I can use python 3 in terminal fine, but I don't know how to make it so terminal will run a program that I have written in python 3.
What do i have to do to associate the .py file extension with python3.2.3 for terminal and not python2.7.1
I am using textwrangler as my text editor, but will happily use any editor if it will run, though I don't think this is my problem as idle doesn't work either and it doesn't have line numbers in it either.
Kind regards
Rob
Add a python3 hashbang to the beginning of your scripts:
#!/usr/bin/env python3
# do stuff
Then, you can make your script executable and run it:
chmod +x script.py
./script.py
try python3 yourprogram.py in your terminal.
or by adding this line on the top of our programs, this is the path to your interpreter:
#!/usr/local/bin/python3.2
Related
I have a .py python script and when I run it typing ./filename.py I obtain a syntax error. However, when I run it typing python filename.py my program executes correctly.
How to make it run correctly typing ./filename.py ? I think it is related to the $PATH variable but I don't have any further idea.
put either a shebang at the start of the file, or run with python
for example:
#!/usr/bin/env python3
or run:
python3 filename.py
I have a python program which I need to run at a particular day of a month, so I am using crontab for this task and create a shell script to run this python program.
This is part of my shell script:
#!/bin/bash
filepath='file2018'
cd ${filepath}
python3 file.py
When I run the crontab which executes the shell script, the log file shows the following error:
line 9: python3: command not found
I'm really confused about why this error occurs because I have already install python3 and I can run python3 directly from the command line.
Besides, if I replace python3 with python, the shell script works! My python version is python2, but I have to use python3 for this program, so I have to use python3 instead of python.
My operating system is Linux CentOS.
Hope someone can give me some tips!
You can give the full path to the python3 executable. You can get it using the which python3 command. Try it out.
in file.py add first line like below and add +x permission to file.py file
#!/usr/bin/python3
it will automatically execute, no need to mention python3 in the script
use "which python3" command to know exact path of python3 in your machine
I have installed Anaconda 2 & 3 in my system. Anaconda 2 contains python 2.7 & Anaconda 3 contains python 3.6.
I need to run my python code using command prompt & I need to use python 3.6
While I'm running python --version, I'm getting python 2.7.14. How do I change it to python 3.6?
As you can see, I have both Python2 and Python3 installed.
I hope you know that the path of the python executable has to be added to the PATH environment variable in Windows. As you can see, the path of Python2 is placed above the path of Python3 in my system.
How does the cmd run commands?
It searches for an executable with the same name in the directory the cmd has been opened in, then goes and searches for the command in the locations provided in the Windows PATH variable, from TOP to BOTTOM.
Which means, it gets the path to Python2 before it can get to the path of Python3. Therefore, every time you type python in your cmd, it runs Python2.
Both Python2 and Python3 executables have the same name in Windows so it never runs python3.
What seems like an obvious solution?
You might think, changing the name of python.exe to python3.exe for the Python3 executable will solve your problem. You are partially right, it will work. But you have to use python3 file.py or python3 --version, which I think, is understandable. But, pip will no longer work if you change the name of the original python executable. You will no longer be able to install external packages and modules.
How can this problem be solved?
You can create an alias for the Python3 executable called python3.bat.
.exe and .bat files can be called from the cmd directly without using their extension. We always write python filename.py instead of python.exe filename.py although both are correct. The same can be done with .bat files.
Go back to the first image and notice the python3.bat file below python.exe. That is my way of calling python3 without renaming my original python executable.
python3.bat
Create a new file using notepad or something and paste this %~dp0python %*
I don't fully understand how this works except that dp0 basically runs python from inside the same directory and %* passes all the arguments to the python executable. Place this file inside your Python3 installation directory and your problem will hopefully be solved.
python3 basically runs your python3.bat file, which in turn runs the python.exe from its folder and passes the arguments to it.
I hope this solves your problem.
You should have python3 also in your path. You could use python3 to run your script:
python3 <your_script>
But to answer your question, you could use alias and update it as python.
$ python --version
Python 2.7.6
$ alias python=python3
$ python --version
Python 3.6.4
If you want to run Python 3.6, then execute python3.6.
Otherwise, check with which python where the symbolic link to the actual python executable is. On my system, it's
/usr/bin/python
and when I ls -la /usr/bin/python, it gives
lrwxrwxrwx 42 user user 42 Aug 24 03:45 /usr/bin/python -> python2.7
If you are really sure that you want to do it, you can now just move the old symlink somewhere:
sudo mv /usr/bin/python /usr/bin/old_python
and create a new symlink:
sudo ln -s /usr/bin/python3.6 /usr/bin/python
Now you should get something like:
$ python --version
Python 3.6.5
I don't guarantee that it doesn't break everything in the world, especially if you have some distro that has a package manager that relies on a specific python version under python.
This seemed to work nicely on Linux Mint 18.
I made a small trick to solve this problem. For me
C:\Python27
and
C:\Python27\Scripts
were at the top of the PATH Environment variable list. I simply selected them and clicked on Moved Down to shift them to the end of the list.
Just make sure that your path of Python3 and its Script folder is above Python2 path.
And it solved the problem for me. Hope it would help you too.
Reason :
How does the cmd run commands?
It searches for an executable with the same name in the directory the cmd has been opened in, then goes and searches for the command in the locations provided in the Windows PATH variable, from TOP to BOTTOM. Which means, it gets the path to Python2 before it can get to the path of Python3. Therefore, every time you type python in your cmd, it runs Python2.
Both Python2 and Python3 executables have the same name in Windows so it never runs python3.
reason is taken from the accepted answer to this question.
In order to run your script with python 3 you can use
python3 <path to file>
P.S.: this should be a comment, but I do not have the required reputation. :)
If Anaconda 3's is the only python3 interpreter in the system you can run python3 instead of python in your command line and it should work.
You can alter PATH parameter inverting the positions of both interpreters.
I have two versions of the python which the first path is python 2(I am still working with python 2), but there are some scripts which should use python 3. This is what I have done:
I have create a bat file.
ex:
open Notepad++ and write :
#echo off
set PYTHONPATH=
"%~dpn0.py" %*
save it as 'yourscriptname.cmd'.
before my script(which should use python3) I just run this file in command line and then run my script. it is working.
#!/usr/bin/env python
I put that at the top of a script. I've seen that should make the script runnable from the command line without the need for python programname.py. Unless I'm misunderstanding I should be able to use programname.py as long as I have the above line at the top of the script. Is this correct?
It isn't working for me I just get an error indicating that I would have to use python at the beginning of the 'call'.
Universal running of Python scripts
You can pretty much universally run without the shebang (#!) with
python myscript.py
Or nearly equivalently (it places the current directory on your path and executes the module named myscript) (preferably do this!):
python -m myscript
from the command line, as long as you have Python installed and on your path environment variable (i.e. set to run with python, which, if installed, would typically be the case).
Shebangs (#!) are a Unix thing.
The shebang, as you're using it, is typically for running on a Unix platform (typically Apple or Linux). Windows would typically require cygwin to use the shebang.
You can usually default to whatever python is available on your system path with:
#!/usr/bin/env python
Assuming you're on a Unix, you might try other locations for your python setup, like:
#!/usr/bin/python
Muddling through
You can see what python you're currently using by using the unix which command, so if you want to see where your python is coming from, use this command:
which python
or on Windows (cygwin probably can run the shebang):
where python
On Linux/Unix, you'll need execution perms to run the file as well, in that manner. Use chmod
chmod +x myscript.py
(chmod also may apply to Cygwin in Windows)
If you're not running as root, you may require sudo, and that would be
sudo chmod +x myscript.py
And then attempt to run (within the same directory) with
./myscript.py
make the file executable
sudo chmod +x /path/to/file.py
and then from the same directory as file.py:
./file.py
I've decided that it would be good for me to move outside of my .NET bubble and start experimenting with other technologies. I have Ubuntu12 running and python2.7 and 3.2 are installed. I can run code directly in the interpreters.
I have a basic script on the filesystem called Standalone.py:
#!/usr/bin/env python3.2
import sys
print("this is a standalone script.")
When I'm at my bash prompt I type $ python3.2 Standalone.py. I get a response saying this is a standalone script. But when I type $ Standalone.py then it tells me that the command is not found.
How do I run such scripts?
Thanks for any help.
update
I changed the permissions of Standalone.py to 755. Then I ran the command:
$ ./Standalone.py
and received the message:
: No such file or directory
I then switched the permissions of Standalone.py back to 644. Then when I ran
$ ./Standalone.py
I received the message
-bash: ./Standalone.py: Permission denied
Is there something I'm missing?
You need to make the script executable using
chmod +x Standalone.py
Usually, the current directory is not searched for executable files, so you need to use
./Standalone.py
to tell the shell that the script is in the current directory.
Make sure your script file has linux newline (just \n) not windows newline (\r\n). Did you write the script on windows? This happened to me once. You should check your editor settings.
Your script should start with #!/usr/bin/python not #!/usr/bin/env python3.2
Make sure you're in the folder where your script is located you can check with ls
chmod +x Standalone.py
./Standalone.py
At first, to excecute a script it need to be executable. So you either have to do a chmod +x $file or a chmod 0740 $file. When you set the file permission to 644 you are putting the execute right away, so if gives you an error. If you are unsure of execution right and octal notation, you can use this : http://permissions-calculator.org/decode/0644/.
To really answer your question then, if you want to call the script with $file.py it needs to be in your PATH variable. You can display it with echo $PATH. Those are the directories that are searched for script to execute. So you simply need to give your script the executable right and put it in one of the directory given by your PATH.
Can you check if /usr/bin/python or /usr/bin/python3.2 exists
Execute below comamnd:
which python3.2
and then use the resulting path on top of you script.