Mostly you don't see a difference, unless you are using set -u:

/home/user1> var=""
/home/user1> echo $var

/home/user1> set -u
/home/user1> echo $var

/home/user1> unset var
/home/user1> echo $var
-bash: var: unbound variable

So really, it depends on how you are going to test the variable.

I will add that my preferred way of testing if it is set is:

[[ -n $var ]]  # True if the length of $var is non-zero

or

[[ -z $var ]]  # True if zero length

rrsync is designed to be used as a forced command for a particular key, so it should be exactly what you want.

A forced command is set up using the command option for a key in an authorized keys file and is then always run whenever this key is used for authentication, no matter what command the client requested. But it has access to the requested command so it can for example implement a validated, restricted version of it and that's what rrsync does.

You use it like this:

command="/path/to/rrsync -wo /allowed/directory/",restrict,from="a.b.c.d" ecdsa-sha2-nistp521 AAAAE...

Access for this key is limited to rsync to the /allowed/directory/ only. The -wo (write only) option means that rsync will be only allowed to send to the remote machine, -ro would only allow reading from the remote system, giving no option would allow transfer in both directions.

On the local side when you give arguments to rsync you must give the remote path relative to the allowed directory, so on A you would do eg.rsync -options /local/path root@B: and not rsync -options /local/path root@B:/allowed/directory/.

See also https://serverfault.com/a/915842/117645

Servers on exaroton don't have a fixed monthly price. You are only charged for the time you actually use your server.

To pay for services on exaroton, you use credits, each of which is worth €0.01. After creating your account, you get 5 credits for free to test our service. //

Running a server on exaroton costs 1 credit per GB of RAM per hour. For example, if you select 4 gigabytes of RAM for your server and run it for 1 hour, you would pay 4 credits. You can choose how much RAM (2 GB to 16 GB) you want to assign to your server on the Options page. //

To save credits, it is recommended only to run your server when somebody is playing on it. To achieve this, exaroton provides you with an AutoStop feature to automatically shut down your server when it has been empty for a while and an AutoStart feature to start your server automatically as soon as somebody tries to join.

Both features can be enabled for free on the Options page. We will only charge you for the time your server is actually running.

To go along with that recent CETP trial news, here's another one for the "We don't know much about human lipid handing" file. A dietary study originally done back in the 1960s and 1970s has been (almost literally) resurrected, with data pulled out of yellowing stacks of paper, old cardboard boxes, and ancient-format computer tapes.
What it shows is that, under about the most controlled conditions possible in a large human trial (institutionalized patients being served standard meals), that replacing saturated/animal fat in the diet with vegetable-derived fats and oils provided. . .no cardiovascular benefit whatsoever. In fact, the lower the cholesterol levels of the patients, the higher their death rates. This was in over 9,000 subjects over five years, probably the largest study of its kind ever conducted, and it had only produced one (not very thorough) paper in 1989 that didn't make much of an impression. ///

READ COMMENTS

McCullough says that it was Washington and his army that won the war for American independence. “He was not a brilliant strategist or tactician, not a gifted orator, not an intellectual. At several crucial moments he had shown marked indecisiveness. He had made serious mistakes in judgment. But experience had been his great teacher from boyhood, and in this his greatest test, he learned steadily from experience. Above all, Washington never forgot what was at stake and he never gave up.” Without Washington, there would be no America.

There are many things to celebrate during our nation’s semiquincentennial celebrations, and many men to honor for their part in our country’s birth: Thomas Jefferson, John Adams, Alexander Hamilton, Benjamin Franklin, and John Hancock among them. But no one looms larger than George Washington, who today seems almost mythical. At Washington’s funeral, Henry “Light-Horse Harry” Lee famously eulogized Washington as, “first in war, first in peace, and first in the hearts of his countrymen.” In 2026, it is our duty to ensure that honorific remains as true as when it was first spoken.

A pizza place near the Pentagon received an unusual rush in orders just an hour after the US launched its attack on Venezuela. //

That would be 3 a.m. in Caracas, one hour after the US rained down airstrikes on the capital city that lasted less than 30 minutes. //

The Pentagon Pizza theory follows pizza orders surrounding the Pentagon, speculating that an increase in late nights orders for federal agents corresponds with major historical events.

In the past 20 years, there have been only nine anthrax cases in the US.

However, B. anthracis is part of the larger Bacillus cereus group, which also includes B. cereus and B. tropicus, a newly recognized species. And these species can also carry and produce anthrax toxins. Both can be found in soils, and B. cereus is considered ubiquitous in the environment.

In 2022, CDC researchers found an unexpected pattern. Since 1997, there had been seven cases of infections from Bacillus group bacteria producing the anthrax toxin—all in metalworkers. Six of the seven were welders, hence the term “welder’s anthrax,” with the remaining case in a person working in a foundry grinding metal. Of the six cases where a specific Bacillus species was identified, B. tropicus was the culprit, including in the newly reported case.

Speculating risks
It’s unclear why metalworkers, and welders specifically, are uniquely vulnerable to this infection. In their 2022 report making the connection, CDC experts speculated that it may be a combination of having weakened immune responses in the lungs after inhaling toxic metal fumes and gases created during metalwork, and having increased exposure to the deadly germs in their workplaces. //

Environmental sampling of his workplace found anthrax-toxin-producing Bacillus in 28 of 254 spot samples. //

The experts also speculated that iron exposure could play a role. Bacillus bacteria need iron to live and thrive, and metalworkers can build up excess iron levels in their respiratory system during their work. Iron overload could create the perfect environment for bacterial infection. In the teen’s case, he was working with carbon steel and low-hydrogen carbon steel electrodes.

For now, the precise risk factors and why the healthy teen—and not anyone else in his workplace—fell ill remain unknown. CDC and state officials recommended changes to the workplace to protect metalworkers’ health, including better use of respirators, ventilation, and dust control.

23 hrs
volsano
One Y2K remediation I worked on had systems from the 1960s -- crucial systems that ran the whole show.

We easily (for some definitions of the word) fixed their 1980s and 1990s stuff that used 2-digit years.

But we did not touch the 1960s and 1970s stuff that had a specialised date storage format. It was 16-bit dates. 7 bits for year. 9 bits for day of year.

It was too assemblery, too unstructured, too ancient.

And, anyway, 9-bit year counting from 1900 (as they did) was good until the unimaginably far future.

The unimaginably far future is nearly with us: 1900 + 127 = 2027.

I am waiting for the phone to ring so I can apologise, - and quote them an unimaginably large number to finish the job.

After some time, the VAX crashed. It was on a service contract, and Digital was called. Laura Creighton was not called although she was on the short list of people who were supposed to be called in case of problem. The Digital Field Service engineer came in, removed the disk from the drive, figured it was then okay to remove the tape and make the drive writeable, and proceeded to put a scratch disk into the drive and run diagnostics which wrote to that drive.

Well, diagnostics for disk drives are designed to shake up the equipment. But monkey brains are not designed to handle the electrical signals they received. You can imagine the convulsions that resulted. Two of the monkeys were stunned, and three died. The Digital engineer needed to be calmed down; he was going to call the Humane Society. This became known as the Great Dead Monkey Project, and it leads of course to the aphorism I use as my motto: You should not conduct tests while valuable monkeys are connected, so "Always mount a scratch monkey."

Laura Creighton points out that although this is told as a gruesomely amusing story, three monkeys did lose their lives, and there are lessons to be learned in treatment of animals and risk management. Particularly, the sign on the disk drive should have explained why the drive should never have been enabled for write access.

In a separate opinion, justice Kenneth Lee accused California of misleading residents in smaller counties — where the open-carry ban does not apply — about how they can lawfully carry firearms. “Our constitutional rights,” Lee wrote, “should not hinge on a Where’s Waldo quiz,” The Hill reported.

The Big Apple firefighter’s union is steaming mad over the sudden discovery of 68 boxes of Ground Zero health data following the Sept. 11, 2001 terror attacks — files they were told never existed.

The recently surfaced boxes contain thousands of pages of information on possible toxins at the Lower Manhattan site that union members said could be used to add new ailments to the list of covered 9/11-related illnesses.

Some 343 FDNY firefighters lost their lives at the World Trade Center site on 9/11 with hundreds more having lost their lives since from health-related maladies.

“They should have used that evidence and those tests to prepare for the long term health care of the people that were down there,” Andrew Ansbro, president of the FDNY United Firefighters Association said at a press conference Monday. “The decision they made was to just hide it. //

The FDNY and advocates for other first-responders have been battling for years to get more data on possible toxins at the Lower Manhattan site, which has killed about 400 people since the attacks.

Any gas can be converted into a liquid by simple compression, unless its temperature is below critical. Therefore, the division of substances into liquids and gases is largely conditional. The substances that we are used to considering as gases simply have very low critical temperatures and therefore cannot be in a liquid state at temperatures close to room temperature. On the contrary, the substances we classify as liquids have high critical temperatures (see table in §
).

All gases that make up the air (except carbon dioxide) have low critical temperatures. Their liquefaction therefore requires deep cooling.

There are many types of machines for producing liquid gases, in particular liquid air.
In modern industrial plants, significant cooling and liquefaction of gases is achieved by expansion under thermal insulation conditions.

Rockall is an uninhabited – and uninhabitable – granite islet in the North Atlantic Ocean, covering 784 sqm and claimed by the United Kingdom, despite beings some 300 miles off the west coast of Scotland.

It is perhaps most well known, of course, for giving its name to one of the sea areas named in the British Met Office shipping forecasts.

Over the years, plenty of local Cinderella stamps have appeared for British islands with a dubious postal requirement and, in some cases – such as Stroma or Staffa – no population at all.

However, when we recently came across a stamp bearing the name of Rockall – a location once described as “no place more desolate, more despairing, more awful to see in the world” – we were suitably intrigued about who might be behind such a stamp, and why.

A charity expedition
It turns out that Rockall’s sole stamp issue to date related to a charity expedition to the island in 2005, under the name “Rockall Ho!”, where a team raising funds for Mental Health Media’s MEdia initiative successfully landed on the rock on 16 June and raised the flag of the “Peoples’ Republic of Rockall”.

In doing so, they joined the fewer than 20 people who are ever confirmed to have set foot there. //

Incidentally, the Latin used in the cancellation – “Ultra Mare Usque Nusquam” – translates as “Beyond the Sea Nowhere”. A fitting motto, perhaps, for this “awful” yet intriguing lump of rock in the Atlantic, and a place now immortalised in philatelic history thanks to its sole Cinderella stamp issue.

In philately, the abbreviation signifies a postage stamp that has never been hinged or mounted, retaining its original gum. Such a stamp is considered to be in perfect, unused condition, as issued by the postal authority. An example would be a stamp carefully preserved in pristine condition since its purchase.

Stamps in this superior condition are often more valuable to collectors, particularly for older or rarer issues. Maintaining original gum is a key factor in assessing a stamp’s quality and potential appreciation. Historically, hinging was a common practice, making unhinged examples from earlier periods relatively scarce and thus more desirable. This careful preservation contributes significantly to a collection’s overall worth and prestige.

Minecraft Bedrock Edition is the version of Minecraft that powers the iPhone / Android versions (formerly Minecraft Pocket Edition), the Xbox / PlayStation / Nintendo Switch editions and the free Windows 10 Minecraft edition.

Mojang has released a dedicated server which is considered to be in alpha testing.  I have found it to be very stable and able to run on a wide variety of hardware.

This script and guide are written to help you get a robust Minecraft Bedrock dedicated server up and running in only a few minutes!

This is the standalone version.

Sets up a Minecraft Bedrock dedicated server on Ubuntu / Debian with options for automatic updates, backups and running automatically at startup.
View installation instructions at: https://jamesachambers.com/minecraft-bedrock-edition-ubuntu-dedicated-server-guide/

Bedrock Dedicated Servers allow Minecraft players on Windows and Linux computers to set up their own server at home, or host their server using a cloud-based service.

Let’s take a look at how to setup a basic local Minecraft server both with and without mods.

Commands, also known as console commands and slash commands, are advanced features activated by typing certain strings of text.

There are two ways to make a Minecraft server allow list only. The first is through the chat box in-game, using the command "/allowlist on" (Bedrock edition) or "/whitelist on" (Java edition) and then "/allowlist add username" or "/whitelist add username" depending on which edition. The other way is to make a whitelist.json file at the root of your server, and add the username and UUID of a player to the file. //

This is one step that I forget far more often than I'd like to admit. Becoming an op on your server is crucial. With op powers, you can do just about anything in the Minecraft world.

To make yourself an op, simply type "/op username" in-game, or edit the ops.json file at the root of your Minecraft server.