how to capture the python output in a shell variable from expect?

Question

I want to get the pw value from python, something like

spawn python3 $pscript
expect "password:"
send "$enc_password\r"
set outcome $expect_out(buffer) --getting empty array in outcome

file.py

import keyring
pw = keyring.get_password("system","user")
print(pw)

let me know if there is any other way to do this.

I don't know how to get in `expect` but `pyexpect` has method to get all text `before` expected value - but it needs to use `expect some_text` first. Because `print()` sends `new line` at the end so I would use `new line` to detect end of printed data and later I would use function to get all text `before` new line. — furas, Jul 20 '21 at 11:30
for this script I would try to do it without `expect` but something like `outcome = $(python script.py < file_with_password)` or in the newest `Bash` `outcome = $(python script.py <<< text_with_password)` — furas, Jul 20 '21 at 11:35
Hi @furas Thank you for pointing me in the right direction. I just did the same thing in expect and it worked, answering the question with working code — deba prasad nayak, Jul 20 '21 at 13:16
@furas usually a well implemented app/module would get password directly from the tty so stdin redirection would not work. that's why tools like Expect are created. — sexpect - Expect for Shells, Jul 21 '21 at 03:15

score 1 · Accepted Answer · answered Jul 20 '21 at 13:19

1

I just missed one thing:

spawn python3 $pscript
expect "password:"
send "$enc_password\r"
expect "blah" --this extra expect, else the outcome will be an empty array
set outcome $expect_out(buffer)

answered Jul 20 '21 at 13:19

deba prasad nayak

21
6

you can mark your answer as accepted and few minutes later you can upvote it. – furas Jul 20 '21 at 16:08

how to capture the python output in a shell variable from expect?

1 Answers1