Error: su: must be run from a terminal

Question

When I try to login to root user using shell script given below, it throws an error:

su: must be run from a terminal

The srcipt (scriptfile.sh) looks as follows:

su -s <<EOF
echo Now i am root
whoami
EOF

Although I can successfully do su from the terminal, it logs in to the root user by default.

FYI: Same script is working fine when we replace su with sudo. I am running this script as normal user, not as root.

What can be the possible reason for the error and how can I solve this?

Note: I want to get it done without touching /etc/sudoers file.

Solution

Quite likely something down to syntax/interactive shell from what I googled so far, but I am no expert!

Below works for me, even if technically su should not be used in a shell script, sudo is more secure.

This works:

#!/bin/bash
exec su root --command 'echo -e "hello world" >> "/home/parallels/rootWasHere.txt"'

And so does this:

#!/bin/bash

runAsRoot="
printf \"\nhey there\n\"
printf \"\nhello world, I am root\n\" >> \"/home/parallels/rootWasHere.txt\"
"
exec su root -c "$runAsRoot"

Also, in regards to -s option for su, that specifies only the shell according to the manual. This doesn't imply that it will also execute what's passed afterwards/ to -s, so I think you could something on the lines of:

#!/bin/bash

runAsRoot="
printf \"\nhey there\n\"
printf \"\nhello world, I am root and my shell is \$SHELL\n\" >> \"/home/parallels/rootWasHere.txt\"
"
exec su root -s /bin/zsh -c "$runAsRoot"

Comments

[binarysta]

Does this answer your question? login to root user with password inside script only

[Divya Singh]

No. Its a different question entirely. I didn't ask this question over there to avoid mixing up of two topics. If you look into the scripts carefully you will find a very big difference, one uses sudo and the the other uses su. With sudo its working fine, but with su its not. Question has been edited for more clarification

[terdon]

Why are you using -s? What are you trying to achieve with this command? Aren't you getting an su: option requires an argument -- 's' error?

[annahri]

Please elaborate

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