I am writing a Python script on Windows, that needs to work on a Red Hat Linux machine. On Windows,
os.path.abspath(os.curdir)
returns something like
C:\Users\Me\...\CurrentDirectory
without a trailing \ .
I'm unable to run it on Linux, but to my knowledge it would be more like
/home/Me/.../CurrentDirectory
with the slashes going the other way, and I'm uncertain about a trailing / . First of all, is there one? Secondly, how do I deal with this issue? The script doesn't have to work on both Windows and Linux, just Linux, in the end. Though I can only test it on Windows :(
It shouldn't matter if you use os.path.join()
See:
Python os.path.join on Windows
Why doesn't os.path.join() work in this case?
The behavior would be more or less the same across the OS. Instead of using \ or / use
os.sep
inside your code. Do not try to hardcode anything
Related
I'm writing a program that executes short shell one liners (potentially including pipes and background tasks etc), and I'd like to make it "just work" cross platform as much as possible.
For mac/linux the following seems to work well:
shell = os.environ.get("SHELL", "/bin/bash")
subprocess.Popen([shell, "-c", script_content])
However given that on windows:
SHELL isn't usually set
Assuming that bash is installed, a usable bash executable might be found in a variety of different places
What's the best way to make this work as reliably as possible in windows?
Are you looking for C:\Windows\System32\cmd.exe?
And if you are doing cross platorm you could use sys.platorm to find the platform the user is using.
On Window, 'COMSPEC' holds the name of the current command program. You can write unconditional lookup to lookup in the environemnt. Usually, better to take this approach, as in many cases, python script may be executed from 'git-bash', WSL or similar. No need to explicitly program for specific platform.
First Using SHELL
If none, use COMSPEC
See: https://en.wikipedia.org/wiki/COMSPEC
If you have Windows git client installed, you should have git bash, so in a CMD window:
set SHELL="c:\Program Files\Git\bin\bash.exe"
then you can run you python program.
I need to quote a path in a portable way, shlex.quote is converting slashes to / on windows, which causes the command to fail (using the default windows command prompt).
Returning C:/Users/Me/Documents/Projects/Test
Instead of C:\Users\Me\Documents\Projects\Test
How can I quote a path on windows, similar to shlex.quote that uses native slashes, suitable for the windows command prompt and BAT files?
As mentioned by some comments, your problem might not be caused by shlex.quote().
Nevertheless there is the module mslex which provides mslex.quote() and mslex.split() for the Windows shell, just like what shlex provides for the Unix shell.
I am trying to use shutil.which to check if the Linux Subsystem is installed on Windows 10.
Using the Windows where command in Command Prompt, I can see the location of the wsl.exe executable.
C:\Users\spike>where wsl
C:\Windows\System32\wsl.exe
The above shows that WSL does exist, and is in my system PATH.
When I use the which function in Python, it says that the executable was not found.
print(which("wsl")) # Returns None
Just to make sure that which works, I test it on cmd.exe.
print(which("cmd")) # Returns "C:\Windows\System32\cmd.exe"
That works. Well, what if I make a system shell call with the command that did work?
print(system("where wsl")) # Returns 1
Exit code 1, the command wsl was not found.
So I test it on cmd.exe again.
print(system("where cmd")) # Returns 0
Okay, so that does work. What is the problem?
For each Python 3 example assume these imports.
from shutil import which
from os import system
Why can Python not find wsl.exe even though it is proven to exist?
Thanks.
Credit to #eryksun, who helped solve this in the comments.
The issue is that I am using 32 bit Python, and wsl.exe is only in C:/Windows/System32. The problem with this is that Python is looking in C:/Windows/SysWOW64 for the executable instead.
wsl.exe is only 64-bit, and you're looking in SysWOW64 instead of the real System32 because you're using 32-bit Python. – eryksun
Because WSL only supports 64-bit systems, I ended up just running my code with 64-bit Python. However, and alternate solution if you only use Py32 would be to access SysWOW64 directly, using the system root environment variable and os.path.join.
In Windows 7+, the real System32 directory is accessible in a 32-bit process as "SysNative". Unfortunately this virtual directory isn't available in a native 64-bit process, so you need to first check whether it exists. For example: sysnative = os.path.join(os.environ['SystemRoot'], 'SysNative'); if os.path.exists(sysnative): .... – eryksun
Now you can install python in 64 bit and everything will work just fine. (Be careful that when the python installer runs, there should be written 64 bit packages and other things as 64 bits [right where the loading bar is])
I use a Mac and I use Shift + Alt + / when I want to type a \. I'm trying to learn Python and as you can see \ works fine, but not in IDLE.
How do I make backslash (\) work in IDLE?
Since this problem still persists on OSX 10.8 with python 2.7.5 and 3.3.2 and since this is the first google hit when searching for backslash idle here is a more practical solution instead of copy and pasting:
Go to:
idle->preferences->keys
Under Action-Keys replace:
expand-word <Option-Key-Slash>
with something you like for instance:
expand-word <Control-Option-Key-Slash>
This should fix it.
go to
idle -> preferences -> General -> default source encoding -> Locale-defined
Copy-Paste it from notepad.
or
Use command line python shell.
In IDLE, it worked with alt (option) + i.
Everyone i have an excellent solution to this problem.
Go to "Terminal":
Write
Python
Now it works because it's like using IDLE just in terminal and in terminal the backslash will work perfectly fine.
I am currently running a Python scripts both on Linux and Windows 7. The file is executed in an execv style with which I mean that the interpreter is defined in the beginning of the file in a command.
In Windows system, the interpreter specification is:
#!C:\Python26\python.exe
However in Linux this needs to be
#!/usr/bin/python
I would like to run this script in both systems without having to change this line again and again.
I have tried out the following:
#!C:\Python26\python.exe
#!/usr/bin/python
as well as:
#!C:\Python26\python.exe;/usr/bin/python
So: is there any way I could specify multiple interpreters?
Depending on what you're trying to do, this might be a bit heavy-weight, but 0install can run your program will the appropriate Python interpreter for your platform. In your program's XML description, do something like this (e.g. if you want Python >= 2.6, < 3):
<command name="run" path="myprog.py">
<runner interface="http://repo.roscidus.com/python/python">
<version not-before="2.6" before="3"/>
</runner>
</command>
See: http://www.0install.net/local-feeds.html
This will also make 0install download a suitable version of Python if the user doesn't have it already.
Note that you may want to do this even if you're only targetting Linux, because with Python 3 there is no single #! line that works on all platforms (some platforms, e.g. Arch, require "python2" not "python", while others, e.g. Debian, don't provide "python2", only "python").
#!/usr/bin/env python
That will call the env program to search your PATH for a Python executable.
If you need to ensure a specific version of Python you can do e.g.:
#!/usr/bin/env python3.11
Is there any way I could specify multiple interpreters ?
You don't need to. On Windows (at least as long as you don't have CygWin or similar installed), the Shebang line is treated as a normal Python comment; that means, it is ignored. Windows knows that it should run .py and .pyw files with the Python interpreter, because it is told that upon installation of Python.