如何在终端中制作 Python 脚本“tab-complete”目录？

Question

I have a Shell Script, let's say run.sh , which reads a user input from keyboard and then does some specific tasks. For some technical reasons I'm migrating this script to Python, eg run.py , in order to achieve the exact same goal.

In the run.sh file I ask the user a input, which is typically a file in the file system, so I gave the option of "tab-completing" it and I achieved it simply through the line:

read -e -p "Choose a file: " file

The -e flag does the job of tab-completing users input. For example, if user's current directory is project , which follows the structure:

project
-- src
-- shared
   -- lib
   -- imgs
      -- image.png
-- include
-- README.txt

and the input file is image.png they could proceed as follow:

sh<tab>i<tab><tab>

the result would be shared/imgs/image.png .

Now how do I achieve it inside a Python script? You may believe there are tons of related questions but I haven't been able to reproduce this exact same result in run.py .

What I have tried so far:

1. Python's os module:

import os

os.system("read -e -p 'Choose a file:'")

Output: sh: 1: read: Illegal option -e

2. Python's subprocess module

import subprocess

subprocess.run(['read', '-e', '-p', 'Choose a file'])

Output:

Traceback (most recent call last):
  File "run.py", line 26, in <module>
    subprocess.run(['read', '-e', '-p', 'Choose a file'])
  File "/usr/lib/python3.7/subprocess.py", line 453, in run
    with Popen(*popenargs, **kwargs) as process:
  File "/usr/lib/python3.7/subprocess.py", line 756, in __init__
    restore_signals, start_new_session)
  File "/usr/lib/python3.7/subprocess.py", line 1499, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'read': 'read'

3. Python's readline module

import readline

readline.parse_and_bind("tab:complete")
file = input("Choose a file: ")

This one almost seems to work, but there is one big issue: it completes only the files in user's current directory. If user hit s<tab> then src and shared show up, but if they hit sh<tab> the lib and imgs directory do not show up.

I'd like some elegant and simple way to achieve this, but I am convinced this might be a little more difficult than expected. Are there any other approaches that can solve this problem?

Answer 1

Set sensible completion delimiters:

import readline

readline.set_completer_delims(' \t\n=')
readline.parse_and_bind("tab: complete")
option = input("Tab complete a file: ")

By default, readline will delimit based on any of the following:

>>> import readline
>>> readline.get_completer_delims()
' \t\n`~!@#$%^&*()-=+[{]}\\|;:\'",<>/?'

Since / is part of this set, anything after a / will be completed independently of anything before it. This obviously makes no sense when you're trying to complete a file path.