pythonpythonpath

invoking a python script from the command line leads to “[Errno2]" - PYTHONPATH is set

Ignorant new Linux/Ubuntu/StackOverflow user here.

I have my scripts for users to run in a path like /home/user/Projects/scripts/. If that is the pwd, I can invoke a script like this:

~/Projects/scripts$ python2.7 scriptname.py

(I am using python 2.7 because of legacy code.)

I want the users to not be forced to set the pwd to that directory to run scripts, just let them run from /home/user after logging in. Like this:

~$ python2.7 scriptname.py

Also, there are several directories with scripts, I am simplifying for this example.

I edited bash.rc to set PYTHONPATH to include that directory, then logged back in. The environment variable is set, but I can't invoke the script from the home directory. I get

python2.7: can't open file 'script': [Errno2] No such file or directory

sys.path includes the path to the scripts directory. If I start python 2.7 from the home directory and import a script as a module, it finds it:

~$ python2.7
>> import script
>>

But I can't get the command line to find it.

If I include the entire path on the command line, it works:

~$ python2.7 /home/user/Projects/scripts/scriptname.py

Should I be able to do this? What am I doing wrong?

Solution

  • Instead of helping python find the script, you should let the shell find the scripts and let the script find python.

    1. Edit the scripts to begin with the line

      #!/usr/bin/env python2.7

    or if you prefer, write the actual path to python 2.7 like this:

       #!/path/to/the/python2.7

    1. Make the scripts executable:

      chmod +x scriptname.py

    2. Add the directory containing the scripts to the variable PATH (not PYTHONPATH) by putting this in your bash.rc (or .bashrc etc.):

       export PATH="$PATH:/home/user/Projects/scripts"

    3. Start a new shell or terminal session.

    Once you've done that, you'll be able to run your scripts by just typing

    ~$ scriptname.py

    at the prompt.

    1. Optional: At this point you can also rename scriptname.py to scriptname, since the end-users users don't need to worry about what interpreter to run it with.