How can I use a Python script in the command line without cd-ing to its directory? Is it the PYTHONPATH?


How can I make any use of PYTHONPATH? When I try to run a script in the path the file is not found. When I cd to the directory holding the script the script runs. So what good is the PYTHONPATH?


$ tree -L 1 "/home/randy/lib/python" 
├── __pycache__
├── scripts

$ python -h
python: can"t open file "": [Errno 2] No such file or directory

$ cd "/home/randy/lib/python"

After cd to the file directory it runs ..

$ python -h
usage: [-h] [-b]

Why can I not make any use of the PYTHONPATH?

Answer rating: 197

I think you"re a little confused. PYTHONPATH sets the search path for importing python modules, not for executing them like you"re trying.

PYTHONPATH Augment the default search path for module files. The format is the same as the shell’s PATH: one or more directory pathnames separated by os.pathsep (e.g. colons on Unix or semicolons on Windows). Non-existent directories are silently ignored.

In addition to normal directories, individual PYTHONPATH entries may refer to zipfiles containing pure Python modules (in either source or compiled form). Extension modules cannot be imported from zipfiles.

The default search path is installation dependent, but generally begins with prefix/lib/pythonversion (see PYTHONHOME above). It is always appended to PYTHONPATH.

An additional directory will be inserted in the search path in front of PYTHONPATH as described above under Interface options. The search path can be manipulated from within a Python program as the variable sys.path.

What you"re looking for is PATH.

export PATH=$PATH:/home/randy/lib/python 

However, to run your python script as a program, you also need to set a shebang for Python in the first line. Something like this should work:

#!/usr/bin/env python

And give execution privileges to it:

chmod +x /home/randy/lib/python/

Then you should be able to simply run from anywhere.

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