This question already has answers here:
When to use Shell=True for Python subprocess module [duplicate]
(2 answers)
Python Subprocess Call with variables [duplicate]
(1 answer)
Closed 8 months ago.
I am using Python 2.6 for reasons I cannot avoid. I have run the following tiny bit of code on the Idle command line and am getting an error I do not understand. How can I get around this?
>>> import subprocess
>>> x = subprocess.call(["dir"])
Traceback (most recent call last):
File "<pyshell#1>", line 1, in <module>
x = subprocess.call(["dir"])
File "C:\Python26\lib\subprocess.py", line 444, in call
return Popen(*popenargs, **kwargs).wait()
File "C:\Python26\lib\subprocess.py", line 595, in __init__
errread, errwrite)
File "C:\Python26\lib\subprocess.py", line 821, in _execute_child
startupinfo)
WindowsError: [Error 2] The system cannot find the file specified
>>>
Try setting shell=True:
subprocess.call(["dir"], shell=True)
dir is a shell command meaning there is no executable that you could call. So dir can only be called from a shell, hence the shell=True.
Note that subprocess.call will only execute the command without giving you its output. It will only return the exit status of it (usually 0 when it was successful).
If you want to get the output, you can use subprocess.check_output:
>>> subprocess.check_output(['dir'], shell=True)
' Datentr\x84ger in Laufwerk C: ist … and more German output'
To explain why it works on Unix: There, dir is actually an executable, usually placed at /bin/dir, and as such accessible from the PATH. In Windows, dir is a feature of the command interpreter cmd.exe or the Get-ChildItem cmdlet in PowerShell (aliased to dir).
Related
This question already has answers here:
Calling the "source" command from subprocess.Popen
(9 answers)
Closed 8 months ago.
I am tasked with automating the process of running bash script using python. Unfortunately I am not responsible for the bash script itself, so I have no idea how it works. When I run the script directly in the terminal using source adastralrc.sh , it works perfectly and gives the desired output.
However when I try to get python to run the file by using subprocess and the exact same command as the argument:
import subprocess
commands = ['source' , 'adastralrc.sh']
p = subprocess.run(commands)
I get the following error:
Traceback (most recent call last):
File "test2.py", line 6, in <module>
p = subprocess.call(commands)
File "/usr/lib64/python3.6/subprocess.py", line 287, in call
with Popen(*popenargs, **kwargs) as p:
File "/usr/lib64/python3.6/subprocess.py", line 729, in __init__
restore_signals, start_new_session)
File "/usr/lib64/python3.6/subprocess.py", line 1364, in _execute_child
raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'source adastralrc.sh': 'source adastralrc.sh'
(venv-c3dns) [vivegab#adl20213d1bld01 vivegab] (cth01/dns_mano_dev)
I am fairly inexperienced with subprocess but I thought that it was just an improved version of os.system() and should just enter the commands as if they were being typed by a person. So why am I getting the error above and what can be done to fix this?
def shell_source(script):
"""Sometime you want to emulate the action of "source" in bash,
settings some environment variables. Here is a way to do it."""
import subprocess, os
pipe = subprocess.Popen(". %s; env" % script, stdout=subprocess.PIPE, shell=True)
output = pipe.communicate()[0]
env = dict((line.split("=", 1) for line in output.splitlines()))
os.environ.update(env)
shell_source(adastralrc.sh)
Looks like a duplicate
This question already has answers here:
Python subprocess.run('ls',shell=True) not working on windows
(2 answers)
Closed 1 year ago.
I want to run shell scripts and git-bash commands using subprocess.run(), in python 3.7.4. When I run the simple example on the subprocess documentation page this happens:
import subprocess
subprocess.run(["ls", "-l"])
Traceback (most recent call last):
File "<input>", line 1, in <module>
File "C:\pycharm\project\envs\lib\subprocess.py", line 472, in run
with Popen(*popenargs, **kwargs) as process:
File "C:\pycharm\project\envs\lib\subprocess.py", line 775, in __init__
restore_signals, start_new_session)
File "C:\pycharm\project\envs\lib\subprocess.py", line 1178, in _execute_child
startupinfo)
FileNotFoundError: [WinError 2] The system cannot find the file specified
# it also fails with shell=True
subprocess.call(["ls", "-l"], shell=True)
'ls' is not recognized as an internal or external command,
operable program or batch file.
1
The message from shell=True is a message from windows cmd, which suggests subprocess is not sending commands to git-bash.
I am using a conda environment located in the project/envs/ folder for python. I have also installed git-bash.
I also tried setting the env and got the same error.
import os
import subprocess
my_env = os.environ.copy()
my_env["PATH"] = 'C:\Program Files\Git\;' + my_env["PATH"]
subprocess.run(['git-bash.exe', 'ls', '-l'], env=my_env)
Traceback (most recent call last):
File "<input>", line 3, in <module>
File "C:\pycharm\project\envs\lib\subprocess.py", line 472, in run
with Popen(*popenargs, **kwargs) as process:
File "C:\pycharm\project\envs\lib\subprocess.py", line 775, in __init__
restore_signals, start_new_session)
File "C:n\pycharm\project\envs\lib\subprocess.py", line 1178, in _execute_child
startupinfo)
FileNotFoundError: [WinError 2] The system cannot find the file specified
I can get it to run by pointing at the git-bash.exe, but it returns an empty string instead of the files in my directory
import subprocess
subprocess.run(['C:\Program Files\Git\git-bash.exe', 'ls', '-l'], capture_output=True)
CompletedProcess(args=['C:\\Program Files\\Git\\git-bash.exe', 'ls', '-l'], returncode=0, stdout=b'', stderr=b'')
I would appreciate any advice on the best way to get this working as shown on the subprocess documentation page.
I found that I can run commands using ...Git\bin\bash.exe instead of the ...\Git\git-bash.exe, like this:
import subprocess
subprocess.run(['C:\Program Files\Git\\bin\\bash.exe', '-c','ls'], stdout=subprocess.PIPE)
CompletedProcess(args=['C:\\Program Files\\Git\\bin\\bash.exe', '-c', 'ls'], returncode=0, stdout=b'README.md\n__pycache__\nconda_create.sh\nenvs\nmain.py\ntest.sh\nzipped\n')
Try this
p = subprocess.Popen(("ls", "-l"), stdout=subprocess.PIPE)
nodes = subprocess.check_output(("grep"), stdin=p.stdout)
p.wait()
ls is Linux shell command for listing files and directories
dir is Windows command line command for listing files and directories
Try to run dir in Windows command line. If it works, try to run the same command using python subprocess:
import subprocess
subprocess.run(["dir"])
For a machine with Windows Operating System, Try the following
import subprocess
subprocess.run(["dir", "/p"], shell=True)
"ls" is replaced with "dir", "-l" is replaced with "/l" and the "shell" is set to true
For a machine with Linux/Mac Operating System, Try the following
import subprocess
subprocess.run(["ls", "-l"])
This question already has answers here:
Cannot find the file specified when using subprocess.call('dir') in Python
(2 answers)
Closed 27 days ago.
I'm trying to use the subprocess module in visual sutdio code but I keep getting an error. Here is the code:
import subprocess
subprocess.run("dir")
or
import subprocess
subprocess.run("dir","/p")
and the error is:
Traceback (most recent call last):
File "e:\Dropbox (Personal)\My Python\external\extrprg.py", line 2, in <module>
subprocess.run("dir")
File "E:\Users\klo\AppData\Local\Programs\Python\Python37-32\lib\subprocess.py", line 472, in run
with Popen(*popenargs, **kwargs) as process:
File "E:\Users\klo\AppData\Local\Programs\Python\Python37-32\lib\subprocess.py", line 775, in __init__
restore_signals, start_new_session)
File "E:\Users\klo\AppData\Local\Programs\Python\Python37-32\lib\subprocess.py", line 1178, in _execute_child
startupinfo)
FileNotFoundError: [WinError 2] The system cannot find the file specified
I'd expect python to run dir and give me a list of the folders in the directory
dir is a command in cmd.exe, which means you want to do:
subprocess.run(['cmd.exe', '/c', 'dir'])
Here's my copy.py:
from subprocess import call
call("copy p2.txt p3.txt")
If in command prompt I use
copy p2.txt p3.txt it copies fine.
but when I use python copy.py it gives me:
Traceback (most recent call last):
File "copy.py", line 2, in <module>
call("copy p2.txt p3.txt")
File "C:\Python27\lib\subprocess.py", line 493, in call
return Popen(*popenargs, **kwargs).wait()
File "C:\Python27\lib\subprocess.py", line 679, in __init__
errread, errwrite)
File "C:\Python27\lib\subprocess.py", line 896, in _execute_child
startupinfo)
WindowsError: [Error 2] The system cannot find the file specified
If I replace the python call to copy with xcopy, it works fine.
Why would this be?
When subprocess.call()ing a command like in a shell, you'll need to specify shell=True as well.
from subprocess import call
call("copy p2.txt p3.txt", shell=True)
The reason you need to use shell=True in this case is that the copy command in Windows is not actually an executable but a built-in command of the shell (if memory serves right). xcopy on the other hand is a real executable (in %WINDIR%\System32, which is usually in the %PATH%), so it can be called outside of a cmd.exe shell.
In this particular instance, shutil.copy or shutil.copy2 might be viable alternatives.
Please note that using shell=True can lead to security hazards, or as the docs put it:
Warning: Using shell=True can be a security hazard. See the warning under Frequently Used Arguments for details.
So i am running into a problem using subprocess.call() and i think i may just be calling it wrong. I am using:
subprocess.call('testingosfile.py')
and i get the traceback:
Traceback (most recent call last):
File "<pyshell#14>", line 1, in <module>
subprocess.call('testingosfile.py')
File "C:\Python27\lib\subprocess.py", line 493, in call
return Popen(*popenargs, **kwargs).wait()
File "C:\Python27\lib\subprocess.py", line 679, in __init__
errread, errwrite)
File "C:\Python27\lib\subprocess.py", line 893, in _execute_child
startupinfo)
WindowsError: [Error 193] %1 is not a valid Win32 application
and the contents of testingosfile.py is:
print "hello world!"
raw_input('....')
how do i manage to get this running?
Thank you in advance for your replies.
The error message makes perfect sense - with subprocess, you can only start an executable. So, to fix it, you should start an executable. Specifically, you should start the Python interpreter and tell it to run your script. Something like
subprocess.call(['python.exe', 'testingosfile.py'])
should work, although you might have to provide the full path to the Python interpreter (I can't test at the moment).
However, have you considered importing testingosfile.py instead? Whenever you import a Python script, all the commands in that script are run. Using
import testingosfile
inside a function in order to execute the commands would be poor style, but you could package up the useful commands of testingosfile.py into some function. Then, you could use
import testingosfile
at the top of your main script, and just call that function whenever you want to print Hello World and get the user's input.
try subprocess.call("myfile.ext", shell=True)