I got a requirement to automate in shell script for sudo su -<someuser> which asks for password.

How to provide password directly to the sudo su - in shell scripting for IBM AIX servers. I have tried using echo <password> | sudo su -<someuser> it did not work. kindly help on this.

3 Answers 3


Use -S

man sudo:

-S, --stdin Write the prompt to the standard error and read the password from the standard input instead of using the terminal device. The password must be followed by a newline character.

so you can use:

echo <myPassword> | sudo -S su <someuser>

Edit: This above did not work on a testing Ubuntu. It seems like the second command "su " is to fast after prompting password query.

I did a workaround to wait a second so the echoed password could be filled in, and then second sudo should be able, to run sudo su - foobar:

echo "password" | sudo -S sleep 1 && sudo su - foobar
  • In my Debian su exits. However sudo su - invoked just after works thanks to cached credentials. It may be a workaround if you can rely on this behavior. Aug 24, 2018 at 6:20
  • it is not working.
    – raamsaara
    Aug 28, 2018 at 12:02
  • @raamsaara: what did exactly not work? did you get an error? meanwhile I edited my answer to add a workaround, which worked on my machine.
    – chloesoe
    Aug 28, 2018 at 13:04
  • Works great with Ubuntu 20.04. Thanks! Dec 1, 2021 at 12:20

With expect. A stub command may be like this:

expect -c '
 log_user 0
 spawn /usr/bin/sudo su - someuser
 expect "*: "
 send "thepassword\n"

See this answer to a similar question.

Another approach is with sudo -A.

  1. Create a file, say pass.
  2. Make the file accessible only to you: chmod go-rwx pass.
  3. Make it executable to you: chmod u+x pass
  4. Edit the file and make it a script that prints your password:

    printf '%s\n' 'yourpassword'
  5. Now you can do this:

    SUDO_ASKPASS="./pass" sudo -A su - someuser

Note: in this case you provide password for sudo (not for su); use the one sudo wants.

  • Thanks . But where can i incorporate the <someuser>
    – raamsaara
    Aug 28, 2018 at 12:05
  • @raamsaara In su syntax. Answer improved. Aug 28, 2018 at 14:53

Can you use the :NOPASSWD option of sudo so you don't need a password. Like: %wheel ALL=(ALL) NOPASSWD: ALL in /etc/sudoers

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