Problem
The code below is a simulation of a real terminal, in this case, a CMD terminal. The problem is that the "cls" don't clear the STDOUT of CMD. So, the string STDOUT start to stay so much extensive.
Example of problem
Microsoft Windows [versÆo 10.0.19042.746]
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C:\Users\Lsy\PycharmProjects\Others>chdir
C:\Users\Lsy\PycharmProjects\Others
C:\Users\Lsy\PycharmProjects\Others>echo test
test
C:\Users\Lsy\PycharmProjects\Others>cls
Type:
Question
How to clear the STDOUT?
Script
import subprocess
f = open('output.txt', 'w')
proc = subprocess.Popen('cmd.exe', stderr=subprocess.STDOUT, stdin=subprocess.PIPE, stdout=f, shell=True)
while True:
command = input('Type:')
command = command.encode('utf-8') + b'\n'
proc.stdin.write(command)
proc.stdin.flush()
with open('output.txt', 'r') as ff:
print(ff.read())
ff.close()
This is not how I recommend using sub processes - but I'm assuming you have some reason for doing things this way...
Given:
You've directed the CMD sub process to STDOUT to a file called "output.txt".
The CLS character is captured in the output.txt.
Your terminal then displaying the contents of the "output.txt" file (which is not ever cleared) and leaves a mess.
Therefore: If you want to "clear" your sub process terminal, then you will have to flush your "output.txt" file.
You can trivially do this by processing on the "command" variable before encoding and sending it to the sub process.
e.g:
import subprocess
import os
f = open('output.txt', 'w')
proc = subprocess.Popen('cmd.exe', stderr=subprocess.STDOUT, stdin=subprocess.PIPE, stdout=f, shell=True)
while True:
command = input('Type:')
if command == "cls":
open('output.txt', 'w').close()
os.system('cls' if os.name == 'nt' else 'clear')
else:
command = command.encode('utf-8') + b'\n'
proc.stdin.write(command)
proc.stdin.flush()
with open('output.txt', 'r+') as ff:
print(ff.read())
You could maybe also not redirect the output to a text file...
Related
I'm trying to read the content of a file with python 3.8.5 but the output is empty, I don't understand what I'm doing wrong.
Here is the code:
import subprocess
import os
filename = "ls.out"
ls_command = "ls -la"
file = open(filename, "w")
subprocess.Popen(ls_command, stdout=file, shell=True)
file.close()
# So far, all is ok. The file "ls.out" is correctly created and filled with the output of "ls -la" command"
file = open(filename, "r")
for line in file:
print(line)
file.close()
The output of this script is empty, it doesn't print anything. I'm not able to see the content of ls.out.
What is not correct here ?
Popen creates a new process and launches it but returns immediately. So the end result is that you've forked your code and have both processes running at once. Your python code in executing faster than the start and finish of ls. Thus, you need to wait for the process to finish by adding a call to wait():
import subprocess
import os
filename = "ls.out"
ls_command = "ls -la"
file = open(filename, "w")
proc = subprocess.Popen(ls_command, stdout=file, shell=True)
proc.wait()
file.close()
file = open(filename, "r")
for line in file:
print(line)
file.close()
Popen merely starts the subprocess. Chances are the file is not yet populated when you open it.
If you want to wait for the Popen object to finish, you have to call its wait method, etc; but a much better and simpler solution is to use subprocess.check_call() or one of the other higher-level wrappers.
If the command prints to standard output, why don't you read it drectly?
import subprocess
import shlex
result = subprocess.run(
shlex.split(ls_command), # avoid shell=True
check=True, text=True, capture_output=True)
line = result.stdout
I am trying to run a command and redirect the output to a .txt file as well as be able to see it in terminal using subprocess.run(). I previously used 2>&1 | file.txt to accomplish this but would like to mimic that flavor with subprocess.run() and shell = False
I am currently able to redirect stdout to a .txt. successfully but I would like to be able to see it in terminal as well. Is there a way to accomplish this? I am on Python 3.6
with open(model_dest_dir + 'Deepspeech_progress.txt', 'w') as f:
train_model = subprocess.run(train_cmds, shell = False, cwd = '/home/', env = export_dict, stdout = f)
#for stdout_line in iter(train_model.stdout.readline, b''):
# print(stdout_line)
f.close()
Looks like I have a working solution albeit not with subprocess.run(). I had to use Popen like so:
# train the model and write logs to .txt file
with open(model_dest_dir + 'Deepspeech_progress.txt', 'w') as f:
train_model_proc = subprocess.Popen(train_cmds, cwd = '//DeepSpeech/', env = export_dict, stdout = subprocess.PIPE, stderr = subprocess.STDOUT, universal_newlines = True)
for line in train_model_proc.stdout:
sys.stdout.write(line)
f.write(line)
train_model_proc.wait() # wait for Popen to finish
f.close()
I'm creating a text file, and immediately after calling a subprocess that does some computation based on the text file.
When I call the subprocess by itself, it's able to read from the file as expected, but when I try to create a file and write to it immediately before, it is not able to read from the file.
f = open('name_data.txt', 'w')
f.write(name)
f.close()
cmd = ['g2p-seq2seq', '--decode', 'name_data.txt', '--model', 'g2p-seq2seq-cmudict']
process = subprocess.Popen(cmd, stdout=subprocess.PIPE)
process.wait()
#etc....
import subprocess
open("Edited.py", "w").write("Thing To Write")
A = subprocess.Popen('Command you want to call', shell = True, stdout = subprocess.PIPE, stderr = subprocess.PIPE)
print(A.communicate())
Is there any possible way to communicate with the cmd and at the same time save all its output to a file?
I mean that after every command the output will be saved, not at the end of the sub-process.
I want it to be something like this:
import subprocess
process = subprocess.Popen('C:\\Windows\\system32\\cmd.exe', stdout=subprocess.PIPE,
stdin=subprocess.PIPE)
while True:
with open("log.txt", "a+") as myfile:
myfile.write(process.stdout.readlines())
process.stdin(raw_input())
You have two ways of doing this, either by creating an iterator from the read or readline functions and do:
import subprocess
import sys
with open('test.log', 'w') as f:
process = subprocess.Popen(your_command, stdout=subprocess.PIPE)
for c in iter(lambda: process.stdout.read(1), ''):
sys.stdout.write(c)
f.write(c)
or
import subprocess
import sys
with open('test.log', 'w') as f:
process = subprocess.Popen(your_command, stdout=subprocess.PIPE)
for line in iter(process.stdout.readline, ''):
sys.stdout.write(line)
f.write(line)
I use external library, like this:
from some_lib import runThatProgram
infile = '/tmp/test'
outfile = '/tmp/testout'
runThatProgram(infile, outfile)
while runThatProgram is:
def runThatProgram(infile, outfile):
os.system("%s %s > %s" % ('thatProgram', infile, outfile))
The problem is that 'thatProgram' returns lots of stuff on STDERR, I want to redirect it to a file, but I cannot edit runThatProgram code because it is in third party lib!
To illustrate what Rosh Oxymoron said, you can hack the code like this :
from some_lib import runThatProgram
infile = '/tmp/test'
outfile = '/tmp/testout 2>&1'
runThatProgram(infile, outfile)
with this, it will call
thatProgram /tmp/test > /tmp/testout 2>&1
that will redirected stderr (2) to stdout (1), and everything will be logged in your outfile.
To elaborate on using subprocess, you can open it, give it a pipe and then work from there so
import subprocess
program = "runthatprogram.py".split()
process = subprocess.Popen(program, stdout = subprocess.PIPE, stderr = open('stderr','w')) #stderr to fileobj
process.communicate()[0] #display stdout