Interview With the Author of "Mastering Cat"

Shlomi Fish writes "O'Reilly is publishing a new book titled 'Mastering cat,' about the UNIX 'cat' command. Here is an interview O'Reilly-Net conducted with the author about it. Read it to see if this book should be part of your bookshelf of technical books."

Comments

How about the followup?

[Fittysix]

?tac gniretsam

Re:How about the followup?

[Anonymous Coward]

I'd prefer the follow up "Mastering Pussy"

Re:How about the followup?

[lord_rob the only on]

rob@thinkpad:~$ pussy
bash: pussy: command not found

rob@thinkpad:~$ man pussy
No manual entry for pussy

Pussy doesn't even exist ...

Re:How about the followup?

[h4rm0ny]

Pussy doesn't even exist ...

That's strange. When I try:

h4rm0ny@mybox~$ grep -r pussy *

I get lots and lots of results.

Re:How about the followup?

[cayenne8]

Too bad there isn't a Unix command "Bater".....I'm sure that would be his next book.

:)

I think it would tend to be more of a self help book than a technical tome though...

Re:How about the followup?

[oldspewey]

No manual entry for pussy

I think I see the problem here - try starting her off with 3 or 4 vodka appletinis.

Re:How about the followup?

[Sir_Lewk]

'tac' is an actual *nix program, prints files out in reverse.

Re:How about the followup?

[palegray.net]

for getting [part of] a log file in reverse chronological order

Funny you should say that, it's exactly how I use the "tac" command.

Re:How about the followup?

[palegray.net]

pparadis@alpha:~$ vodka
bash: vodka: command not found
pparadis@alpha:~$ appletini
bash: appletini: command not found
pparadis@alpha:~$ tequila
bash: tequila: command not found
pparadis@alpha:~$ liquor
bash: liquor: command not found
pparadis@alpha:~$ beer
The program 'beer' is currently not installed.
You can install it by typing:
sudo apt-get install gerstensaft
bash: beer: command not found

Wow, I'm off to install beer on my laptop now.

Re:How about the followup?

[jonbryce]

pussy does exist, however there is no documentation for it, so you have to figure it out for yourself.

The other thing is, it isn't in $PATH, and slocate doesn't index it, so finding it is an exercise in itself.

I tried mastering cat.

[SuperBry]

But I kept on getting scratched...

Re:I tried mastering cat.

[ControversialMatt]

There's your problem. It's not your cat, you're his person.

Re:Frist Psot?

[snowraver1]

There is, but it only works if you are logged in as AC and if you post either a goatse pic, a long post about Obama's shit, or an instruction manual for someone of african decent.

Damn.

[castorvx]

I was hoping for a manual to help me read the icanhascheezburger comments.

Re:Damn.

[momerath2003]

That would be "lolcat," not cat. And here is a page to help you.

Master

[Hogwash McFly]

You can't master any cat, only dogs. As the saying goes - dogs have masters, cats have staff.

How hard is it to get CAT to work with HURD?

[TinBromide]

I've been trying to get my cat to play nice with gnu Hurd for a while. It seems like it starts to work, but then starts to ignore all IO and proceeds to SLEEP(3600). I am eagerly awaiting someone who can get a cat Hurd to work.

Re:How hard is it to get CAT to work with HURD?

[mrogers]

The trick to controlling a cat Hurd is pipes... lots of pipes.

O HAI

[Oxy the moron]

I CAN HAZ DIS BOOK NOW PLZ??

Re:O HAI

[Bob The Cowboy]

I CAN HAZ DIS BOOK NOW PLZ??
--

Proudly supporting the Libertarian Party.

I knew it... lolcats is a grassroots movement started by the Libertarians to... uhh... get... cheezeburgers?

I just /usr/bin/cat my coffee everywhere.

[Mr. Flibble]

I guess I forgot what day it was, but the title article made me spew my coffee in laughter.

As an aside, remember kids, don't do this:

cat foo | grep bar

It is bad Unix! (If you don't know why, read the non-existent book on cat...) ;)

Re:I just /usr/bin/cat my coffee everywhere.

[steveha]

As an aside, remember kids, don't do this:

cat foo | grep bar

It is bad Unix!

Eh, it's not that big a deal.

Yes, you can simply say "grep bar foo" and it will have the same effect with less typing. But it's really not that big a deal, and there are times when I would do this. Usually it is because I'm doing something like this:

shell_script foo | grep bar

And I'm not getting the results I expect; then I might swap out the shell script part for cat, to help me debug. It's easier to type

cat !*

or even

^shell_script^cat

than to retype the whole command.

As long as you know what you are doing, build the command line any way you like. The computer exists to serve you, not the other way around...

Now someone will mod me (-1, No Sense of Humor) or (-1, Beating the Joke Into the Ground). But I regret nothing! Nothing, I tell you.

steveha

Re:I just /usr/bin/cat my coffee everywhere.

[TheRaven64]

The correct general way of doing it (which works for all values of grep) is:

$ grep bar < foo

You don't need to do this with grep, since it can take a file as input, but in the general case, any time you are using cat with a single file and a pipe you should be using <.

It doesn't make much difference when you are running a single command, but it makes a huge difference when you are running a loop or something like a find command. The extra cat doubles the number of fork() and read() system calls, adds a load of unnecessary write()s and adds a lot of copying that is otherwise unneeded.

In the news today, a group of IT professionals ...

[Phizzle]

were found dead. Apparently they were playing a drinking game, and doing a shot for every lolcats reference on Slashdot.

Neuter to decrease aggression

[wonmon]

rm -r testes

Re:Neuter to decrease aggression

[kg9ov]

The cat probably won't be as open to that as you may think... I would suggest using the -f option as well, just to be sure.

Re:Neuter to decrease aggression

[upside]

How do you remove testes recursively? Are cat testes like Russian dolls? If so, is this somehow related to them having nine lives? Perhaps it makes sense. To kill a cat with any certainty you'd have to do something like

kill -9 $(ps axe | cut -d" " -f1 | tail -1 | head | cat)

which - as we know - is an arcane Unixish incantation to kill the cat by putting it in a bag and cutting somewhere between the tail and head with an axe nine times.

Or maybe you meant rm -f

P.S. I take no responsibility if you're stupid enough to run that command. Anything or nothing could happen.

Re:Neuter to decrease aggression

[Zashi]

Parent's command only works after you touch testes

Re:Neuter to decrease aggression

[wonmon]

Honestly, I used rm -r because I was thinking that ball1 and ball2 (and sometimes ball3) would be subdirectories, each containing millions of incomplete cat executables.

Re:Neuter to decrease aggression

[Anonymous Coward]

-f I can see, but -r?! What kind of cat to you have that you need to recurisvely remove testes? o.0

Re:Neuter to decrease aggression

[megaditto]

Inside the testes are smaller cats with smaller testes... In fact, it's the ever-shrinking copies of cats with testes all the way down.

Re:Frist Psot?

[Tim C]

No it isn't, and no, there really shouldn't...

Still Waiting

[Kushieda Minorin]

I'm still waiting for "Mastering true" and "Mastering false". The delay is understandable, considering nobody is able to harness the true power of these two commands.

I'm more intersted in tail than cat.

[Maxo-Texas]

If they released a book on how to master tail (heck, even find tail), it would change slashdot forever.

Re:I'm more intersted in tail than cat.

[drooling-dog]

That would be useful. And if there was one on mastering head, I'd buy it for the GF...

Re:I'm more intersted in tail than cat.

[Just Some Guy]

Alternatively, you could master head. I hear there's demand for it in certain log processing circles.

Re:I'm more intersted in tail than cat.

[fwice]

>---joke--->

   O
  \|/    <--- you
  / \

WHOOSH

Here goes:

[IceCreamGuy]

~# date
Wed Apr 1 13:31:50 EDT 2009
~# links2 -dump http://slashdot.org/ >> humortest.txt
~# cat humortest.txt | grep $somethingfunny
~#

Re:Here goes:

[morgan_greywolf]

You should really have RTFA. That's a UUOC. You just completely wasted a process call and unnecessarily wrote to a file:

links2 -dump http://slashdot.org/ | grep $somethingfunny

Of course, if we look at your use of an appending redirection (>>) (assuming humortest.txt already exists and has useful data), then you still unnecessarily wrote to a file:

links2 -dump http://slashdot.org/ | cat humortest.txt - | grep $somethingfunny

Re:Here goes:

[IceCreamGuy]

I know, I wrote that all out, and then I was like "wait, shit, I can just grep it right from the links2 output." So I wrote it on one line... but then I realized I wasn't using cat anymore and it ruined the joke. Please don't judge me!

P.S. thanks for introducing me to the phrase "UUOC," now I have something funny to read!

Re:Here goes:

[curunir]

You must not have gotten to the chapter entitled "Advanced Cat" (page 2). Cat can also be used as a target for piped output.

Try: ~# wget -o /dev/null -O - http://www.slashdot.org/ | cat | cat | cat | grep $somethingfunny
~#

Voila! No temp file needed. And all due to the power of cat (hint: the third one is the most important.)

Talk to the guys at

[wiredog]

EDS.

Re:I use...

[Tetsujin]

...Schroeder's cat. If it works, you don't know it, but if it doesn't you have to try again until you get it to work (if you can tell that it worked anyway). Then the pipe comes out to stop my mind frying.

That's "Schrodinger's cat". Your license to make quantum mechanics jokes is hereby revoked. To make sure you don't try to take your license back, we're going to keep you updated on its current velocity.

Re:I use...

[eXonyte]

Funny, I never realized that Schroeder had a cat...

Re:god

[bigstrat2003]

Protip: IGNORE IT.

Seriously, if you hate all these stories so much, leave /. for the day. It won't kill you. You know they're going to be here all day, so come back tomorrow. You'll be happier because you won't be reading the stories, and we'll be happier because you won't be bitching about our fun.

Upcoming second edition in 2012

[Tetsujin]

The second edition of "Mastering Cat" will include in-depth coverage of the use of "cat" in the new generation of object-oriented Unix shells. Key topics will include:

• "cat" type safety
• Using "cat" in traditional mode vs. object-oriented
• "cat" pitfalls: attempting to run "cat" on non-serializable live objects, "cat" on lists vs. "cat" on text files, using "cat" to capture user input (and dealing with the untyped data stream that results...)

You think I'm joking? Watch me. Hopefully what I come up with won't be quite the nightmare I'm trying to describe above. :D

But...

[cstdenis]

it's not even Caturday yet.

Re:Frist Psot?

[cayenne8]

"What is this "African Decent" you speak of? :)"

Well, it is like regular Descent, except rather than flying through caves, you are flying through a dry, arid desert area. And rather than lasers and smart bombs, you get a spear. If lucky, you get a power up weapon of a coke bottle that comes to you from the gods in the sky.

In case you were wondering what the book's like...

[Anonymous Coward]

here's a what a simple cat implementation looks like (The book leeaves additional features as an exercise to the reader):

HAI
CAN HAS STDIO?
I HAZ A VAR
MAEK ARGV[1] A TROOF, O RLY?
  YA RLY, VAR R ARGV[1]
  NO WAI, VAR R "STDIN"
OIC
PLZ OPEN FILE VAR?
  AWSUM THX
      IM IN YR FILE EATING UR LINES
    VISIBLE LINES
      IM OUTTA UR FILE
  KTHX
  O NOES
      INVISIBLE "ERROR!"
KTHXBYE

But seriously

[Sloppy]

For example, one case where I found that people truly underestimate the power of cat is in the prefixing a line example. You can do that with:
echo "This would be the first line" | cat - myfile.txt > myfile.txt.new mv -f myfile.txt.new myfile.txt
But people do not realize that and instead opted to use sed, awk, or even perl (!).

I've done that.

Wrong cover

[dlsmith]

O'Reilly would never put a picture of a cat on a book about "cat". It's way too obvious. (Well, nevermind.)

Re:Frist Psot?

[Scott Francis[Mecham]

Does the bottle need to be returned at the end of the game, though? Or is that a bonus mission?

Re:Frist Psot?

[fprintf]

Been there, done that. A few years ago I got first post and a +5 (w/o karma bonus) interesting. I don't see it listed on my achievements list, but I was pretty proud of it at the time. I think a few of the following comments even said that it was the first time they had seen such a beast, and this of course was when "first post" was an interesting challenge and something noteworthy to attain. Nowadays, meh!

Re:I use...

[Tetsujin]

That's "Schrodinger's cat". Your license to make quantum mechanics jokes is hereby revoked.

That's Schrödinger's cat. Your licence to use Latin characters outside the 7-bit ASCII range is hereby revoked.

Well, I don't have a license to use Latin characters outside the 7-bit ASCII range - which accounts for why I didn't. :D

But, still, touche. (D'oh! I did it again!)

obscurix

[sbeckstead]

I tried
schroedinger>mkdir /box
then
schroedinger>mv cat /box
Then when I went to look in /box
schroedinger>ls /box I found two files...
cat cat.dead
it's not in the manual...