1

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?

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2
  • Most programs read the password from the current tty, not from stdin. (This also lets you do things such as pipe a binary file to a su'd command.)
    – user1686
    Mar 24, 2010 at 18:10
  • 1
    Note that the su command would not execute the second who - even if you managed to get past the password issue. It would either process the command given on its command line ('-c "command arg1 arg2"') or it would go interactive. Commands asking for a password usually read from your tty rather than from standard input - which means you have to fake it out (probably with 'expect' and a pseudo-tty).
    – Jonathan Leffler
    Mar 25, 2010 at 3:51

3 Answers 3

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3

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.

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4

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.

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3
  • With Solaris, pfexec can be used instead of sudo, which isn't installed by default and has some limtations RBAC have not.
    – jlliagre
    Mar 24, 2010 at 21:23
  • some limitations RBAC has not. sorry for the typos. <useless rant> Why isn't edit allowed after such a short period of time ?</useless rant>
    – jlliagre
    Mar 24, 2010 at 21:57
  • 1
    @jlliagre: If editing is locked out, I copy my original comment to the clipboard, delete the comment, create a new blank comment, paste the old comment from the clipboard, then edit it how I wanted to edit the original.
    – Alex
    Mar 25, 2010 at 5:12
2

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
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