pexpect.exceptions.TIMEOUT: Timeout exceeded.
在一个Python项目中，要执行“/usr/bin/sftp [email protected]”命令连接远程FTP服务器，代码如下：
_pass = 'assword:'
_prompt = 'sftp> '
_newKey = "Are you sure you want to continue connecting (yes/no)?"
self._client = pexpect.spawn(command_connect_sftp)
match = [self._pass, self._newKey]
i = self._client.expect(match)
if i == 1:
self._client.sendline("yes")
self._client.expect(match)
self._client.sendline(password)
self._client.expect(self._prompt)
可以看到，在发生连接FTP服务器的命令后，通过expect()检查可能的结果。但是在执行过程中得到如下异常：
ERROR Internal system error occured handling command install for lidus2376
help Internal system error!
Traceback (most recent call last):
File "/usr/local/lib/python3.5/dist-packages/pexpect/expect.py", line 99, in expect_loop incoming = spawn.read_nonblocking(spawn.maxread, timeout)
File "/usr/local/lib/python3.5/dist-packages/pexpect/pty_spawn.py", line 462, in read_nonblocking raise TIMEOUT('Timeout exceeded.')
pexpect.exceptions.TIMEOUT: Timeout exceeded.
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/userbbauto/bbauto/src/bbautoserver.py", line 335, in _handle_api_install_request tgf_install = TgfInstall(self.input_params)
File "/home/userbbauto/bbauto/src/tgfinstall.py", line 52, in __init__ debug=self.active_debug_groups, password=self.BBAUTO_PASSWORD)
File "/home/userbbauto/bbauto/src/sftpconnection3.py", line 47, in __init__ i = self._client.expect(match)
File "/usr/local/lib/python3.5/dist-packages/pexpect/spawnbase.py", line 321, in expect timeout, searchwindowsize, async)
File "/usr/local/lib/python3.5/dist-packages/pexpect/spawnbase.py", line 345, in expect_list return exp.expect_loop(timeout)
File "/usr/local/lib/python3.5/dist-packages/pexpect/expect.py", line 107, in expect_loop return self.timeout(e)
File "/usr/local/lib/python3.5/dist-packages/pexpect/expect.py", line 70, in timeout raise TIMEOUT(msg)
pexpect.exceptions.TIMEOUT: Timeout exceeded.
command: /usr/bin/sftp
args: ['/usr/bin/sftp', '[email protected]']
buffer (last 100 chars): b' NOT AN AUTHORIZED USER, PLEASE EXIT IMMEDIATELY\r\nConnected to ftp.ericsson.se.\r\nsftp> '
before (last 100 chars): b' NOT AN AUTHORIZED USER, PLEASE EXIT IMMEDIATELY\r\nConnected to ftp.ericsson.se.\r\nsftp> '
after:
match: None
match_index: None
exitstatus: None
flag_eof: False
pid: 73
child_fd: 9
closed: False
timeout: 30
delimiter:
logfile: None
logfile_read: None
logfile_send: None
maxread: 2000
ignorecase: False
searchwindowsize: None
delaybeforesend: 0.05
delayafterclose: 0.1
delayafterterminate: 0.1
searcher:
searcher_re:
0: re.compile("b'assword:'")
1: re.compile("b'Are you sure you want to continue connecting (yes/no)?'")
分析发现异常的原因是expect()语句超时，期望得到的结果没有得到，直到超时抛出异常。
这是因为期望得到的结果只包含两种情况，一种是提示将FTP服务器加入到known_hosts中，另一种是提示输入密码。但是，由于当前机器上不检查hosts的公钥（避免了第一种提示），使用提前生成的私钥（避免了第二章提示），因而还有第三种可能，就是使用用户名和私钥直接连接FTP成功，从而得到了“ftp> ”的结果。
修改代码如下，解决该异常：
...
match = [self._pass, self._newKey, self._promt]
i = self._client.expect(match)
if i==2:
return
if i==1:
...