Develop Reference

input commands after opening a shortcut?

I am using Python 3.10.6 and Miniconda 3
What I'm trying to do is write a python script which will open a .cmd file. simple enough, but the problem is it has to be opened in anaconda. I've been able to have my script open the .cmd through the standard command line, and I've been able to have the script open anaconda. But I'm unable to do both in sequence, open the anaconda terminal and then pass a command to it, instructing it to open the .cmd
opening anaconda:
path = 'C:\\Users\...\shortcuts\\conda.lnk'
cmds = 'C:\\Users\\...test.cmd'
cmd_result = subprocess.run(path, shell=True, check=True,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
universal_newlines=True,
text=True )
print(cmd_result.args)
print(cmd_result.stdout)
this works properly when i open either anaconda path or test.cmd directly using the subprocess.run function. but when I attempt to open test.cmd as a command argument in the anaconda terminal, it doesn't work
path = 'C:\\Users\...\shortcuts\\conda.lnk'
cmds = [path,'/C','C:\\Users\\...test.cmd']
cmd_result = subprocess.run(cmds, shell=True, check=True,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
universal_newlines=True,
text=True )
I believe this is the relevant part of the error code it returns
File "C:\Users\...dream_restart_module.py", line 17, in dream_restart
cmd_result = subprocess.run(cmds, shell=True, check=True,
File "C:\Users\...Python310\lib\subprocess.py", line 524, in run
raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['C:\\Users\\...shortcuts\\conda.lnk', '/C', 'C:\\Users\\...test.cmd']' returned non-zero exit status 1.
I feel like I am missing something obvious here, perhaps about the syntax or limitations of subprocess. Any guidance would be appreciated

When you use subprocess.run() with shell=True, the arguments you give it as part of your cmds list are passed directly to the shell, rather than as arguments to the initial command.
So if you intend to pass '/C' and 'C:\\Users\\...test.cmd' as arguments to path, you should either not declare shell=True (preferred) or provide your cmds as a single, space-separated string (less preferred), like path+' /C C:\\Users\\...test.cmd' or ' '.join(cmds).

Getting output of command execution on windowed app

I have created a Python script and compiled it into an exe file with PyInstaller. In the process, I have specified the -w option to get an app that doesn't have any console.
Everything works fine except the execution of commands using popen:
mout = subprocess.Popen(['ls','C:\'])
This line generates an exception [Error 6] The handle is invalid.
I have tried adding the parameters
stdout=subprocess.PIPE, stderr=subprocess.PIPE but it stills not working. I think that is because the main process doesn't have any console assigned. I want to execute the command but without opening any shell, it has to be transparent to the user.
Is there any option?

This should solve your issue.
proc = subprocess.Popen(['ls','C:\\'], shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.PIPE, creationflags=CREATE_NO_WINDOW)

Popen reading from stdout takes a very very long time

I am trying to capture the output from a shell command (npm --version) however only the first line is read and the process does not end.
import subprocess
proc = subprocess.Popen(['npm', '--version'], stdout=subprocess.PIPE, stderr=subprocess.STDOUT, shell=True)
proc.wait()
for line in proc.stdout:
print(line.decode("utf-8").strip())
print("does not get here?!")
Any idea how I could detect the end of this process?.
If I open a cmd and execute 'npm --version', it ends as expected so I do not know why this done in the above does not end.
Some extra information that maybe of use!...
npm is installed via nvm
this is used to manage node installs via symlinks
npm from what I can see is a .cmd file that executes node?
Running this in python command prompt...
>>> import subprocess
>>> proc = subprocess.Popen(['npm', '--version'], stdout=subprocess.PIPE, stderr=subprocess.STDOUT, shell=True)
>>> proc.wait()
0
>>> proc.stdout.readline()
'6.10.3\n'
>>> proc.stdout.readline()
''
Now the second .readline() takes a very very long time to complete!

Using stdout=PIPE and/or stderr=PIPE in popen.wait() will cause a deadlock. Try using communicate() to avoid that.
This is due to other OS pipe buffers filling up and blocking the child process.
See this documentation on how to use communicate ()
https://docs.python.org/2/library/subprocess.html
Hope I could help!

Can you please share the console output when you manually type on the command prompt please.
The code you have shared works on my machine and i am assuming it may have to do something with the way npm is installed. In any case can you share the output from command console.
Thanks
Pushpa

subprocess popen Python

i am executing a shell script which is starting a process with background option &. The shell script is called from python script which hangs.
Shell script:
test -f filename -d &
python file
cmd =["shellscript","restart"]
proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
stderr=subprocess.PIPE, stdin=subprocess.PIPE, **kwargs)
pid = proc.pid
out, err = proc.communicate()
returncode = proc.poll()
Python file hangs and it won't return out of the python process. Also python process is an automated one.

The call to proc.communicate() will block until the pipes used for stderr and stdout are closed. If your shell script spawns a child process which inherits those pipes, then it will exit only after that process also has closed its writing ends of the pipes or exited.
To solve this you can either
redirect the output of the started subprocess to /dev/null or a logfile in your shell script, e.g.:
subprocess_to_start >/dev/null 2>&1 &
use subprocess.DEVNULL or an open file object for stderr and stdout in your python script and drop the communicate() call if you don't need the output of "shellscript" in python

A comma is missing in your cmd list:
cmd =["shellscript", "restart"]

Subprocess.Popen stuck in Ubuntu

I am calling a command executable in Ubuntu using:
proc = subprocess.Popen(commandarray,
stderr=subprocess.STDOUT, stdout=subprocess.PIPE,
bufsize=0, close_fds=ON_POSIX, env=os.environ.copy())
However, when I run this, it is stuck at this step. Is there something I am missing?