Use sudo without password INSIDE a script - linux

Question

For some reason I need, as user, to run without sudo a script script.sh which needs root privileges to work.
I saw as the only solution to put sudo INSIDE script.sh. Let's take an example :
script.sh :
#!/bin/sh
sudo apt-get update
Of course, if I execute this script, I get a prompt asking me for a password. Then I added to my sudoers file (at the end to override everything else) :
user ALL=(ALL:ALL) NOPASSWD:/path/to/script.sh
By the way, I also tried the line :
user ALL=(ALL) NOPASSWD:/path/to/script.sh
(I think I didn't fully understand the difference)
But this doesn't solve my problem if I don't use sudo to execute this script :
# ./script.sh
[sudo] password for user:
# sudo ./script.sh
Starts updating...
Well, so I say to myself "Ok, that means that if I have a file refered in sudoers as I did, it will work without prompt only if I call him with sudo, what is not what I want".
So, ok, I create another script script2.sh as following :
script2.sh
#!/bin/sh
sudo /path/to/script.sh
In fact it works. But I am not truly satisfied of this solution, particularly by the fact that I have to use 2 scripts for every command.
This post is then for helping people having this problem and searching for the same solution (I didn't find a good post on it), and perhaps have better solutions coming from you guys.
Feel free to share your ideas !
EDIT 1 :
I want to insist on the fact that this "apt-get update" was just an example FAR from whhat my script actually is. My script has a lot of commands (with some cd to root-access-only config files), and the solution can't be "Well, just do it directly with apt-get".
The principle of an example is to help the understanding, not to be excuse to simplify the answer of the general problem.

Answer 1

From my blog: IDMRockstar.com:
The kicker is that sometimes, I need to run commands as root. Here's the quick and dirty way I accomplish that without divulging the passwords:
#! /bin/bash
read -s -p "Enter Password for sudo: " sudoPW
echo $sudoPW | sudo -S yum update
This way the user is prompted for the password (and hidden from terminal) and then passed into commands as needed, so I'm not running the entire script as root =)
If you have a better, way, I'd love to hear it! I'm not a shell scripting expert by any means.
Cheers!
.: Adam

Answer 2

If you want to run sudo /usr/bin/apt-get update without a password, you need to have the sudoers entry:
user ALL=(ALL:ALL) NOPASSWD:/usr/bin/apt-get update
For the larger issue of the script as a whole, there are two possible approaches:
Approach 1
For each command in the script that needs sudo, create a line in sudoers specifically for that command. In this case, the script can be called normally:
./script1.sh
Approach 2
Place a line in sudoers for the script as a whole. When this is done, the individual commands do not need sudo. However, sudo must be used to start the script as in:
sudo ./script.sh

Answer 3

If your password isn't something you want to be very secure about, (maybe some testing server in the company etc.) you can elevate to sudo in the script via echo like:
echo YourPasswordHere | sudo -S Command
The prompt still prints the "enter password" text to output though. So don't expect it to be neat.
See this Askubuntu post

Answer 4

As you noted, the file that must appear in the sudoers configuration is the one that is launched by sudo, and not the one that runs sudo.
That being said, what we often do, is having something like
user ALL=(ALL:ALL) NOPASSWD:/path/to/script.sh
in the sudo configuration, where script.sh has all the commands that the script has to do.
Then we define either a Bash function or an alias so that script.sh is actually
sudo /path/to/script.sh
The only issue is if some commands must not be run as root, you need to insert some su - user -c "command" commands in the script.

Answer 5

In new /etc/sudoers.d/apt-get file, put single line:
user ALL=(ALL:ALL) NOPASSWD:/usr/bin/apt-get update
Fully qualified path to executable is required here.
Then use following in your script:
sudo apt-get update
Here, fully specified name is not required. Sudo uses PATH environment variable for executable resolution.
While changing and checking sudoers configuration, be sure to keep another root session open for error recovery.

Answer 6

I suggest you look at the sudo environment variables - specifically you can use (and check for) $SUDO_USER. Call your script with sudo (1 entry in sudoers), then do user stuff as SUDO_USER and root stuff as root.

Answer 7

As mentioned by Basilevs you need to add your user to the sudoers file in order to avoid that sudo commands in the script get stuck awaiting the password.
On Ubuntu 16, there is a simpler way: just add the user to the sudo group, like this:
sudo usermod -aG sudo *username*
From then on, it should work like a charm.
Note:
This works only on the condition that the following line is in file /etc/sudoers:
%sudo ALL=NOPASSWD: ALL
(such line gives passwordless sudo privileges at group level, in this case to the sudo group)
(if this line is not present and you want to add it, make sure you use visudo)

Answer 8

Simply, in order to execute commands as root you must use su (even sudo uses su)
As long as you execute sudo ./script2.sh successfully just instead :
sudo su
"#" //commands as root here
"#" exit
//commands as use here
you can make it a shell function with the name sudo, but no other better way i think,however it's the case with scripts inti,rc android ..etc
must be tidy ;)
however this requires you to put NOPASSWD: su wich is totaly secure indeed
any way here just lacks POISX permissions principle which is filtering so dont enable something to all users or vice versa
simply, call sudo as much as you want with no additional thing then:
chown root script.sh
chmod 0755 script.sh
chgrp sudo script.sh
"make root owner of .sh"
"make it read only and exec for others"
"and put it in sudo group"
of course under sudo
that's it