Automatically filling in answers to interactive shell command questions

[Ted Weatherly]

Is it possible to use python to automatically fill in the answers to
interactive shell command questions? For example, I am using a shell
command addperson that behaves as follows:

> addperson

First Name: Ted
Birthday: 12/08/1977
Height: 6'0"
Location: San Francisco, CA

>

I am prompted for "First Name: " and I enter "Ted". I am prompted for
"Birthday: " and I enter "12/08/1977". Imagine doing this for 100
people or more...it gets tiresome.

Assuming I can't change the addperson command to read data from a
file, is there any way to use python to fill in the data for the
expected questions? Perhaps a different language would be better?

-Ted

 

[Jegenye 2001 Bt]

If you use Linux then "expect" (a Tcl thing) is written just for this.

 

[Trent Mick]

Check out pexpect, a Python version of the popular Tcl-land Expect
program:
http://pexpect.sourceforge.net/

I haven't used it but I get the feeling that pexpect is Un*x-only if
that affects you at all.

Trent

[Ted Weatherly wrote]

 

[Ravi]

Is it possible to use python to automatically fill in the answers to
interactive shell command questions? For example, I am using a shell
command addperson that behaves as follows:

First Name: Ted
Birthday: 12/08/1977
Height: 6'0"
Location: San Francisco, CA

I am prompted for "First Name: " and I enter "Ted". I am prompted for
"Birthday: " and I enter "12/08/1977". Imagine doing this for 100
people or more...it gets tiresome.

Assuming I can't change the addperson command to read data from a
file, is there any way to use python to fill in the data for the
expected questions? Perhaps a different language would be better?

-Ted

As a last resort, you can always use PExpect. It pretends to be a user
sitting at a terminal. http://pexpect.sf.net

Ravi

 

[Jp Calderone]

Is it possible to use python to automatically fill in the answers to
interactive shell command questions? For example, I am using a shell
command addperson that behaves as follows:

First Name: Ted
Birthday: 12/08/1977
Height: 6'0"
Location: San Francisco, CA

I am prompted for "First Name: " and I enter "Ted". I am prompted for
"Birthday: " and I enter "12/08/1977". Imagine doing this for 100
people or more...it gets tiresome.

Assuming I can't change the addperson command to read data from a
file, is there any way to use python to fill in the data for the
expected questions? Perhaps a different language would be better?

Ahh, but addperson already reads data from a file! stdin! Have you
tried:

cat answer_file | addperson

or even

addperson < answer_file

or, to keep it Python related,

Jp

 

[Erik Max Francis]

Is it possible to use python to automatically fill in the answers to
interactive shell command questions? For example, I am using a shell
command addperson that behaves as follows:

First Name: Ted
Birthday: 12/08/1977
Height: 6'0"
Location: San Francisco, CA

I am prompted for "First Name: " and I enter "Ted". I am prompted for
"Birthday: " and I enter "12/08/1977". Imagine doing this for 100
people or more...it gets tiresome.

Assuming I can't change the addperson command to read data from a
file, is there any way to use python to fill in the data for the
expected questions? Perhaps a different language would be better?

expect was designed for this. If the addperson program doesn't require
an interactive shell, you can get away with it with something as simple
as:

addperson <<EOF
Ted
12/08/1977
6'0"
San Francisco, CA
EOF

Or by putting these one per line in a file,

addperson < people.data

One certainly _could_ use Python for this, but in this case there are
probably better (and much simpler) tools for the job.

 

[Antti Kaihola]

import os
Would this work:

import os, shutil
shutil.copyfileobj(file('answer_file'), os.popen('addperson', 'w'))

 

[Ted Weatherly]

Thanks for all the useful suggestions!

I tried both approaches, piping to STDIN using 'addperson < person.data' and
using a pexpect script (below), and both work well. Using pexpect hides all
the STDOUT text, and piping to STDIN displays the STDOUT text (but doesn't
show the answers provided).

Some of the questions for my 'addperson' command are conditional...ie.
sometimes 'Birthday: ' is asked and sometimes it isn't. Therefore, pexpect
is a better fit for me.

Thanks again!

-Ted

PS> The actual command I was using is different. Regardless, this python
script should do the trick (it might have some minor flaws):

#!/usr/bin/env python
# addperson.py
"""This automatically answers questions when running addperson
"""

import pexpect
import re

# Store list of answers about each person
answers = [
['Ted', '12/08/1977', '6\'0"', 'San Francisco, CA'],
['Jesus', '12/25/0000', '6\'2"', 'Bethleham'],
['Satan', 'n/a', 'n/a"', 'Hell'],
]

# Iterate over all the people
for a in answers:
done = 0
child = pexpect.spawn ('/usr/sbin/addperson')
# Iterate over all the questions for the command
while not done:
i = child.expect (['First Name: ',
'Birthday: ',
'Height: ',
'Location: '])
if i>=0 or i<=3:
# Send answer for this question
child.sendline (a)
#print 'Answered question #'+str(i+1)
if i==3:
done = 1
print 'Done with'+str(a[0])