使用sys.stdout将输出从pexpect保存到文本文件

Question

I am using pexpect to run external application on some input files and I want to save the output to a logfile. I generally manage to do this, but this application run iterative calculations and when it makes more than approx. 20 cycles my output is cut.

I am sure that my calculations are running past this point up to the end.

My code:

sys.stdout = open(logfile_path , 'a') child = pexpect.run('app input_files' , logfile=sys.stdout , cwd=path_cwd)

Is there any more proper way to do this, so I could save all the output?

Answer 1

Perhaps a timeout happens. Check exit status, it should be non-zero in this case. Pass timeout=None to disable the timeout, pass withexitstatus=True to get the exit status:

#!/usr/bin/env python
import subprocess
import sys
import pexpect  # $ pip install pexpect

N = 10**7
command = [sys.executable, '-c', r"print('\n'*%d)" % N]
subprocess_output = subprocess.check_output(command, universal_newlines=True)
assert len(subprocess_output) == (N + 1), repr(subprocess_output[:30])
output, status = pexpect.runu(command[0], args=command[1:], withexitstatus=1,
                              timeout=None)
assert not status, (status, repr(output.strip()))
print(repr(output[:30]))
assert subprocess_output.splitlines() == output.splitlines()
assert len(output) == 2*(N + 1) # \n -> \r\n