Creating a Terminal Program with Python

Question

I recently started learning python. I have created some basic webapps with Django and wrote some simple scripts. After using VIM as a Python IDE I really fell I love with "Terminal programs" (is there an official term for this?). Right now I am capable of doing simple things like asking someones age and printing it to the screen. However this comes down to running a .py script and after this script is done the normal bash return. I would like create a program that I can run from the command line and that would allow the same user experience as VIM (one that you open and close). For example I created a simple script to import RSS feeds. It would be cool if I could open my terminal type the name of my program -> program would open -> Then I would like to use commands like :findsomething. Basically have real interaction with my program.

To conclude:

• How would I go about creating such a program?
• What kinds of modules, books or site would you recommend

Answer 1

On a *nix system (linux/unix),
if you:

$ chmod 0744 your_file.py  -rwxr--r--   your_file.py 

and add the path to python as the first line of your_file.py:

#!/usr/bin/python 

or (in my case):

#!/usr/local/bin/python 

Once you do that, instead of running it like this:

$ python your_file.py 

You can run it like this:

$ ./your_file.py 

or even rename it to yourfile and run it like this:

$ ./yourfile 

and if you then copy yourfile to your bin (i.e. #!/usr/bin/, or #!/usr/local/bin/) you can run it like this:

$ yourfile 

Then you can...

Use raw_input() to solicit and get input from you user.

your_file.py:

#!/usr/local/bin/python  import os  while(True):     # cntrl-c to quit     input = raw_input('your_prompt$ ')     input = input.split()     if input[0] == 'ls':         dire = '.'         if len(input) > 1:             dire = input[1]         print('\n'.join(os.listdir(dire)))     else:         print('error') 

your_file.py use example:

$ chmod 744 your_file.py  $ cp your_file.py /usr/local/bin/your_file  $ your_file  your_prompt$ ls list_argv.py your_file.py your_ls.py your_subprocess.py your_prompt$ ls . list_argv.py your_file.py your_ls.py your_subprocess.py your_prompt$ pwd error your_prompt$ ^CTraceback (most recent call last):   File "/usr/local/bin/your_file", line 7, in <module>     input = raw_input('your_prompt$ ') KeyboardInterrupt $ 

Grab arguments with sys.argv from the command line when you run your script:

list_argv.py:

#!/usr/local/bin/python  import sys  print(sys.argv) 

list_argv.py use example:

$ python list_argv.py  ['list_argv.py'] $ python list_argv.py hello ['list_argv.py', 'hello'] $ python list_argv.py hey yo ['list_argv.py', 'hey', 'yo']  $ chmod 744 list_argv.py  $ ./list_argv.py  ['./list_argv.py'] $ ./list_argv.py hi ['./list_argv.py', 'hi'] $ ./list_argv.py hey yo ['./list_argv.py', 'hey', 'yo']  $ cp list_argv.py /usr/local/bin/list_argv $ list_argv hey yo ['/usr/local/bin/list_argv', 'hey', 'yo'] 

Replace raw_input() with sys.argv.

'your_ls.py':

#!/usr/local/bin/python  import sys import os  dire = '.' if len(sys.argv) > 1:     dire = sys.argv[1] print('\n'.join(os.listdir(dire))) 

'your_ls.py' use example:

$ chmod 744 your_ls.py  $ cp your_ls.py /usr/local/bin/your_ls $ your_ls  list_argv.py your_file.py your_ls.py your_subprocess.py $ your_ls . list_argv.py your_file.py your_ls.py your_subprocess.py $ your_ls blah Traceback (most recent call last):   File "/usr/local/bin/your_ls", line 9, in <module>     print('\n'.join(os.listdir(dire))) OSError: [Errno 2] No such file or directory: 'blah' 

Use subprocess.Popen to access anything you could from the command line.

your_subprocess.py:

#!/usr/local/bin/python  import os import subprocess  while(True):     # cntrl-c to quit     input = raw_input('your_prompt$ ')      process = subprocess.Popen(input, shell=True,                            stdout=subprocess.PIPE,                            stderr=subprocess.PIPE)      out, err = process.communicate()      print(out)     print(err) 

your_subprocess.py use example:

$ chmod 744 your_subprocess.py  $ cp your_subprocess.py /usr/local/bin/your_subprocess $ your_subprocess  your_prompt$ ls list_argv.py your_file.py your_ls.py your_subprocess.py   your_prompt$ ls . list_argv.py your_file.py your_ls.py your_subprocess.py   your_prompt$ pwd /Users/ox/_workspace/cmd_ln   your_prompt$ blah  /bin/sh: blah: command not found  your_prompt$ ^CTraceback (most recent call last):   File "/usr/local/bin/your_subprocess", line 8, in <module>     input = raw_input('your_prompt$ ') KeyboardInterrupt $ 

BREAK STUFF!

:-D

HAVE FUN!

-ox