官方文档看这里 https://docs.python.org/3.5/library/os.html
http://www.cnblogs.com/wupeiqi/articles/5501365.html
os.path.exists(file) 如果file存在于当前目录下,返回True,否则返回False
os.path.abspath(file) 返回file的绝对路径
os.path.dirname(file) 返回file的上级目录名
sys.path.append(path) 添加path到环境变量
os.system(command)
def system(*args, **kwargs): # real signature unknown """ Execute the command in a subshell. """ pass
Execute the command (a string) in a subshell. 系统命令如果本身就会打印结果,那么你会在屏幕上看到结果。返回值是进程的退出状态,若成功执行,则返回值为0,若有报错,返回值为错误代码。
os.popen(command[, mode[, bufsize]])
# Supply os.popen() def popen(cmd, mode="r", buffering=-1): if not isinstance(cmd, str): raise TypeError("invalid cmd type (%s, expected string)" % type(cmd)) if mode not in ("r", "w"): raise ValueError("invalid mode %r" % mode) if buffering == 0 or buffering is None: raise ValueError("popen() does not support unbuffered streams") import subprocess, io if mode == "r": proc = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, bufsize=buffering) return _wrap_close(io.TextIOWrapper(proc.stdout), proc) else: proc = subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE, bufsize=buffering) return _wrap_close(io.TextIOWrapper(proc.stdin), proc)
执行系统命令,执行结果写到一个临时文件里面,返回值是这个打开的文件对象。mode默认值为r,即默认以只读方式打开文件;buffersize默认是系统缓冲区大小(buffer缓冲,此概念适用于磁盘写数据;cache缓存,此概念适用于磁盘读数据)。
既然返回的是一个文件对象,那么接下来可以理解os.popen().read(),是把这个文件对象中的内容读出来,返回值就是文件中的内容。
os.path.exists('文件名')
判断文件是否存在,存在返回True,不存在返回False
def mkdir(*args, **kwargs): # real signature unknown
"""
Create a directory.
If dir_fd is not None, it should be a file descriptor open to a directory,
and path should be relative; path will then be relative to that directory.
dir_fd may not be implemented on your platform.
If it is unavailable, using it will raise a NotImplementedError.
The mode argument is ignored on Windows.
"""
pass