Why my program (using pexpect to switch user) doesn't work well?

[BlackjadeLin]

I'm new to python
I want to write a simple script to switch user,for example,from user_A
to user_B.
This my codes:

#!/usr/bin/python
import pexpect
import os
passwd="user_B"
child = pexpect.spawn('su user_B')
child.expect('Password:')
child.sendline(passwd)
child.expect('$')
child.close()

Maybe it's the easiest pexpect program.Sometimes ,it work well,it
switch to user_B successfully .But after i type the command exit to
switch back to user_A,execute the python script again,it can't work,do
nothing or just waiting.Why it have different results?
Sorry for my poor English,and many thanks to all.

Blackjade

[Noah]

On Jan 10, 12:59 am, BlackjadeLin <[e-mail]:

I'm new to python
I want to write a simple script to switch user,for example,from user_A
to user_B.
This my codes:

#!/usr/bin/python
importpexpect
import os
passwd="user_B"
child =pexpect.spawn('su user_B')
child.expect('Password:')
child.sendline(passwd)
child.expect('$')
child.close()

Maybe it's the easiest pexpect program.Sometimes ,it work well,it
switch to user_B successfully .But after i type the command exit to
switch back to user_A,execute the python script again,it can't work,do
nothing or just waiting.Why it have different results?
Sorry for my poor English,and many thanks to all.

Blackjade

When you call child.close() that will kill the child process.
Possibly you want to use the interact() method.
It is not clear from your message if you want to interact with
the child process as if it were your new shell. If you do,
then take a look at the interact() method.

#!/usr/bin/python
importpexpect
import os
passwd="user_B"
child =pexpect.spawn('su user_B')
child.expect('Password:')
child.sendline(passwd)
child.expect('$')
child.interact()

--
Noah

[BlackjadeLin]

On Jan 11, 1:49 am, Noah <[e-mail]:

On Jan 10, 12:59 am, BlackjadeLin <[e-mail]:

I'm new to python
I want to write a simple script to switch user,for example,from user_A
to user_B.
This my codes:

#!/usr/bin/python
importpexpect
import os
passwd="user_B"
child =pexpect.spawn('su user_B')
child.expect('Password:')
child.sendline(passwd)
child.expect('$')
child.close()

Maybe it's the easiest pexpect program.Sometimes ,it work well,it
switch to user_B successfully .But after i type the command exit to
switch back to user_A,execute the python script again,it can't work,do
nothing or just waiting.Why it have different results?
Sorry for my poor English,and many thanks to all.

Blackjade

When you call child.close() that will kill the child process.
Possibly you want to use the interact() method.
It is not clear from your message if you want to interact with
the child process as if it were your new shell. If you do,
then take a look at the interact() method.

#!/usr/bin/python
importpexpect
import os
passwd="user_B"
child =pexpect.spawn('su user_B')
child.expect('Password:')
child.sendline(passwd)
child.expect('$')
child.interact()

--
Noah

Thank you very much!
The interact() method complete my achievement.