I tried to run the command

echo 'my password' | sudo -S su

hopefully it can automatically goes into a child process as root,
however the command executes with no error but exit the child process
and back to my existing user privilege.

How can I remain at the child process as 'root' without 'exit'ing from the
process.

You could use NOPASSWD flag in sudoers:

Then, you can simply run the sudo without specifying the password.
Hopefully this is a trusted user; otherwise anything like this is dangerous.


Another option is to only allow certain commands; for example:

This will only allow "username" to run "/full/path/command" with sudo without specifying password.

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thanks dc.901 for the reply

I added a line at /etc/sudoers, at # User privilege specification section,


root ALL=(ALL:ALL) ALL
b ALL=(ALL) NOPASSWD:ALL <--- added this line

b is my user name

however, upon reboot,
at b user command window prompt,
I still can't execute commands that require root privilege.

Are you using sudo?

Adding your name to the file does not mean you can just run all commands, it means you can use sudo before commands to indicate you wish to run them with root privileges using no password.

I tried running command 'sudo su' at my username command prompt

it still prompt for password

it seems that the added line to /etc/sudoers has no effect

Enter su (or su -to switch to root's environment) if you want to become root.
you'll be prompted for the root password.

It's not a "child process"...it's a new instance of the shell as if you'd logged in with root to begin with.

sudo is not required or involved to become root.

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To add to what scasey has said.

sudo is not intended to be used to login as root, but to grant you root privileges for one command.

For instance, editing /etc/profile. This file is owned by root and does not have write privileges for other users. Therefore to change it you would need root privileges. To do that you would use the sudo command prefix as part of the call to edit the file:

Close.

The program sudoedit will invoke your favorite editor but run as a normal user and work from a temporary copy of the file. Only after the temporary file is saved and the editor exited will it then replace the original file. That's much safer.

I tried command 'su',
it prompts for password, but this password is different from my username password, and I am not sure what it is,
I tried with guess it could be 'toor' but failed to authentical.

raymond0517, what problem are you trying to solve as root?

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I merely want to run commands with root privileges without having to key in password at every session,
if cannot be done, then I would like to run a simple script to automatically enter the sudo password

Then run "sudo passwd", once, and supply a password for the root account. Then connect to it with "su -l"

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Please look at the manual page for the su command. The full name of it is "Switch User". The default user to switch to is root.

You would not use the sudo command to perform the su command. You would just type su and then after that you would be asked for the root password. After successful entry of the root password, your terminal session would then be logged in as root.

Sudo allows you to USE root privileges for the duration of the command you are entering. One exception to this is that you do not use the sudo command modifier for the default su command.

An example of what exact commands?

I managed to change root password using 'sudo passwd'
thanks.

However, when I type su, it again prompt for password.

So I tried "echo 'rootpasswd' | su"

it returns "su: must be run from a terminal" error message.

I am trying to create an automatic login to root, but not allowed