Caracteres invisíveis
Colaboração: Rubens Queiroz de Almeida
Data de Publicação: 27 de Junho de 1997
Tomemos a seguinte seqüência de comandos:
% touch a a
% ls
a a
Temos no diretório, aparentemente, dois arquivos com o mesmo nome.
O carácter <CTRL>-X não aparece na listagem, está invisível
Mas como isto é possível? Neste caso é evidente que os dois arquivos
não possuem o mesmo nome; um deles chama-se "a" e o outro
chama-se <CTRL>-Xa. Mas como fazer para identificar o problema?
O comando cat pode ser usado para isto:
% ls | cat -v
^Xa
a
A opção -v faz com que o comando cat exiba também os caracteres
invisíveis.
Outra dica, às vezes a listagem de um diretório pode parecer um
pouco estranha, como em:
% ls
a a
Porque a listagem não começa na primeira coluna? Vejamos porque:
% ls | cat -v
^A
^X
^Xa
a
Existem dois arquivos "invisíveis", ou seja, os seus nomes são compostos
de caracteres não exibíveis (existe esta palavra?), no caso ^A e ^Xa.
Da mesma forma que o comando "cat -v" foi utilizado neste caso, para
listar diretórios, ele pode ser usado para listar aqueles arquivos
onde tudo supostamente deveria estar funcionando mas não está.
Neste caso o culpado pode ser um destes caracteres invisíveis em
um local onde não deveria estar.
Fit the Twenty-fourth: Last Bastard Operator, vignette #2
BOFH © 1990-1995 by Simon Travaglia and Datamation. All rights reserved.
Bastard Operator From
Updated: Tuesday 14 November 1995
It's a stinking hot day in my non-air conditioned office and I'm annoyed.
The sort of annoyed that's described, mistakenly, as red hot. The correct
colour choice, is, of course white.
I login to my account and there's three helpdesk mail requests, all ticking
away to expiration, then escalation, then further escalation, then followup
mail message, then even further escalation, then 2nd followup mail message
and casual phone call, then still further escalation, then non-casual phone
call, then threats, then, ultimately, and sadly, violence. But not so sadly
that I won't resort to it. And they know I will too...
Because I used to be...
T H E B A S T A R D O P E R A T O R F R O M H E L L ! ! !
...and sometimes, late at night I get these twitches. Like dead people get.
(Or, as I prefer to call them, perfect computer users)
In the mornings I get them too. Like when the phone rings. And when I get
email. And when people talk to me. AND when people are hogging the expresso
machine to make fluffy milk. But apart from that I'm cured. A new man.
I smile at the thought and look, in reminiscence, at some reminders of my
past. A couple of backup 8mm tapes with cartoons on them. The thank-you
cards for my attendance at 23 seperate funerals of computer center staff.
The mains plug with the thinwire ethernet plug at the end. I didn't ever get
round to trying that one either, so I don't even know what it would've done.
I'm bored.
That's it alright. I am *absolutely*, *stinking*, *UNCONTROLLABLY* bored. I
get up and slip a fingerprint free magnet on top of the reed switch that the
Boss had installed in my display cabinet while I was on holiday, then pry
the glass door open with a screwdriver. As far as I can figure, the switch
is supposed to ring an alarm if the door is opened.
If I've said it once, I've said it a thousand times - "Inexpensive means
Inefficient".
I open the door to the clamour of... silence. Well, silence and John Lee
Hooker's "Mr Lucky" from my CD. I grab my aforementioned etherkiller and
wander down the hallway to the switchboard, applying another magnet and
opening that to silence as well.
That's what's missing in society today - trust.
I pull the 15 amp breaker for the meeting room, then wander on round and
plug the etherkiller into a cheap 24hour timer set to 5 minutes from now. On
the way back to the the switchboard I hear the first few murmurs about
excessive collisions. I plug in my unpatented nail "fuse" (estimated fault
current 200-300 amps) with a set of heavily insulated pliers and wander off
to the tea-room to start my expresso brew. Halfway through the make, the
machine stops. Now *THAT'S* what I call a collision.
I look around in a bewildered manner as panic erupts on all sides, half-made
expresso in my hand. I step out into the hallway and behold pandemonium. Two
programmers are fighting over a CO2 fire extinguisher in an effort to put
their terminals out. I wander down to my room just as my X terminal, the
unreliable peice of excretia it is, flames it's last and lapses into a dull
smoulder.
"My cabinet!" I cry in 'horror' and hear the extinguisher struggle end
abruptly. In a flash the two programmers concerned are behind me staring
into my room. Shortly thereafter the boss runs up as well.
"What's this magnet for?" I ask, picking it up and hearing a bell start
chiming in the distance.
"You bastard!" one of the programmers utters
"I'm sorry?" I ask, turning.
"YOU did it didn't you?"
"What? Break into my own cabinet? But I've got a key.."
That's the terrible burden of proof really - in this day and age, you need
some to make an accusation.
The late-breaking news comes in that one of the consultants had a set of
head- phones plugged into a CDROM drive hanging off their networked PC. But
not anymore. Now there's an unexpected vacany in the department. I blame the
Ethernet Isolation specs. 3KV my backside!
Quicker than you can say "Help us with our enquiries" I'm "helping the
police with their enquiries".
"What is this, can you tell me?" a burly officer asks, right up in my face.
He holds up a magnet.
"It's a magnet. There was one on my cabinet!" I cry
"Yes. And where did you get them?" he asks, seizing control..
..and losing it. "On my cabinet! I just said!"
"No not this one. The others. Where did you get them?"
"Others? What others? You mean there were more on my cabinet! Why?!?" (I can
play the "stupid game" forever, having had years of education at the hands
of computer lusers.) He tries a different tack.
"What would you say this was off?" he asks
"My cabinet! It was on my cabinet, I told you! I pulled it off... and I
think I heard a bell ringing"...
.... .. .
A couple of hours later I'm back at my desk with Mr Lucky, no charges
pressed. I close my cabinet, satisfaction mine for the first time in a long
while.
Then the phone rings...