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Asked: 2024-09-24T09:03:23+05:30 In:

How can I execute a shell script under a different user account that does not require a password on Ubuntu?

So, I’ve been trying to run a shell script on my Ubuntu machine, but I hit this wall when it comes to executing it under a different user account. Here’s the thing: I really want to automate some processes, but I can’t be bothered to enter a password each time, and I feel like there should be a way to do this without compromising security.

I know there’s this command called `su` that lets you switch users, but it always asks for a password. I’ve read a bit about `sudo` and setting up passwordless execution for specific commands, but I’m not entirely sure how to set that up in a way that allows me to run an entire script without entering a password.

Also, I’m a bit worried about security. I don’t want to end up in a situation where anyone can just execute my script as the other user, so I’m thinking there has to be a middle ground here. How do I make this work without opening the floodgates?

I’ve been looking into the `/etc/sudoers` file and saw there are configurations that let you specify which users can run which commands without a password prompt. But, I’m a little hesitant to dive into that because one wrong change could mess up everything!

I guess what I’m asking is: has anyone successfully set up a stable way to execute scripts as a different user without needing a password? What are the exact steps? Any tips on ensuring that it doesn’t create any security nightmares? I could really use some guidance here!

Thanks in advance for any help or examples, even if you’ve just played around with `sudo` and `su`. I’m eager to make this work but want to go about it the right way.

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    2 Answers



    1. Executing Shell Scripts as Another User Without Password

      Running Shell Scripts as Another User Without Entering a Password

      If you want to run a shell script as a different user without entering a password every time, you’re on the right track thinking about sudo. Here’s a simple guide to help you accomplish that while keeping security in check.

      Steps to Set Up Passwordless Execution

      1. Open the sudoers file: You need to edit the /etc/sudoers file. Use the command:
        2. sudo visudo

        This command is safer to use because it checks for syntax errors before saving.

      2. Add the User Rule: In the sudoers file, you can specify that a particular user can run a specific script as another user without a password. For example, if you want to allow the user username to run the script /path/to/your/script.sh as otheruser, you’d add the following line:
        3. username ALL=(otheruser) NOPASSWD: /path/to/your/script.sh
      3. Save and exit: After adding the line, save the file and exit the editor (for visudo, usually you press Ctrl + X, then Y, and Enter). This change allows username to run /path/to/your/script.sh as otheruser without being prompted for a password.
      4. Run the Script: You can now execute the script using:
        5. sudo -u otheruser /path/to/your/script.sh

      Keep Security in Mind

      While setting up passwordless sudo can be convenient, it’s important to limit the scope:

      • Only allow specific scripts that are necessary.
      • Avoid using NOPASSWD: ALL, as that can open up security issues.
      • Regularly review your /etc/sudoers file to ensure no unnecessary permissions are granted.

      By following these steps, you can automate your processes without being prompted for a password every time, while still keeping your system secure. Just remember to always proceed with caution when editing the sudoers file!



    2. To run a shell script as a different user without entering a password, you can use the `sudo` command along with editing the `/etc/sudoers` file. The first step is to determine which user you want to execute the script as, and then you’ll need to edit the `/etc/sudoers` file using the `visudo` command to avoid syntax errors. Add a line for your current user that specifies the script and permits it to run without a password. For example, if your user is `user1` and the script is located at `/path/to/script.sh` running as `user2`, add the following line: user1 ALL=(user2) NOPASSWD: /path/to/script.sh. Make sure that the script is owned by `user2` and has the correct permissions to be executed by that user.

      To ensure security and avoid potential vulnerabilities, limit the commands that can be run without a password. Be specific about the script or command and avoid using wildcards which might allow unintended commands to be executed. Additionally, consider placing your script in a directory that only the intended users can access. Regularly audit the `/etc/sudoers` file for any unnecessary privileges that could be opened up unintentionally. This way, you maintain control over who can run sensitive scripts without compromising the overall security of your system. Always test your configuration after making changes to validate everything works as expected.


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