python之模块 os

# -*- coding: utf-8 -*-
#python 27
#xiaodeng
#python之模块 os



import os
'''
FUNCTIONS
    abort(...)#暂不了解
        abort() -> does not return!
        
        Abort the interpreter immediately.  This 'dumps core' or otherwise fails
        in the hardest way possible on the hosting operating system.
    
    access(...)#暂不了解
        access(path, mode) -> True if granted, False otherwise
        
        Use the real uid/gid to test for access to a path.  Note that most
        operations will use the effective uid/gid, therefore this routine can
        be used in a suid/sgid environment to test if the invoking user has the
        specified access to the path.  The mode argument can be F_OK to test
        existence, or the inclusive-OR of R_OK, W_OK, and X_OK.
    
    chdir(...)#改变当前工作目录,改变工作目录到dirname,相当于shell下cd
        chdir(path)
        
        Change the current working directory to the specified path.
    
    chmod(...)
        chmod(path, mode)
        
        Change the access permissions of a file.
    
    close(...)
        close(fd)
        
        Close a file descriptor (for low level IO).
    
    closerange(...)
        closerange(fd_low, fd_high)
        
        Closes all file descriptors in [fd_low, fd_high), ignoring errors.
    
    dup(...)
        dup(fd) -> fd2
        
        Return a duplicate of a file descriptor.
    
    dup2(...)
        dup2(old_fd, new_fd)
        
        Duplicate file descriptor.
    
    execl(file, *args)
        execl(file, *args)
        
        Execute the executable file with argument list args, replacing the
        current process.
    
    execle(file, *args)
        execle(file, *args, env)
        
        Execute the executable file with argument list args and
        environment env, replacing the current process.
    
    execlp(file, *args)
        execlp(file, *args)
        
        Execute the executable file (which is searched for along $PATH)
        with argument list args, replacing the current process.
    
    execlpe(file, *args)
        execlpe(file, *args, env)
        
        Execute the executable file (which is searched for along $PATH)
        with argument list args and environment env, replacing the current
        process.
    
    execv(...)
        execv(path, args)
        
        Execute an executable path with arguments, replacing current process.
        
            path: path of executable file
            args: tuple or list of strings
    
    execve(...)
        execve(path, args, env)
        
        Execute a path with arguments and environment, replacing current process.
        
            path: path of executable file
            args: tuple or list of arguments
            env: dictionary of strings mapping to strings
    
    execvp(file, args)
        execvp(file, args)
        
        Execute the executable file (which is searched for along $PATH)
        with argument list args, replacing the current process.
        args may be a list or tuple of strings.
    
    execvpe(file, args, env)
        execvpe(file, args, env)
        
        Execute the executable file (which is searched for along $PATH)
        with argument list args and environment env , replacing the
        current process.
        args may be a list or tuple of strings.
    
    fdopen(...)
        fdopen(fd [, mode='r' [, bufsize]]) -> file_object
        
        Return an open file object connected to a file descriptor.
    
    fstat(...)
        fstat(fd) -> stat result
        
        Like stat(), but for an open file descriptor.
    
    fsync(...)
        fsync(fildes)
        
        force write of file with filedescriptor to disk.
    
    getcwd(...)#获取当前目录
        getcwd() -> path
        
        Return a string representing the current working directory.
    
    getcwdu(...)
        getcwdu() -> path
        
        Return a unicode string representing the current working directory.
    
    getenv(key, default=None)
        Get an environment variable, return None if it doesn't exist.
        The optional second argument can specify an alternate default.
    
    getpid(...)
        getpid() -> pid
        
        Return the current process id
    
    isatty(...)
        isatty(fd) -> bool
        
        Return True if the file descriptor 'fd' is an open file descriptor
        connected to the slave end of a terminal.
    
    kill(...)
        kill(pid, sig)
        
        Kill a process with a signal.
    
    listdir(...)#获取目录内容，其结果为list类型
        listdir(path) -> list_of_strings
        
        Return a list containing the names of the entries in the directory.
        
            path: path of directory to list
        
        The list is in arbitrary order.  It does not include the special
        entries '.' and '..' even if they are present in the directory.
    
    lseek(...)
        lseek(fd, pos, how) -> newpos
        
        Set the current position of a file descriptor.
        Return the new cursor position in bytes, starting from the beginning.
    
    lstat(...)
        lstat(path) -> stat result
        
        Like stat(path), but do not follow symbolic links.
    
    makedirs(name, mode=511)#递归文件夹创建函数,
                            #os.makedirs('dirname1/dirname2') 可生成多层递归目录
        makedirs(path [, mode=0777])
        
        Super-mkdir; create a leaf directory and all intermediate ones.
        Works like mkdir, except that any intermediate path segment (not
        just the rightmost) will be created if it does not exist.  This is
        recursive.
    
    mkdir(...)#创建一个新的目录,目录已存在会报错，WindowsError: [Error 183] : '1'
        mkdir(path [, mode=0777])
        
        Create a directory.
    
    open(...)
        open(filename, flag [, mode=0777]) -> fd
        
        Open a file (for low level IO).
    
    pipe(...)
        pipe() -> (read_end, write_end)
        
        Create a pipe.
    
    popen(...)
        popen(command [, mode='r' [, bufsize]]) -> pipe
        
        Open a pipe to/from a command returning a file object.
    
    popen2(...)
    
    popen3(...)
    
    popen4(...)
    
    putenv(...)
        putenv(key, value)
        
        Change or add an environment variable.
    
    read(...)
        read(fd, buffersize) -> string
        
        Read a file descriptor.
    
    remove(...)#删除文件，参数可根绝对路径
        remove(path)
        
        Remove a file (same as unlink(path)).
    
    removedirs(name)#递归删除目录
        在os模块中使用removedirs方法时，要想把a目录和a目录下的b目录同时删除，代码os.removedirs(r'D:a')，只有符合以下条件时，a和b两个目录才会被同时删除。
            1）a目录下只有b目录
            2）b目录中必须是一个空目录
            两者缺一不可
        removedirs(path)
        
        Super-rmdir; remove a leaf directory and all empty intermediate
        ones.  Works like rmdir except that, if the leaf directory is
        successfully removed, directories corresponding to rightmost path
        segments will be pruned away until either the whole path is
        consumed or an error occurs.  Errors during this latter phase are
        ignored -- they generally mean that a directory was not empty.
    
    rename(...)#文件重命名
        rename(old, new)
        
        Rename a file or directory.
    
    renames(old, new)#递归重命名文件夹或者文件,暂不知道怎么使用
        renames(old, new)
        
        Super-rename; create directories as necessary and delete any left
        empty.  Works like rename, except creation of any intermediate
        directories needed to make the new pathname good is attempted
        first.  After the rename, directories corresponding to rightmost
        path segments of the old name will be pruned until either the
        whole path is consumed or a nonempty directory is found.
        
        Note: this function can fail with the new directory structure made
        if you lack permissions needed to unlink the leaf directory or
        file.
    
    rmdir(...)#删除空目录，如果目录非空报错，WindowsError: [Error 145] : '1'
        rmdir(path)
        
        Remove a directory.
    
    spawnl(mode, file, *args)
        spawnl(mode, file, *args) -> integer
        
        Execute file with arguments from args in a subprocess.
        If mode == P_NOWAIT return the pid of the process.
        If mode == P_WAIT return the process's exit code if it exits normally;
        otherwise return -SIG, where SIG is the signal that killed it.
    
    spawnle(mode, file, *args)
        spawnle(mode, file, *args, env) -> integer
        
        Execute file with arguments from args in a subprocess with the
        supplied environment.
        If mode == P_NOWAIT return the pid of the process.
        If mode == P_WAIT return the process's exit code if it exits normally;
        otherwise return -SIG, where SIG is the signal that killed it.
    
    spawnv(...)
        spawnv(mode, path, args)
        
        Execute the program 'path' in a new process.
        
            mode: mode of process creation
            path: path of executable file
            args: tuple or list of strings
    
    spawnve(...)
        spawnve(mode, path, args, env)
        
        Execute the program 'path' in a new process.
        
            mode: mode of process creation
            path: path of executable file
            args: tuple or list of arguments
            env: dictionary of strings mapping to strings
    
    startfile(...)
        startfile(filepath [, operation]) - Start a file with its associated
        application.
        
        When "operation" is not specified or "open", this acts like
        double-clicking the file in Explorer, or giving the file name as an
        argument to the DOS "start" command: the file is opened with whatever
        application (if any) its extension is associated.
        When another "operation" is given, it specifies what should be done with
        the file.  A typical operation is "print".
        
        startfile returns as soon as the associated application is launched.
        There is no option to wait for the application to close, and no way
        to retrieve the application's exit status.
        
        The filepath is relative to the current directory.  If you want to use
        an absolute path, make sure the first character is not a slash ("/");
        the underlying Win32 ShellExecute function doesn't work if it is.
    
    stat(...)
             #os.stat('path/filename') 获取文件/目录信息
        stat(path) -> stat result
        
        Perform a stat system call on the given path.
    
    stat_float_times(...)
        stat_float_times([newval]) -> oldval
        
        Determine whether os.[lf]stat represents time stamps as float objects.
        If newval is True, future calls to stat() return floats, if it is False,
        future calls return ints. 
        If newval is omitted, return the current setting.
    
    strerror(...)
        strerror(code) -> string
        
        Translate an error code to a message string.
    
    system(...)#运行shell命令
        #os.system('cmd') #启动dos
        #启动cmd命令符
        Execute the command (a string) in a subshell.
    
    tempnam(...)
        tempnam([dir[, prefix]]) -> string
        
        Return a unique name for a temporary file.
        The directory and a prefix may be specified as strings; they may be omitted
        or None if not needed.
    
    times(...)
        times() -> (utime, stime, cutime, cstime, elapsed_time)
        
        Return a tuple of floating point numbers indicating process times.
    
    tmpfile(...)
        tmpfile() -> file object
        
        Create a temporary file with no directory entries.
    
    tmpnam(...)
        tmpnam() -> string
        
        Return a unique name for a temporary file.
    
    umask(...)
        umask(new_mask) -> old_mask
        
        Set the current numeric umask and return the previous umask.
    
    unlink(...)
        unlink(path)
        
        Remove a file (same as remove(path)).
    
    urandom(...)
        urandom(n) -> str
        
        Return n random bytes suitable for cryptographic use.
    
    utime(...)
        utime(path, (atime, mtime))
        utime(path, None)
        
        Set the access and modified time of the file to the given values.  If the
        second form is used, set the access and modified times to the current time.
    
    waitpid(...)
        waitpid(pid, options) -> (pid, status << 8)
        
        Wait for completion of a given process.  options is ignored on Windows.
    
    walk(top, topdown=True, onerror=None, followlinks=False)#目录遍历
        Directory tree generator.
        
        For each directory in the directory tree rooted at top (including top
        itself, but excluding '.' and '..'), yields a 3-tuple
        WindowsError: [Error 183] : '1'
            dirpath, dirnames, filenames
        
        
        Example:
        
        import os
        from os.path import join, getsize
        for root, dirs, files in os.walk('python/Lib/email'):
            print root, "consumes",
            print sum([getsize(join(root, name)) for name in files]),
            print "bytes in", len(files), "non-directory files"
            if 'CVS' in dirs:
                dirs.remove('CVS')  # don't visit CVS directories
    
    write(...)
        write(fd, string) -> byteswritten
        
        Write a string to a file descriptor.


DATA:
    os.name#输出字符串指示正在使用的平台。如果是window 则用'nt'表示，对于Linux/Unix用户，它是'posix
    os.linesep字符串给出当前平台使用的行终止符 '
'            #Windows使用'
'，Linux使用'
'而Mac使用'
'。
    os.curdir 返回当前目录: ('.')
    os.pardir 获取当前目录的父目录字符串名：('..')
    os.environ 获取系统环境变量
    
>>> 
'''