I have a custom requirement by a specific user , that he wants me to write a shell script to move files from one folder to another folder . These two folders have different owners
Now, I managed to do that by logging in as root, but want to achieve this without giving root privileges to user.
I am not allowed to do any new package installation,
Not allowed to use any another shell than Korn .
Please suggest a solution.
Yeah I know this is not a safer way and a bad approach, still am curious about satisfying the need of a user ..
Write a script to move files.
change the ownership of the script to root
Update the /etc/sudoers file to give the user permissions to run the script as root:
user ALL = NOPASSWD: /opt/script.sh
User can execute the script: sudo /opt/script.sh
That shouldn't ask for root password, but give the user privileges to run the script as root.
Related
My problem is about using the source command for everyone logged in.
Let's say I have a file with the content:
#!/bin/bash
alias ha='echo test'
Now if I source it and write ha, I'd get the message test.
Now what if there's someone else logged in, and I want it to be sourced for his account? Can you write something like source (username) (filename)?
Provided that other uses have read permission to your script, and read permissions to its directory and parent directories, they can source that file. Assuming your user name is "thesourcequestion", and you are keeping the alias file (let's call it alias ) in your home directory, other users can source it with the following command:
source ~thesourcequestion/alias
Or just (same thing):
. ~thesourcequestion/alias
Incidentally, some shells only accept the source keyword (like c-shell IIRC).
If you are the admin of the box, consider the solution presented here:
https://askubuntu.com/questions/610052/how-can-i-preset-aliases-for-all-users/986053
In short, there are system files that can be modified that will create the alias for users. The alias will be available to them next time they login.
Don't overlook the part of my answer about providing permissions to your file. For example, you can give read permissions to the file this way:
chmod a+r ~thesourcequestion/alias
The above syntax adds (+) the read attribute (r) to all (a).
My question is how I can make one folder accessible when script running.
In this case lets call there is bob who copying his folder by using script to specific location and there is jeff who also sharing the same group as bob also he copying his file to there with using script.
The problem is that when I set file group they need write and execute permission and when I gave to them they are able to see each other file content if they know full path of the file.
To stop that I am thinking to completely deleting all permission on folder and only giving the permission when script running and doing copying process.
But problem is that when those users run the script and script try to chmod the file permission they are not going to be able to because they don't have enough permission to do it. Also if I add them on sudoers, they are going to be able to chmod and change anything as they want to change.
So I am so confused about how I can make the script change permission of folder and when copying completed turn back to previous permission
You should add a sudoers entry to allow ALL or the selected group to run a given script that does the copy to a restricted directory, with NOPASSWD to avoid the password prompt.
Then the users invoke
$ sudo /path/to/copy-to-restricted-dir files*
but users don't have access to restricted directory nor to chmod.
I created this simple script to allow the user to remove files created by the web server in his home directory without giving him "su". Both scripts are set with "chmod 4750".
The craziest thing is that they DID work and now they don't. Here's the scripts:
#!/bin/bash
# Ask for directory to delete
echo "Enter the file or directory you would like to delete, the assumed path is /home/user"
read DIRECTORY
rm -rf /home/user/"$DIRECTORY"
echo "Deleting /home/user/$DIRECTORY ..."
exit 0
2:
#!/bin/bash
# Reset permissions
echo "Resetting the ownership of the contents of /home/user to user."
chown -R user /home/user
exit 0
I will make them a little more advanced and work for multiple users but right now I cannot even get the simple version to work. It works when run as root of course. It used to work when run as user 'user' but now it doesn't. I get this:
user#dev:/home/user$ delete.sh
Enter the file or directory you would like to delete, the assumed path is /home/user/[your input]
test-dir
rm: cannot remove ‘/home/user/test-dir/test-file’: Permission denied
Deleting /home/user/test-dir ...
and
chown: changing ownership of ‘/home/user/test-dir’: Operation not permitted
What can possibly be the problem?
-rwsr-x--- 1 root user 291 Nov 6 05:23 delete.sh
-rwsr-x--- 1 root user 177 Nov 6 05:45 perms.sh
There is a pretty comprehansive answer at https://unix.stackexchange.com/questions/364/allow-setuid-on-shell-scripts
Bottom line is that there are two main points against it:
A race condition between when the Kernel opens the file to find which interpreter it should execute and when the interpreter opens the file to read the script.
Shell scripts which execute many external programs without proper checks can be fooled into executing the wrong program (e.g. using malicious PATH), or expand variables in a broken way (e.g. having white space in variable values), and generally it has less control on how well the external programs it executes handle the input.
Historically, there was a famous bug in the original Bourne shell (at least on 4.2BSD, which is where I saw this in action) which allowed anyone to get interactive root shell by creating a symlink called -i to a suid shell script. That's possibly the original trigger for this being prohibited.
EDIT: To answer "How do I fix it" - configure sudo to allow users to execute only these scripts as user root, and perhaps use a trick like in https://stackoverflow.com/a/4598126/164137 to find the original user's name and force operation on their own home directory, instead of letting them pass in any arbitrary input (i.e. in their current state, nothing in the scripts you include in your question prevents user1 from executing the scripts and passing them users2's directory, or any directory for that matter)
I have a unix shell script file whose owner is "xyz" when run deletes some specific files.
I want to trigger this script to delete files in some other directory where the owner for the files to be deleted is different from the owner of the script. Is this possible? Is this possible to run this script as different user so that it can delete those new files?
EDIT : I use Autosys to periodically trigger this script.
You can chmod the files that need to be deleted first if you have sufficient rights. Afterwards your script, no matter what user it executes, will succeed.
Examples : http://en.wikipedia.org/wiki/Chmod
Usually you use sudo for that:
sudo -u ANOTHER_USER /path/to/the/script.sh
However, your current account needs proper permissions to do so. You can configure those permissions using the file /etc/sudoers.
You'll find a ton of articles out there how to use sudo. This for example: http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:Ch09:_Linux_Users_and_Sudo
I have made a script for installing a control panel.
I've uploaded the script to a server so people can wget it to their machines.
The only issue is that you have to chmod it after download. Is there a way to remove this step? How would I go about keeping 755 perms on the downloaded script?
When a user downloads the file, the file will automatically get some default permission. In UNIX, each user will have a default set of permissions which apply to all files created by that user, unless you explicitly set it to something else.
This default is called the umask, after the command used to change it. It is either inherited from the login process, or set in the .shrc or .login file which configures an individual account, or it can be run manually.
Typically the default configuration is equivalent to typing 'umask 22' which produces permissions of:
-rw-r--r-- for regular files, or
drwxr-xr-x for directories.
In other words, user has full access, everyone else (group and other) has read access to files, lookup access to directories. As you see above, the execution access is not default for files.
Hence you need to explicitly change it.