Python and FTP

1 FTP (File Transfer Protocol) workflow

1 clients connect to an FTP server on a remote host

2 Client input user name and password (or ' anomymous ' and e-mail address)

3 Client for various file transfer and information query operations

4 client exits directly from remote FTP server, ends transmission

FTP two modes: active and passive, only the active mode server uses the data port, number 20th. In passive mode, the server is just a high number of client-side random port numbers, and the client must actively establish the connection, number 21st.

2 python and FTP

Import the Ftplib module and instantiate a ftplib. FTP class object, all FTP operations (such as login, transfer files and logoff) are to be completed by this object

Ftplib. FTP class method, only introduce a few common

Login (user= ' anonymous ', passwd= ", act=") #登录服务器, all parameters are optional

PWD #获取当前目录

CWD (path) #把当前工作目录设置path所示的路径 (e.g. path=/ftp/byq/example)

Dir ([path[,... [, CB]]) # Displays the contents of the path directory, optional parameter CB is a callback function, passed to the Retrlines () method

Retrbinary (cmd,cb[,8kb])

# download file, just process binary file, callback function CB used to process each piece (default size 8kb) of downloaded data

Storbinary (cmd,f[,8kb]) #处理二进制文件, to be given an object F, upload block BS size default 8kb

3 Client FTP instance

1 ImportFtplib2 ImportSocket3 ImportOS4 5 6Host ='Ftp,website'7Dirn ='Filedir'8Files ='filename'9 Ten  One defMain (): A     Try: -f =Ftplib. FTP (host) -     except(Socket.error, Socket.gaierror) as E: the         Print('error:cannot Reach "%s"'%host) -         return -     Print('***connected to Hos "%s"'%host) -      +     Try: - F.login () +     exceptFtplib.error_perm: A         Print('Error:cannot Login anonymously') at f.quit () -         return  -     Print('***logged in as "anonymous"') -      -     Try: - f.cwd (Dirn) in     exceptFtplib.error_perm: -         Print('error:cannot CD to "%s"'%Dirn) to f.quit () +         return  -     Print('***changed to "%s" folder'%Dirn) the      *     Try: $F.retrbinary ('retr%s'% files, open (Files,'WB'). Write)Panax Notoginseng     exceptFtplib.error_perm: -         Print('error:cannot Read Files "%s"'%files) the os.unlink (Files) +     Else: A         Print('***downloaded "%s" to cmd'%files) the f.quit () +      -     if __name__=='__main__':#the usual way to run stand-alone scripts $ Main ()     

Python and FTP