Develop Reference

How do you use pdflatex in Python?

I am trying to compile a .tex file in a Python script using pdflatex. The command pdflatex filename.tex works when I run it from the command line on Windows. However, attempting to run os.system("pdflatex filename.tex") just spits out 1 into the Python console and does not compile a pdf. I've also tried putting in the full file path similar to this person solved their problem but the same thing happens. Similarly, subprocess.call(['pdflatex', 'filename.tex']) just outputs a 1 and does not do anything.
It seems someone else has encountered the same problem in this thread, but on Mac instead of Windows. (But regardless of the operating system, they didn't find an answer.)
Why might this be happening?
EDIT: I've just discovered a solution. The script runs successfully (using the os.system approach) when I run the .py file using the command line. Previously I was attempting to run the script from RStudio, both using reticulate::source_python(filename) and also line-by-line via the reticulate REPL. Seems like the problem may actually be coming from R's reticulate package rather than anything to do with Python.
Fortunately RStudio has a terminal window so this doesn't end up being too inconvenient!

Python subprocess can't call "ssh"

I'm working on using the subprocess module to send shell commands from Python, specifically, ssh. Below is a barebones sample:
import subprocess
sp = subprocess.run(["ssh"], shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
print(f"stdout: {sp.stdout.decode()} \n\nstderr: {sp.stderr.decode()}")
This should return the ssh command help from stdout, and nothing from stderr. However, I get:
stdout:
stderr: 'ssh' is not recognized as an internal or external command,
operable program or batch file.
I've tried other commands, like echo and cd, and those work fine. I am also able to use ssh when manually typing the command into the shell, but it fails when I try to do it through subprocess. The directory C:\Windows\System32\OpenSSH does exist on my computer (and it contains ssh.exe), but for some strange reason I'm unable to cd to it using subprocess.
If it matters, subprocess is using the command prompt, cmd.exe, as it seems to be the default.
Any help is appreciated. Thanks!
-- Edits with tests from comments --
Using the absolute path C:/Windows/System32/OpenSSH/ssh.exe does not work, and gives The system cannot find the path specified via stderr. The OpenSSH folder doesn't seem to be visible to Python through subprocess
os.environ[PATH] contains both C:/Windows/System32/ and C:/Windows/System32/OpenSSH/
Running it with shell=False (either with the absolute path or just with ssh) raises an error in Python: FileNotFoundError: [WinError 2] The system cannot find the file specified

You say C:\Windows\System32\OpenSSH\ssh.exe exists, but that it's not found when running from Python. This is likely a result of having a 32 bit version of Python installed, rather than a 64 bit version.
If the path exists elsewhere, but not for Python, that would tend to implicate the file system redirector. Python is probably seeing C:\Windows\SysWOW64 when you tell it to look in C:\Windows\System32. I'd recommend uninstalling whatever Python you have, and explicitly installing a 64 bit version, so it isn't affected by the redirector, and sees the "real" System32.

subprocess.Popen not working in ubuntu (working fine in Windows)

I am right now in the same directory in which the file "lookup.csv" is residing.
I have tried following commands in Python 2.7:
import subprocess
subprocess.Popen("lookup.csv", shell = True)
The above is producing the following error:
lookup.csv : not found
I have double-checked for the working directory, tried lot of available troubleshooting options given in StakExchange, tried the same in Windows (and surprisingly it was working there), what more can I do?

There's no reason why this should work on Windows because lookup.csv clearly is a file which you want to open with open whereas subprocess.Popen creates a new process for working with the lookup.csv binary. Maybe Windows handles process failure differently.

Python os.chdir() not changing directory

So, I am following a simple tutorial "Python Tutorial: Automate Parsing and Renaming of Multiple Files" and am already encountering a problem where os.chdir() is not working. I am on a Windows 10 system, running python 3.6, and I have tried using both my regular terminal (which has cygwin installed) and bash on ubuntu on Windows.
Here is the code:
import os
print(os.getcwd())
os.chdir('c:/Users/Michelle Kaiser/Desktop/Lab_Progs/PI3Kalpha')
print(os.getcwd())
Here is the reg terminal:
C:\Users\Michelle Kaiser\Desktop\Lab_Progs>python rename.py
C:\Users\Michelle Kaiser\Desktop\Lab_Progs
C:\Users\Michelle Kaiser\Desktop\Lab_Progs>`
The path that it is returning corresponds to the folder my program is located in. I have moved the program 3 times to verify this. Also, it's obviously returning a path only once, so it's probably not responding to the 2 print statements.
Here is the bash terminal:
mkaiser#ZIPPY:/mnt/c/Users/Michelle Kaiser/Desktop/Lab_Progs$ python rename.py
/mnt/c/Users/Michelle Kaiser/Desktop/Lab_Progs
mkaiser#ZIPPY:/mnt/c/Users/Michelle Kaiser/Desktop/Lab_Progs$
I also tried running the code with os.path.exists(), which did not change the output on either terminal. I have definitely double checked that I am saving my program file from one test to the next. Thanks.

I've been trying to change a file that has no whitespace.
It seems like this person has a similar problem:
Python reading whitespace-separated file lines as separate lines

How to use websockify with python on windows or compiling websockify as windows executable (for more multiple client connection at a time)

I'm trying to get the websockify 0.6.0 running on windows but without any luck,
I have tried python websockify.py 1501 10.0.0.141:1501 but its not good, getting errors , like that:
Traceback (most recent call last):
File "websockify.py", line 1, in <module>
run
NameError: name 'run' is not defined
I also tried Compiling Websockify as Windows Executable , but this also didn't work
I use the following command run.exe 1501 10.0.0.141:1501 and it looks promising at the beginning, outputting the following to the console:
WARNING: no 'resource' module, daemonizing is disabled
WebSocket server settings:
- Listen on :1501
- Flash security policy server
- No SSL/TLS support (no cert file)
- proxying from :1501 to 10.0.0.141:1501
but then after trying to connect using the following from the browser ws://localhost:1501
**it outputs the following error
Traceback (most recent call last):
File "run", line 5, in <module>
File "websockify\websocketproxy.pyc", line 419, in websockify_init
File "websockify\websocket.pyc", line 1018, in start_server
UnboundLocalError: local variable 'exc' referenced before assignment
Any idea on how to use the websockify on windows / or how to use the compiled websockify as windows executable ?

The easiest way to get websockify working on Windows is to use the Node.js version of websockify (in the other/js directory). It works perfectly out of the box, with no shenanigans required.

To address this, use the modified following commands for your example source, start from the beginning of each step and see if it helps:
Firstly, install Portable Python 2.7
You then need to modify the setup.py (It looks like this is why you are getting your first error, as you may not have defined run):
from setuptools import setup, find_packages
# add (line 2):
import py2exe
setup(name=name,
# add (line 10):
console=['run'],
Ensure the above has executed correctly by inspecting setup.py and ensure it includes run.
In your local code, import the resources module to allow you to monitor, measure and control system resources utilized by your program
import resource
Inspect your local variable exc and ensure you have assigned a value to it before calling it (I'm guessing you may have attributed a system variable to it, but python was unable to do so as you did not have resources imported, and as such it was not assigned). If you like, put up an example of your code in the comment to this response and I'll take a closer look at this part.
Back to your source guide, navigate to the websockify folder in command prompt, then execute the following to compile websockify:
[Your path to Portable Python install]\App\python.exe setup.py py2exe --includes numpy
You will now see in the websockify directory a new dir 'dist' which contains the compiled exe. An example provided is:
run.exe 5901 localhost:5900
There is also a guide here to run websockify as a Windows Service if this suits (again mentioned in your source).
----Further edit for more detail----
Open up the two files that seem to be giving you issues (websockify\websocketproxy.pyc and websockify\websocket.pyc and ensure that any reference to a variable called "exc" is referenced after it has been assigned a value (small chance of an issue if you have not yet modified these files.
I believe that your code is relying upon making and monitoring changes to the system resources (such as ports etc) and you are not allowing your code to have these permissions, so it needs the resources module. If you are calling run.exe from a program (what I called your local code) then you need to import resources at the top. If you are just straight up calling the run.exe program from a command line, then try making this new program and see if this helps. If not, send me the contents of your websockify folder and run.exe and I will take a look
# Program Name: goAndRun.py
# Code:
import sys, string, os, arcgisscripting, resource
os.chdir( 'C:\\[Path_to_the_dir_containing_run.exe]' )
os.system( '"C:\\[Path_to_the_dir_containing_run.exe]\run.exe, 5901 localhost:5900"' )
And then use the command:
python goAndRun.py
Not being in your environment, I cannot tell if this will execute exactly as I have written it. The last line may also be:
os.system( '"C:\\[Path_to_the_dir_containing_run.exe]\run.exe"', '5901 localhost:5900' )