pxssh-使用某些长度的命令输出未正确返回

Question

When using pxssh from pexpect (Python 3-v4.6.0, Python 2-v4.2.1) to execute a command, the output of the command is not returned, only the command itself along with a control character (example below). This only occurs when using a command with a particular length, for example when setting the window size to 200, a command of length 189 character will trigger this behaviour, for a window size of 300, a 246 character command etc.

Example code with respective outputs:

Setup:

from pexpect import pxssh
conn = pxssh.pxssh()
conn.login(host, user, password)
conn.setwinsize(500, 200)
conn.setecho(False)
conn.sendline('')
conn.prompt(1)
conn.prompt(1)

Correct Expected Output:

conn.sendline('l'*188)
conn.prompt(1)
conn.before
b'llll**snip**lllll\x1b[Kl\r\n-sh: lllll*snip*lllll: command not found\r\n'

Incorrect Output:

conn.sendline('l'*189)
conn.prompt(1)
conn.before
b'lllll**snip**lllll\r\x1b[A'

Correct Expected Output:

conn.sendline('l'*190)
conn.prompt(1)
conn.before
b'lllll**snip**llllll\x1b[Kl\r\n-sh: lllll**snip**llllll: command not found\r\n'

Does anyone know what might be causing this?

Answer 1

In case anyone comes across this problem in the future. This issue occurs when a command of length = window size - length of prompt, which causes an additional prompt to incorrectly be inserted into the incoming data in turn causing the output to be incorrectly returned.

For more information see: https://github.com/pexpect/pexpect/issues/552