home/nick/dir/foo.txt