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O comando tcopy
Colaboração: Rubens Queiroz de Almeida
Data de Publicação: 13 de Maio de 1997
Um comando bastante útil para manipulação de fitas ou mesmo
arquivos em disco, é o comando tcopy.
Quando utilizado da forma abaixo
% tcopy /dev/rmt0 /dev/rmt1
ele faz uma cópia de todo o conteúdo da fita contida na
unidade /dev/rmt0 para a fita na unidade /dev/rmt1.
Se invocado com apenas um argumento, como abaixo
% tcopy /dev/rmt0
file 1: record 1: size 10240
file 1: eof after 1 records: 10240 bytes
file 2: record 1: size 10240
file 2: eof after 1 records: 10240 bytes
file 3: record 1: size 10240
file 3: eof after 1 records: 10240 bytes
total length: 30720 bytes
Do relatório acima, pode-se ver que a fita contém três arquivos,
de tamanho 10240 bytes, contendo apenas um registro. No total
a fita possui gravados exatos 30720 bytes.
É especialmente recomendado o uso deste comando após a realização
de múltiplos backups em uma mesma fita, para se garantir que realmente
os múltiplos backups foram gravados em locais diferentes na fita
e não um em cima do outro, coisa que não acontece assim tão raramente ;-)
Ou seja, antes de fazer um upgrade baseado em backups que foram feitos
em uma mesma fita, confira se tudo deu realmente certo. E nunca é demais
fazer uma segunda cópia da fita.
A COMPARISON OF OPERATING SYSTEMS
All the passengers go out onto the runway, grab hold of the plane,
push it until it gets into the air, hop on, jump off when it hits the
ground again. Then they grab the plane again, push it back into the
air, hop on, et cetera.
The cashiers, flight attendants and pilots all look the same, feel
the same and act the same. When asked questions about the flight,
they reply that you don't want to know, don't need to know and would
you please return to your seat and watch the movie.
The terminal is very neat and clean, the attendants all
very attractive, the pilots very capable. The fleet of Learjets the
carrier operates is immense. Your jet takes off without a hitch, pushing
above the clouds, and at 20,000 feet it explodes without warning.
The terminal is almost empty, with only a few prospective passengers
milling about. The announcer says that their flight has just departed,
wishes them a good flight, though there are no planes on the runway.
Airline personnel walk around, apologizing profusely to customers in
hushed voices, pointing from time to time to the sleek, powerful jets
outside the terminal on the field. They tell each passenger how good
the real flight will be on these new jets and how much safer it will
be than Windows Airlines, but that they will have to wait a little
longer for the technicians to finish the flight systems. Maybe until
mid 1995. Maybe longer.
FLY WINDOWS NT
All the passengers carry their seats out onto the tarmac, placing the
chairs in the outline of a plane. They all sit down, flap their arms
and make jet swooshing sounds as if they are flying.
All passengers bring a piece of the airplane and a box of tools with
them to the airport. They gather on the tarmac, arguing constantly
about what kind of plane they want to build and how to put it
together. Eventually, the passengers split into groups and build
several different aircraft, but give them all the same name. Some
passengers actually reach their destinations. All passengers believe
they got there.
WINGS OF OS/400
The airline has bought ancient DC3s, arguably the best and safest
planes that ever flew, and painted "747" on their tails to make them
look as if they are fast. The flight attendants, of course, attend to
your every need, though the drinks cost $15 for an orange juice.
Stupid questions cost $230 per hour, unless you have Supportline,
which requires a first class ticket and membership in the frequent
flyer club. Then they cost $500, but your accounting department can
call it overhead.
The passengers all gather in the hangar, watching hundreds
of technicians check the flight systems on this immense, luxury aircraft.
This plane has at least 10 engines and seats over 1,000 passengers.
Bigger models in the fleet can have more engines than anyone can count
and fly even more passengers than there are on Earth. It is claimed to
cost less per passenger mile to operate these humongous planes than any
other aircraft ever built, unless you personally have to pay for the
ticket. All the passengers scramble aboard, as do the 200 technicians
needed to keep it from crashing. The pilot takes his place up in the
glass cockpit. He guns the engines, only to realize that the plane is too
big to get through the hangar doors.