Question

In: Computer Science

Create a file and change the file permissions to (a) make it executable, (b) enable the...

Create a file and change the file permissions to (a) make it executable, (b) enable the SUID, and (c) use the ACL to add a permission for the root user.
Do a long listing of this file.

LINUX command line / virtual box.

Expert Solution

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(a) make it executable

To create a file in Linux , we can use the touch command.

Command:

touch file

In order to give executable permission , we use the chmod command followed by '-x' and the file name.

Command:

chmod +x file

(b) enable the SUID

chmod u+s file

u+s gives the SUID

ls -l command should show you whether SUID is applied or not. Simply look at the first field of ls -l output. The s in -rwsr-xr-x indicates SUID bit.

In some cases you will see a capital S instead of a small s that we saw above. Captal S indicates that there is no executable permission applied to that file/or script.

Command used:

chmod u+s file

ls -l file

(c) use the ACL to add a permission for the root user.

We need to run the setfacl command with below format to set ACL on the given file. We are going to give a rwx (read write execute) access to root user as asked in question on the created file named 'file'.

Command used:

setfacl -m u:root:rwx file

setfacl: Command
-m: modify the current ACL(s) of file(s)
u: Indicates a user
root: Name of the user
rwx: Permissions which you want to set
file: Name of the file

To check the default ACL values for a file or directory, use the getfacl command followed by /path to file or /path to folder.

If you have any doubts or any modifications, please comment and I'll help you out.

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venereology answered 2 years ago

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