Mounting UFS file systems in Ubuntu should be straight forward. Follow these simple steps to make sure that your are mounting your FreeNAS disks properly in Ubuntu:

Load the UFS module (or make sure its loaded)

sudo modprobe ufs

Make a directory where to mount the files on

mkdir ~/ufs_mount

To find out which device holds your UFS file system use the command fdisk -l, note which device you intend to mount.

Mount the file system to the directory your previously created

sudo mount -r -t ufs -o ufstype=ufs2 /dev/sdb1 /home/<your_username>/ufs_mount

(where: sdb1 is the UFS partition you want to mount and <your_username> is the your current username where the intended mounting point was created previously.

So you have recently shifted to Debian 10 and need a way for yourself, or someone else, to be able to execute authority-restricted operations on the system. These operations include information and privacy-sensitive tasks like changing the system configuration, performing user management, editing all files, installing/removing software, and upgrading your system and its components. As the first default user account after installation, ‘root’ is the most powerful user on Debian that can do all of the above. Although the name ‘root’ comes from this user’s access and permissions on the root directory, it is also termed as an Administrator, Supervisor and Super User.

So if root can do all, what is sudo and why do we need sudo users on our Debian?

What is Sudo?

Sudo or “superuser do” is a set of privileges that an Administrator/root can give to other users so that they can also perform some of the authority-restricted operations on Debian, while still maintaining the high-level security and authority on the system.

One way to give authority to users could simply be done by sharing the root password with them without getting into the whole sudo thing, but Linux has its reasons:

• Sudo gives temporary privileges to users that can be taken away any time by root. If we had shared our root password instead, it required changing it when the privileges were to be terminated.
• Working as root at all times is not a good security practice as one can mistakenly mess with sensitive system settings. So it is better to switch to sudo, and then back, when a restricted operation is complete.
• The commands performed as sudo are all logged, along with the username that executed them. This ensures accountability and auditing for all such users

In this article, we will explain how you can do the following on a Debian 10 Buster System:

1. Give sudo privilege to a user
2. Use sudo once it is granted
3. Remove sudo privilege from a user
4. Check which users have sudo privilege on the system

Note: Please note that only an authorized user can perform all these operations on Debian.

Giving Sudo Privilege To A User

Most Debian installations do not come with the sudo utility installed by default. Therefore, we will first install it on our Debian-as an Administrator. Open the Terminal application through the Application Launcher search bar and then log in as root through the following command:

$ su –

The system will ask you the password for root; providing which, you will be logged in as root.

Now, run the following commands in order to install sudo on your system:

# apt-get update
# apt-get install sudo

The sudo utility should now be installed on your Debian.

The /etc/sudoers file contains a list of users that have sudo privileges on the system. Although it is a text file, we do not recommend opening it in any of the available text editors. One small mistake can cost a user access to sudo rights forever.

Therefore, let us use the highly preferred and safe way of editing the sudoers file by running the following command: # visudo

This will open the sudoers file in a safe mode. Locate the section of the file that is marked in the following screenshot and then add the following line: %user       ALL=(ALL:ALL) ALL

I have added a user by the name of “sana” as a sudo user. Exit the file by hitting Ctrl+X. Then enter Y in order to save the modified file.

Now the user is marked as a sudo user and can perform many privileged operations on your Debian.

How To Use Sudo Once It Is Granted

Log in as a user that is granted sudo rights on Debian and then open the Terminal application. Let us now verify the sudo login and also if we are able to perform any of the authority-restricted operations.

If you enter the following command in order to install the VLC player, you will get the error displayed in the screenshot: $ apt-get install vlc

The reason here is that only an authorized user(root or sudo) is allowed to add and remove software on Debian. Therefore, we will run the same command as sudo now: $ sudo apt-get install vlc

As a sudo user runs this command, they will be asked to provide their own password.

After being verified as sudo, the installation process will begin- as shown above.

How To Remove Sudo Privilege From a User

The process of removing a user from the sudoers list is as simple as adding one. As root or as a sudo user, open the sudoers file as follows: # visudo

Or, $ sudo visudo

Then, remove or comment out the line which marks the user as sudo.

Save the file and the specified user is no longer recognized by the system as an authorized sudo user.

How To Check Which Users Have Sudo Privilege in The System

It is a good managerial check to see, from time to time, as to which users have been granted sudo rights on a system. It helps in deciding whose sudo status should retain and whose to let go. What we are looking for is a way to list the members of the ‘sudo’ group.

The following use of the Linux getent command will enable an Administrator to check which users have sudo privileges on your Debian: # getent group sudo

If you want to check whether a certain user is a member of the sudo group, you can make use of the Linux groups command as follows: # sudo groups [username]

After reading this article, not only will you be able to differentiate the terms sudo, root, Administrator, supervisor, etc, but also manage safely which ones you want to grant sudo rights to, on your Debian.

This article explains how to delete files older or newer than N days, with extra examples like matching only files using a particular extension, and more. For this we’ll use find, a command line tool to search for files in a directory.

You can delete all files and folders older than (with the file’s data modification time older than) N days from a directory by using:

find /directory/path/ -mindepth 1 -mtime +N -delete

An explanation of the whole command and what you need to replace:

• find is the Unix command line tool for finding files (and more)
• /directory/path/ is the directory path where to find (and delete) files. Replace it with the path of the directory from which you want to delete files and folders older than N days
• -mindepth 1 is used to not apply any tests or actions at levels less than the specified level. -mindepth 1 means the command should process all files except the command line arguments. Without using this, the command would attempt to also remove /directory/path/ if it matches the find criteria. You can skip it in all the commands mentioned in this article if you want to also match the specified find path. Also, there’s no need to specify this if you only look for files (-type f for regular files for example), and not folders
• -mtime +N is used match files that had their data (content) last modified N days ago. Replace N with a number (integer). In this command, files with a modification time older than N days will be deleted. It’s important to note that for example, if a file was last modified 1 day and 23 hours ago, -mtime +1 won’t match it, treating it as if the file was last modified 1 day, 0 hours, 0 minutes, and 0 seconds ago; see this explanation on why that’s the case, since the find man page doesn’t do this very well
• -delete deletes matched files and folders

How To Delete Files Older Or Newer Than N Days Using find (With Extra Examples)

 Logix  Updated on September 11, 2019console, how-to https://2333cfcb9c691179431d1ab1f195a4b8.safeframe.googlesyndication.com/safeframe/1-0-38/html/container.html This article explains how to delete files older or newer than N days, with extra examples like matching only files using a particular extension, and more. For this we’ll use find, a command line tool to search for files in a directory.

You can delete all files and folders older than (with the file’s data modification time older than) N days from a directory by using:

find /directory/path/ -mindepth 1 -mtime +N -delete

An explanation of the whole command and what you need to replace:

• find is the Unix command line tool for finding files (and more)
• /directory/path/ is the directory path where to find (and delete) files. Replace it with the path of the directory from which you want to delete files and folders older than N days
• -mindepth 1 is used to not apply any tests or actions at levels less than the specified level. -mindepth 1 means the command should process all files except the command line arguments. Without using this, the command would attempt to also remove /directory/path/ if it matches the find criteria. You can skip it in all the commands mentioned in this article if you want to also match the specified find path. Also, there’s no need to specify this if you only look for files (-type f for regular files for example), and not folders
• -mtime +N is used match files that had their data (content) last modified N days ago. Replace N with a number (integer). In this command, files with a modification time older than N days will be deleted. It’s important to note that for example, if a file was last modified 1 day and 23 hours ago, -mtime +1 won’t match it, treating it as if the file was last modified 1 day, 0 hours, 0 minutes, and 0 seconds ago; see this explanation on why that’s the case, since the find man page doesn’t do this very well
• -delete deletes matched files and folders

It’s important to note that -delete is a GNU extension, so it’s not available in all find implementations. For other ways of deleting files that works with all implementations, read the observations further down this article.

Want to test the command without removing any files or folders? Remove -delete and the command will list all files it finds matching your criteria, without deleting them:

find /directory/path/ -mindepth 1 -mtime +N

Let’s take a look at an example. To delete all files and folders older than 10 days from the ~/Downloads folder you can use:

find ~/Downloads -mindepth 1 -mtime +10 -delete

To delete all files and folders newer than (with a file modification time newer than) N days, use -N instead of +N:

find /directory/path/ -mindepth 1 -mtime -N -delete

Example in which we’ll remove all files and folders from ~/Downloads that had their contents modified between now and 10 days ago:

find ~/Downloads -mindepth 1 -mtime -10 -delete

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A few important observations that I recommend reading:

1. The arguments order matters! You should add -delete after matching the files. If it’s the first argument, every file (and folder) will be deleted from /directory/path/, regardless of them matching your query or not. So always add -delete at the end of the command.
2. Not all versions of find support -delete, which is a GNU extension. In case the find version you’re using doesn’t support -delete, you can use -exec rm -rf {} +, though there are find versions that don’t support this either from what I’ve read. Using -exec rm -rf {} + to remove files older than N days, and only matching files (keeping empty subdirectories):
3. What should work with any find version is exec rm {} \;. However, this performs worse than the other two solutions already mentioned, because it spawns an external process for each file it removes. This is why I left this solution for last. Use this to remove all files and folders older than X days from a directory:

Other examples of using find to delete files or folders based on their modification time

Only delete regular files older than N days, keeping empty subdirectories:

find /directory/path/ -mindepth 1 -type f -mtime +N -delete

Here we’ve used -type f to match only regular files. You can also use -type d to match folders, or -type l to match symbolic links.

Only delete files matching .extension older than N days from a directory and all its subdirectories:

find /directory/path/ -type f -mtime +N -name '*.extension' -delete

You can add -maxdepth 1 to prevent the command from going through subdirectories, and only delete files and 1st level depth only directories:

find /directory/path/ -mindepth 1 -maxdepth 1 -mtime +N -delete

You may also use -ctime +N, used to match (and delete in this example) files that had their status last changed N days ago (the file attributes/metadata AND/OR file content was modified), as opposed to -mtime, which only matches files based on when their content was last modified:

find /directory/path/ -mindepth 1 -ctime +N -delete

Create directory /var/backups

mkdir /var/backups

crontab -e

Add Database backup to the cron file:

#Backup Database (Before each day starts, backup Moodle prod DB from MySQL/MariaDB)
4 4 * * * root mysqldump dbname -u user -ppsaaword | gzip > /var/backups/moodle-db-`date +\%Y-\%m-\%d-\%H-\%M-\%S`.sql.gz

Add moodledata backup to the cron file:

4 10 * * * zip -r /var/backups/moodledata-`date +\%Y-\%m-\%d-\%H-\%M-\%S`.zip  /var/www/moodledata

Save 30 lasts backups

# Keep 30 SQL database backups and moodledata backups (last 30 backups of moodle)
 2 2 * * * find /var/backups/* -mtime +10 -exec rm {} \;