How to put in SU password automatically

Posted on 2002-04-18
Medium Priority
Last Modified: 2010-04-21
How do I construct a UNIX command that will automatically plop the SU password in for me.

My program issues the SU KILL -9 commmand, but then UNIX wants the PASSWORD. I need the command line to automatically put in the PASSWORD and execute the command.
Question by:rbend
LVL 38

Expert Comment

ID: 6952628
Install "expect" to your system, and write an script use

Donload expect and some example script from the following site:


Expert Comment

ID: 6952968
If you need to kick off some command as another user, i would advise to use 'sudo' or some counterpart.

This is more safe. Just suppose that  you offer the ability to include the 'root' password., people can change the "kill -9" by lets say "vi /etc/passwd". See what can happen?

By implementing sudo , you can give individual users access to 'indivual' commands.

Author Comment

ID: 6954886
In my question I actually meant SUDO instead of SU.
However, SUDO still required the password be entered.
Same issue.
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Expert Comment

ID: 6956736
Asking for the password is and option:

Just a "cut and paste" from the sudoers man page:

eg: http://www.courtesan.com/sudo/man/sudoers.html

By default, sudo requires that a user authenticate him or herself before running a command. This behavior can be modified via the NOPASSWD tag. Like a Runas_Spec, the NOPASSWD tag sets a default for the commands that follow it in the Cmnd_Spec_List. Conversely, the PASSWD tag can be used to reverse things. For example:

 ray    rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprmwould allow the user ray to run /bin/kill, /bin/ls, and /usr/bin/lprm as root on the machine rushmore as root without authenticating himself. If we only want ray to be able to run /bin/kill without a password the entry would be:

 ray    rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprmNote, however, that the PASSWD tag has no effect on users who are in the group specified by the exempt_group option.

By default, if the NOPASSWD tag is applied to any of the entries for a user on the current host, he or she will be able to run sudo -l without a password. Additionally, a user may only run sudo -v without a password if the NOPASSWD tag is present for all a user's entries that pertain to the current host. This behavior may be overridden via the verifypw and listpw options.


Expert Comment

ID: 6967677
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Accepted Solution

antons061400 earned 100 total points
ID: 7008252
maybe you should create the script like

kill -9 $*

- set the root to be owner
- set the suid flag

and use the script to kill processes

Expert Comment

ID: 7008348
kind of dangerous script to put on the system ...

Expert Comment

ID: 7017263
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