Running interactive shell script in name of other user

Question

In my shell script (bash) I want to call other shell scripts.
I run my script as user_A. One of these scripts needs special handling:

1. It has to be run as different user (user_B). Password needed here.
2. It is interactive, but not only asks questions but runs another script in name of another user (user_C) using su. I have to enter a password here as well.

I can use su calling this script but its questions have to be answered somehow. I can not enter anything because it prints for each questons "stty: : Not a typewriter"

I'm calling the special script this way

su user_B << ABC
...
special_script
...
ABC

Answer 1

Another option for running scripts as other users is the 'sudo' command, think of it as 'superuser do:' for readability purposes. The -u parameter gives username information. So:

sudo -u user_B special_script

Will prompt for the password for user_B. I've never had a problem with running interactive programs using it. You can manage who can sudo to whom via the visudo command.

Answer 2

You can use sudo and create a sudoers file which allows user_A to run the script as user_B.

a line like:

user_A      ALL = (user_B) NOPASSWD: /usr/share/stuff/ABC

would allow user_A to do something like

sudo -u user_B /usr/share/stuff/ABC

without asking for a password

Answer 3

su attempts to get a password from the terminal and needs a tty device so it can call ioctl to turn off key echoing. Since the standard input is coming from a "here document" (ABC), an attempt to call the ioctl on file descriptor 0 yields "not a tty".

If you must use a here document instead of a bona fide script, do:

cat > /tmp/myscript.$$ <<ABC
#!/bin/sh
...
ABC
chmod +x /tmp/myscript.$$
sudo -u user_B /tmp/myscript.$$

Answer 4

You may want to use expect. Its designed for scripted interaction.

Answer 5

#!/bin/bash

main_for_root(){
    :
}
# ------------------------------------------------------------------------------
abs_path="$(readlink -f `dirname $0`)/$(basename $0)"

# if [ `id -u` != 0 ] ; then
if [ `whoami` != 'root' ] ; then
    echo "[su -] run as root"
    su -c"/bin/bash $abs_path $@"
    exit 0
else
    main_for_root $@
fi

It works for 1 user, so now add 'if ...' for second user