python3os

1. 如何學習python的os模塊

一、os模塊概述

Python os模塊包含普遍的操作系統功能。如果你希望你的程序能夠與平台無關的話，這個模塊是尤為重要的。(一語中的)

二、常用方法

1、os.name

輸出字元串指示正在使用的平台。如果是window 則用'nt'表示，對於linux/Unix用戶，它是'posix'。

2、os.getcwd()

函數得到當前工作目錄，即當前Python腳本工作的目錄路徑。

3、os.listdir()

返回指定目錄下的所有文件和目錄名。

>>> os.listdir(os.getcwd())
['Django', 'DLLs', 'Doc', 'include', 'Lib', 'libs', 'LICENSE.txt', 'MySQL-python-wininst.log', 'NEWS.txt', 'PIL-wininst.log', 'python.exe', 'pythonw.exe', 'README.txt', 'RemoveMySQL-python.exe', 'RemovePIL.exe', 'Removesetuptools.exe', 'Scripts', 'setuptools-wininst.log', 'tcl', 'Tools', 'w9xpopen.exe']
>>>

4、os.remove()

刪除一個文件。

5、os.system()

運行shell命令。

>>> os.system('dir')
0
>>> os.system('cmd') #啟動dos

6、os.sep 可以取代操作系統特定的路徑分割符。

7、os.linesep字元串給出當前平台使用的行終止符

>>> os.linesep
'\r\n' #Windows使用'\r\n'，Linux使用'\n'而Mac使用'\r'。
>>> os.sep
'\\' #Windows
>>>

8、os.path.split()

函數返回一個路徑的目錄名和文件名

>>> os.path.split('C:\\Python25\\abc.txt')
('C:\\Python25', 'abc.txt')

9、os.path.isfile()和os.path.isdir()函數分別檢驗給出的路徑是一個文件還是目錄。

>>> os.path.isdir(os.getcwd())
True
>>> os.path.isfile('a.txt')
False

10、os.path.exists()函數用來檢驗給出的路徑是否真地存在

>>> os.path.exists('C:\\Python25\\abc.txt')
False
>>> os.path.exists('C:\\Python25')
True
>>>

11、os.path.abspath(name):獲得絕對路徑

12、os.path.normpath(path):規范path字元串形式

13、os.path.getsize(name):獲得文件大小，如果name是目錄返回0L

14、os.path.splitext():分離文件名與擴展名

>>> os.path.splitext('a.txt')
('a', '.txt')

15、os.path.join(path,name):連接目錄與文件名或目錄

>>> os.path.join('c:\\Python','a.txt')
'c:\\Python\\a.txt'
>>> os.path.join('c:\\Python','f1')
'c:\\Python\\f1'
>>>

16、os.path.basename(path):返迴文件名

>>> os.path.basename('a.txt')
'a.txt'
>>> os.path.basename('c:\\Python\\a.txt')
'a.txt'
>>>

17、os.path.dirname(path):返迴文件路徑

>>> os.path.dirname('c:\\Python\\a.txt')
'c:\\Python'

2. windows python3 怎樣獲得os的返回值

解決：查閱了文檔發現os.system()的返回為：
On Unix, the return value is the exit status of the process encoded in the format specified for wait().
而os.wait()的返回為：
a 16-bit number, whose low byte is the signal number that killed the process, and whose high byte is the exit status (if the signal number
is zero);
os.system的返回值並不是執行程序的返回結果。而是一個16位的數，它的高位才是返回碼。也就是說os.system()返回256即 0×0100，返回碼應該是其高位0×01即1。所以要獲取程序運行退出的值（比如C的main函數中的return 0），需要處理一下。
ret = os.system('./a.out')
ret >>= 8
這樣才能獲取到正確的返回值。另外還要注意：python獲取到的值是無符號整數，所以返回負值的時候，列印出來是很大的正值。比如返回-1，python 會獲取到255，-2則254，以此類推。所以最好就判斷是否為0就可以了，實在要判斷自己寫的c程序返回值，建議返回0,1,2,3等值，出錯返回 -1。
另外，我遇到一次明明處理好了返回值，c程序調試信息提示也該返回值0了，結果python獲取到的是 -1，而且無論c程序返回多少，python都獲取-1。後來排查c程序的問題，發現原來是因為我這個python程序本身是由另一個C程序調用的，而調 用它的那個C程序中將SIGCLD信號忽略了（這表明python是根據子進程退出時產生的信號來獲取返回值的），我將那個C程序的SIGCLD綁定到函 數，即使那個函數什麼也不做，python也能獲取到正確的返回值了。
/**********************************************************************************************************************/
linux命令執行後無論成功與否都有一個返回值：
如果為 0，則表示命令執行成功，其它值則表示錯誤，具體的錯誤碼含義如下：
"OS error code 1: Operation not permitted"
"OS error code 2: No such file or directory"
"OS error code 3: No such process"
"OS error code 4: Interrupted system call"
"OS error code 5: Input/output error"
"OS error code 6: No such device or address"
"OS error code 7: Argument list too long"
"OS error code 8: Exec format error"
"OS error code 9: Bad file descriptor"
"OS error code 10: No child processes"
"OS error code 11: Resource temporarily unavailable"
"OS error code 12: Cannot allocate memory"
"OS error code 13: Permission denied"
"OS error code 14: Bad address"
"OS error code 15: Block device required"
"OS error code 16: Device or resource busy"
"OS error code 17: File exists"
"OS error code 18: Invalid cross-device link"
"OS error code 19: No such device"
"OS error code 20: Not a directory"
"OS error code 21: Is a directory"
"OS error code 22: Invalid argument"
"OS error code 23: Too many open files in system"
"OS error code 24: Too many open files"
"OS error code 25: Inappropriate ioctl for device"
"OS error code 26: Text file busy"
"OS error code 27: File too large"
"OS error code 28: No space left on device"
"OS error code 29: Illegal seek"
"OS error code 30: Read-only file system"
"OS error code 31: Too many links"
"OS error code 32: Broken pipe"
"OS error code 33: Numerical argument out of domain"
"OS error code 34: Numerical result out of range"
"OS error code 35: Resource deadlock avoided"
"OS error code 36: File name too long"
"OS error code 37: No locks available"
"OS error code 38: Function not implemented"
"OS error code 39: Directory not empty"
"OS error code 40: Too many levels of symbolic links"
"OS error code 42: No message of desired type"
"OS error code 43: Identifier removed"
"OS error code 44: Channel number out of range"
"OS error code 45: Level 2 not synchronized"
"OS error code 46: Level 3 halted"
"OS error code 47: Level 3 reset"
"OS error code 48: Link number out of range"
"OS error code 49: Protocol driver not attached"
"OS error code 50: No CSI structure available"
"OS error code 51: Level 2 halted"
"OS error code 52: Invalid exchange"
"OS error code 53: Invalid request descriptor"
"OS error code 54: Exchange full"
"OS error code 55: No anode"
"OS error code 56: Invalid request code"
"OS error code 57: Invalid slot"
"OS error code 59: Bad font file format"
"OS error code 60: Device not a stream"
"OS error code 61: No data available"
"OS error code 62: Timer expired"
"OS error code 63: Out of streams resources"
"OS error code 64: Machine is not on the network"
"OS error code 65: Package not installed"
"OS error code 66: Object is remote"
"OS error code 67: Link has been severed"
"OS error code 68: Advertise error"
"OS error code 69: Srmount error"
"OS error code 70: Communication error on send"
"OS error code 71: Protocol error"
"OS error code 72: Multihop attempted"
"OS error code 73: RFS specific error"
"OS error code 74: Bad message"
"OS error code 75: Value too large for defined data type"
"OS error code 76: Name not unique on network"
"OS error code 77: File descriptor in bad state"
"OS error code 78: Remote address changed"
"OS error code 79: Can not access a needed shared library"
"OS error code 80: Accessing a corrupted shared library"
"OS error code 81: .lib section in a.out corrupted"
"OS error code 82: Attempting to link in too many shared libraries"
"OS error code 83: Cannot exec a shared library directly"
"OS error code 84: Invalid or incomplete multibyte or wide character"
"OS error code 85: Interrupted system call should be restarted"
"OS error code 86: Streams pipe error"
"OS error code 87: Too many users"
"OS error code 88: Socket operation on non-socket"
"OS error code 89: Destination address required"
"OS error code 90: Message too long"
"OS error code 91: Protocol wrong type for socket"
"OS error code 92: Protocol not available"
"OS error code 93: Protocol not supported"
"OS error code 94: Socket type not supported"
"OS error code 95: Operation not supported"
"OS error code 96: Protocol family not supported"
"OS error code 97: Address family not supported by protocol"
"OS error code 98: Address already in use"
"OS error code 99: Cannot assign requested address"
"OS error code 100: Network is down"
"OS error code 101: Network is unreachable"
"OS error code 102: Network dropped connection on reset"
"OS error code 103: Software caused connection abort"
"OS error code 104: Connection reset by peer"
"OS error code 105: No buffer space available"
"OS error code 106: Transport endpoint is already connected"
"OS error code 107: Transport endpoint is not connected"
"OS error code 108: Cannot send after transport endpoint shutdown"
"OS error code 109: Too many references: cannot splice"
"OS error code 110: Connection timed out"
"OS error code 111: Connection refused"
"OS error code 112: Host is down"
"OS error code 113: No route to host"
"OS error code 114: Operation already in progress"
"OS error code 115: Operation now in progress"
"OS error code 116: Stale NFS file handle"
"OS error code 117: Structure needs cleaning"
"OS error code 118: Not a XENIX named type file"
"OS error code 119: No XENIX semaphores available"
"OS error code 120: Is a named type file"
"OS error code 121: Remote I/O error"
"OS error code 122: Disk quota exceeded"
"OS error code 123: No medium found"
"OS error code 124: Wrong medium type"
"OS error code 125: Operation canceled"
"OS error code 126: Required key not available"
"OS error code 127: Key has expired"
"OS error code 128: Key has been revoked"
"OS error code 129: Key was rejected by service"
"OS error code 130: Owner died"
"OS error code 131: State not recoverable"