id user1    (or) id -u user1

Association of UID / GID with Programs:

Whenever a user or group runs a program in Linux, they should have the permission to execute the program or else they are not allowed to execute the program. In order to make the program executable under this user account, the user need to set the Sticky bit which is called SUID (SetUserID) or SGID (SetGroupID).

Although this can be done by using Graphical User Interface, here we show you the way of how to achieve this in terminal which is very easy and faster.
Checking permission for files:

Step 1: To find ‘ What is existing permission for a file or directory ? ‘, supply this command in your terminal:

# ls -l

this command will display the permission for all the files in a directory.

Step 2: To find the permission for a specific file

# ls -l filename

replace the filename with the respective name of the file that you want to check.
The above commands specified will return something like ‘ drwxr-xr-x ‘. where,

d- directory.

r-read, w-write, x-executable.
If x is missing then it means, the file or program has not got the executable permission.
To Set Permission for files or Programs:

‘ chmod ‘ is the command used to achieve the task.

chmod changes the file mode bits of each given file according to mode, which can be either a symbolic representation of changes to make, or an octal number representing the bit pattern for the new mode bits.

chmod preserves a directory’s set-user-ID and set-group-ID bits unless you explicitly specify otherwise. You can set or clear the bits with symbolic modes like u+s and g-s, and you can set (but not clear) the bits with a numeric mode.

Step 1:

# chmod u+s filename

Note: Replace filename with the name of the file for which permission has to be set.
Here,

u – Associates of sets the user’s id as the owner of the file.

s – Sets the SUID; where g+s, sets the SGID.

Step 2: Now in order to check the changes we made, run the below command:

# ls -l filename

Step 3: Now you can run the program with desired and proper executable permission.
The chmod command has now changed the scenario, now after setting the permission for a program, the program will run with the Permissions that the user who runs the program have.

To know more about chmod command type: ‘ man chmod ‘ in your terminal.
Hence, you can check the permissions for the file and similarly you can disable permission for executing some files if you wish it lacks security.

From /var/www/vhosts/domain.com/statistics/logs/error_log :

[critical] [client 192.168.0.13] (13)Permission
denied: /var/www/vhosts/domain.com/httpdocs/.htaccess pcfg_openfile:
unable to check htaccess file, ensure it is readable

You will see Forbidden Error in your browser.

If you check the mentioned location you will notice that .htaccess file is probably not even there. Creating it and giving it the correct permissions won’t help of course.

In our case permissions set wrong on the httpdocs / httpsdocs directory itself.
Try this to fix:

cd /var/www/vhosts/domain.com/
chmod 755 httpdocs
chmod 755 httpsdocs

You don’t have to set the permissions to 755 as 751 for example will work as well. Play with the permissions on httpdocs to find the suitable solution.