How do I run a Python script from a C shell without specifying whole path?

I would like to run a Python script from a Hamilton C shell without having to specify the whole path of the script.

The first thing I tried was to add my scripts folder to the PATH environment variable in Windows. This worked, but the C shell cannot simply execute the .py files automatically, so I have to use "python" before the name of the script.

Now the problem is that since my scripts folder is not a Python path it is not recognized by the Python executable. So this does not work either.

I also tried to add my folder to the "PYTHONPATH" environment variable (which I had to create), but this does not work either.

Is there a way that I can run my script by either simply calling its name (myscript.py) or "python myscript.py"?

Solution 1:

Run Python scripts from Windows command line with script name only

Is there any way that I can run my script by either simply calling its name (myscript.py) or "python myscript.py"?

Absolutely, you can do this in Windows with no problem. I tested this and confirmed it works as expected with Windows 10 as a matter of fact by following the below steps.

Configure Windows File Association Pointers

^{Set the python.exe full explicit path as in the below #3 for the
correct value where this is on your system}

Open up an elevated [cmd.exe] command prompt as administrator
Type in ASSOC .py=PythonScript and press Enter
Type in FTYPE PythonScript="C:\Program Files\Python\python.exe" "%1" %* and press Enter
Type in SET PATHEXT=.py;%PATHEXT% and press Enter

Confirm and Test Windows File Association Pointers

Now from a command prompt you can simply type in the full path to a python script and then press Enter, and the python logic should run accordingly.

You can optionally just type in the full path minus the .py file extension. You could also just CD to the directory where a python script is located, and then type in the script name (with or without the extension) and press Enter, and python should run the script logic accordingly.

Examples from CMD (post above changes)

"C:\ScriptPath\scriptname.py" and press Enter
"C:\ScriptPath\scriptname" and press Enter
CD /D "C:\ScriptPath\scriptname.py" and press Enter
CD /D "C:\ScriptPath\scriptname.py" and press Enter

Execute from Shell with Script Name only

If you really need to run the script from the command line without telling the shell the full explicit path to the python script file, then you need to add the path where this script resides to the %PATH% environmental variable.

Open up an elevated [cmd.exe] command prompt as administrator
Type in SET PATH=%PATH%;C:\Program Files\Python where the C:\Program Files\Python is the value where this exist on your system.

Now you can just type in the script name with or without the file extension without doing a CD to another directory or explicitly specifying the full path to the python script.

Further Resources

Windows Environment Variables

FTYPE /?

Displays or modifies file types used in file extension associations

FTYPE [fileType[=[openCommandString]]]

  fileType  Specifies the file type to examine or change
  openCommandString Specifies the open command to use when launching files
                    of this type.

Type FTYPE without parameters to display the current file types that
have open command strings defined.  FTYPE is invoked with just a file
type, it displays the current open command string for that file type.
Specify nothing for the open command string and the FTYPE command will
delete the open command string for the file type.  Within an open
command string %0 or %1 are substituted with the file name being
launched through the assocation.  %* gets all the parameters and %2
gets the 1st parameter, %3 the second, etc.  %~n gets all the remaining
parameters starting with the nth parameter, where n may be between 2 and 9,
inclusive.  For example:

    ASSOC .pl=PerlScript
    FTYPE PerlScript=perl.exe %1 %*

would allow you to invoke a Perl script as follows:

    script.pl 1 2 3

If you want to eliminate the need to type the extensions, then do the
following:

    set PATHEXT=.pl;%PATHEXT%

and the script could be invoked as follows:

    script 1 2 3

ASSOC /?

Displays or modifies file extension associations

ASSOC [.ext[=[fileType]]]

  .ext      Specifies the file extension to associate the file type with
  fileType  Specifies the file type to associate with the file extension

Type ASSOC without parameters to display the current file associations.
If ASSOC is invoked with just a file extension, it displays the current
file association for that file extension.  Specify nothing for the file
type and the command will delete the association for the file extension.

Solution 2:

I'm the author of Hamilton C shell. It sounds like you're using Cygwin with my C shell and getting the following error when you try to use python:

1 C% python
csh(C:\cygwin64\bin\python line 1):  Couldn't open 'symlink' as a redirected standard input.
> in C:\cygwin64\bin\python
< called from line 1

The problem is that the Cygwin python command is a Cygwin-only symbolic link file rather than an actual executable. They're only supported by Cygwin. (You may have noticed that cmd.exe won't run it either.) Here's what's in it:

2 C% whereis python
C:\cygwin64\bin\python
3 C% cat `!!`
cat `whereis python`
!<symlink>python2.7.exe

Not being able to recognize it as anything else, the C shell tried to interpret it as a script, thought it recognized a !< C shell i/o redirection operator but could not find a file named symlink, hence the error message.

But given that all that file is doing is redirecting you to the actual executable, you can do the same thing with a C shell alias which you can save in your startup.csh file:

4 C% alias python python2.7
5 C% python
Python 2.7.10 (default, Jun  1 2015, 18:05:38)
[GCC 4.9.2] on cygwin
Type "help", "copyright", "credits" or "license" for more information.
>>> quit()
6 C% cd desktop
7 C% cat MyScript.py
print("Hello")
8 C% python MyScript.py
Hello

If you'd like to run your python scripts directly from the C shell without having to type the python command, the C shell supports the common #! syntax to tell it to use the python interpreter. But notice it still needs the name of the actual executable. Here's an example:

9 C% cat MyScript2.py
#!python2.7
print("Hello")
10 C% MyScript2.py
Hello
11 C%