#!/usr/bin/env python
# vim: set fileencoding=utf-8:
import os.path, fnmatch
import os, random, time

def listFiles(root, patterns='*', recurse=1, return_folders=0):

    # Expand patterns from semicolon-separated string to list           
    pattern_list = patterns.split(';')
    # Collect input and output arguments into one bunch
    class Bunch:
        def __init__(self, **kwds): self.__dict__.update(kwds)
    arg = Bunch(recurse=recurse, pattern_list=pattern_list,
        return_folders=return_folders, results=[])

    def visit(arg, dirname, files):
        # Append to arg.results all relevant files (and perhaps folders)
        for name in files:
            fullname = os.path.normpath(os.path.join(dirname, name))                #目录规范化
            if arg.return_folders or os.path.isfile(fullname):                      #判断是否返回目录。 是否是文件
                for pattern in arg.pattern_list:                                    #模式匹配用 "or" ,符合一个就ok
                    if fnmatch.fnmatch(name, pattern):
                        arg.results.append(fullname)                                #结果中添加文件名称
                        break
        # Block recursion if recursion was disallowed
        if not arg.recurse: files[:]=[]                               #把list中目录包含的文件/子目录置空，子目录没了哈

    os.path.walk(root, visit, arg)

    return arg.results

thefiles = listFiles('/home/gentoo/picture/wallpaper/', '*.jpg;*.gif;*.png', 1, 0)
while True:
    try:
        num = random.randint(0, len(thefiles))
        cmd = 'gconftool-2 --type string --set /desktop/gnome/background/picture_filename ' + thefiles[num-1]
        os.system(cmd)
        time.sleep(60*5);
    except:
        raise SystemExit