su using here document

Question

file: test.sh

who
su superuser <<BELUGA
mysuperpassword
BELUGA
who

$ ./test.sh

just waits for input. What am I doing wrong? Is there a way to automate this?

Answer 1

You want to use the "expect" command for passing your username and password.

Note however that what you want to do there smells like a bad approach. Maybe we can halp you better if you elaborate a little more on your original problme you want to solve.

Answer 2

I think it would be a lot better to install/use sudo an with a configuration config that allows NOPASSWD for the specific action you are trying to automate.

It will be much safer to allow a specific command via sudo then it would be to store your root password in a text file somewhere.

Answer 3

Running a script as a user and having it upgrade its permissions to root is probably a bad idea. A better solution would be to run the script as root and have it downgrade its permissions as necessary:

#!/bin/sh
UN=user
whoami
sudo -u $UN whoami

When run as root (assuming user is a valid user) the output should be this:

root
user

However if you really want to have a script run as a user and be able to execute commands as root, there are 2 options that I know of.

1. Use sudo with stored password:

   #!/bin/sh
   whoami
   sudo -S -p "" whoami <<EOF
   mysuperpassword
   EOF
   

   Which will output (when run as 'user'):

   user
   root
   

2. Use sudo with no password.
   Add a list of the commands that you wish to run into the /etc/sudoers file by running visudo as root. For example, to allow user to run the commands apache2ctl and whoami, add the following:

   User_Alias SPECIAL = user
   Cmnd_Alias SPECIAL_COMMANDS = /usr/sbin/apache2ctl, /usr/bin/whoami
   SPECIAL ALL = NOPASSWD: SPECIAL_COMMANDS
   

   Or if you really trust user, if it's you for example, you can allow the user to execute any command without a password:

   user ALL=(ALL) NOPASSWD: ALL
   

   Then when the following script is run by user:

   #!/bin/sh
   whoami
   sudo whoami
   

   It will output:

   user
   root