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Unix Operating Systems Software

Learn How UNIX Multitasks 160

BlueVoodoo writes "On UNIX systems, each system and end-user task is contained within a process. Learn how to control processes and use a number of commands to peer into your system."
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Learn How UNIX Multitasks

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  • exciting (Score:5, Funny)

    by Anonymous Coward on Monday April 09, 2007 @10:54AM (#18663973)
    Wow! ps, top, sleep, kill, PIDs? This is some pretty groundbreaking stuff here!
    • Re:exciting (Score:5, Interesting)

      by Anonymous Coward on Monday April 09, 2007 @11:03AM (#18664117)
      Don't forget to set the I_WANT_A_BROKEN_PS [rt.com] environment variable!
    • by Anonymous Coward

      specialized tools, such as top, ps, and kill, all are readily available.

      Specialized tools? Everybody uses these all the time, and I note he didn't mention nice or renice - the ones nobody ever uses. This is not intermediate level stuff, this is beginner stuff. Awk, M4 and sed are intermediate - and they aren't specialized tools either.

      • Everybody uses these all the time, and I note he didn't mention nice or renice - the ones nobody ever uses.
        So not true, lots of folks re-nice the spamassassin daemon to keep it from chewing up resources. Though, I do agree that they deserve a mention even though the article seems to be targeted at beginners. To be fair, the Slashdot title was a bit misleading - even compared to the summary.
    • FTFA:

      "If it helps, you can think of a process as its own sovereign nation, with borders, resources, and gross domestic product."

      Sounds like he is trying to teach UNIX to a bunch of Economics majors.
    • Re: (Score:2, Funny)

      by PPH ( 736903 )
      Now, that wasn't very nice.
    • Re:exciting (Score:5, Funny)

      by morgan_greywolf ( 835522 ) * on Monday April 09, 2007 @12:05PM (#18664983) Homepage Journal
      I especially liked this one:

      $ ls -l /usr/bin/top
      -r-xr-sr-x 1 root tty 19388 Mar 20 2005 /usr/bin/wall

      Wow. That's a neat trick.
  • Woop-tee-doo. (Score:1, Insightful)

    by McDutchie ( 151611 )
    It's a basic primer on UNIX job control. Whee. Not that it isn't well done or useful to the target audience -- but how is this 'news', never mind 'stuff that matters'?
    • Re: (Score:3, Insightful)

      by billcopc ( 196330 )
      It's called "here's a slashdotting to boost my pagerank". Whenever you see useless tripe on the internet, chances are it's designed to generate idiot traffic and/or ad revenue. Thank Google for this glut.
    • but how is this 'news', never mind 'stuff that matters'?
      It matters to us *nix developers with a conscience. Just remember fellas, this [imageshack.us] is what happens to all spawned PIDs in a chroot jail. Please, think of the children. And, there really is a spoon!
      • Re: (Score:1, Informative)

        by Anonymous Coward
        You should have said NSFW. It really doesn't matter for me but if someone at work has a IT dude with nothing better to do looking at log files for the heck of it that person could get into trouble ;-). Course if hes reading slashdot he or she is already in trouble already lol
        • My apologies. Sometimes I forget even my own standards when in the cartoon realm. It's a fork and a spoon making snu snu for those at work.
    • Re:Woop-tee-doo. (Score:5, Insightful)

      by ukemike ( 956477 ) on Monday April 09, 2007 @01:31PM (#18666185) Homepage

      It's a basic primer on UNIX job control. Whee. Not that it isn't well done or useful to the target audience -- but how is this 'news', never mind 'stuff that matters'?

      "Looks like someone has a case of the mondays!"

      I thought that the slashdot community was supportive of people migrating away from windoze to the linux world. TFA covers things that are not obvious to people that don't have *nix experience. It was a nicely written article. It might spur discussion on further basic knowledge needed to deal with linux. The whole community of "nerds" includes slide-rules to slashdot. Not every nerd is a sysadmin. To me this was useful. I already had learned 75% but had forgotten some and a bit was new and might be handy. That is "stuff that matters" to me. If nothing else cranky sysadmins, when posed with a question about something this basic, could roll their eyes condescendingly and give a link to this handy page.

      The better question is why is this posted under "devcelopers"?
      • Re: (Score:1, Flamebait)

        I thought that the slashdot community was supportive of people migrating away from windoze to the linux world.

        We are supportive of people migrating away from windows. The slashdot community has done a lot to spread ubuntu. But none of that makes TFA news. This is 'stuff that matters', but I think if you've gotten to the point where TFA's content is helpful, you will already know how to find that information. When I want to have a lively discussion about a "dead-horse" historical issue, even one related to the design of my computer's OS, I will seek it out. Elsewhere.

        If this topic had been brought up as an "ask sla

      • I thought that the slashdot community was supportive of people migrating away from windoze to the linux world. TFA covers things that are not obvious to people that don't have *nix experience.

        It also covers things that people simply don't need to know. Start up Ubuntu (or whatever) and run the system monitor, just like in Windows, to kill processes. That's about all you need to know!

        Unless someone is a hardcore tech geek on Windows (snicker) they aren't going to need to know anything like this to move fro

      • "Looks like someone has a case of the mondays!"
        Could you send me your name, address, floorplan, daily schedule, and also mail me a copy of your housekey, please? I once swore to kill anyone who ever actually said that. Especially if they said it at a time when I actually did have a "case" of the "mondays". \end{tonguecheek*}
  • Next... (Score:5, Funny)

    by ari_j ( 90255 ) on Monday April 09, 2007 @10:55AM (#18663989)
    Learn how UNIX stores files. This revolutionary new article will show you how to use ls and cd, and you will walk away with a complete understanding of how files are stored. More magic demystified, indeed!
    • What? No 'touch'? I take it that's the polictially correct article?
      • Re: (Score:2, Funny)

        by drinkypoo ( 153816 )
        We had to eliminate that command because it was giving pedophiles ideas. From now on, touch will be replaced with echo redirected into a file. Just redirect nothing onto the end of a file to update the mtime... Won't someone think of the children?
  • by Anonymous Coward
    alias renice 'echo Renice\? You must mean kill -9.; kill -9 \!*'
  • Ok, I knew /. was getting less and less computer literate.

    But if you don't fucking know basic UNIX process control, don't talk about computers, or IT, k?

    Seriously, this isnt even Computers 101. This is the bullshit you're expected to know to take Computers 101.

    • Sadly though, there are probably people graduating from "computer science" programs who only know of 'processes' as something you get after pressing Ctrl-Alt-Del and clicking on the "Task Manager" button.

      You're vastly overestimating the CS curriculum, at least at my local State uni, if you think that UNIX anything is taught in the 100-level courses.
      • Re: (Score:2, Insightful)

        by chrism238 ( 657741 )
        That may all be true, but you don't graduate with just the 100-level courses!
        • When all the upper level courses are taught in Java, it really becomes a moot point. At my university, all the non-java classes are at the 100 and 200 level.
      • by loconet ( 415875 ) on Monday April 09, 2007 @01:10PM (#18665855) Homepage
        I think one of the big problems is not so much the lack of content offered in the classroom. The bigger problem I see IMHO is the lack of interest from students as a result of a poor introduction into what UNIX really is and how it will come to play in their careers (ie: beyond their gaming desktop).

        I have recently gone back to school to finish up my CS degree after having worked in the industry for several years and I'm surprised at the ignorance of UNIX/Linux's usefulness from people who have already taken a UNIX/Linux course in my school. It seems profs are jumping straight into bash scripting without properly introducing what UNIX really is, what the difference between UNIX and Linux is, how it is used today, why it is important to learn it, how it is different than Windows, the philosophy behind UNIX, how it is useful as a tool, etc. All students are being exposed to is a command line and some scripting. No context in the technology whatsoever. It is then not surprising that students come out of those courses thinking UNIX and Linux are useless since Windows/Macs do it better, easier. This results in them erasing whatever little knowledge they acquired as soon as exams are done with.
    • by NeoPaladin394 ( 1044484 ) on Monday April 09, 2007 @11:27AM (#18664455)
      This is an article in a series (labeled Introductory to Intermediate) designed to introduce to the O/S. The first article in the series [ibm.com] talks about how to use find! You can't point at an O'Reilly book and call Stupid because you know what it talks about. The article is well written and explains processes perfectly for the intended audience, and not everyone is born with the intrinsic knowledge of how every O/S in the world works. Readers on this site want a world of O/S choices, but are so willing to bash an article that will help accomplish just that? And just because it gives a quick, sentence overview of PS and LS? Unbelievable.

      The article may or may not belong on the front page, but claiming someone's illiterate for not knowing stuff like this, especially if they were in an Apple or MS shop? Heaven forbid.

      • The article may or may not belong on the front page, but claiming someone's illiterate for not knowing stuff like this, especially if they were in an Apple or MS shop? Heaven forbid

        Um, I don't care if they are in a DOS/Novell shop. This is basic stuff and are also concepts that have relevance in all OSes.

        As for Apple or MS shop? Ok, Apple uses a BSD interface to a Mach kernel and is very much a *nix architecture. In the MS Shop, NT also includes a full BSD subsystem that is used for running *nix applicait
        • If anyone hires someone that doesn't understand basic 'computing principles', they are hiring computer 'illiterate' techs. PERIOD.

          I was referring to the specific O/S implementation details outlined in the article, not the basic freshman year, "What is a process?" My fault for not being more specific in the closer, but I still stand by my statement.

          If you hire someone who is supposed to be working with Windows/*NIX interoperability and hadn't a clue how UNIX works, then you have a problem and, yes, the new g
          • Re: (Score:3, Interesting)

            Ok, agree with one exception.

            If you hire someone who is supposed to be working with Windows/*NIX interoperability and hadn't a clue how UNIX works, then you have a problem and, yes, the new guy is illiterate for the task he is given. If you hire a developer to make a .NET application for a specific Windows architecture, then I wouldn't consider the user illiterate for not knowing the processes and binary code Unix launches on startup. At least, not in the incompetent sense that the word is being used here.


            I

            • and when parts of the project were moved to Linux servers, the person literally did not understand why upper & lower case mixed reference tags were failing. And as scary as that sounds it very common.


              Scary? Not really. One platform has different quirks than another. The linux world is by and large case sensitive, so people have learned to instinctively think about case. The Windows world isn't, so people are less inclined to think about case. It only takes about a minute to explain the case sensiti
              • The Windows world isn't, so people are less inclined to think about case. It only takes about a minute to explain the case sensitive issue.


                The irony is that the programmer was using a freaking case sensitive language, and still didn't get it the first time it was explained to him.

                This is part of the basic understanding I was talking about. If someone can't think outside a box enough to go, "Hmm mayber the OS FS is case sensitive," then they can't be fixed.
      • I agree that the article is beneath intermediate and advanced users of *nix .

        As a noob, *nix illiterate, etc., I appreciated the article. I've had some past experience on a *nix box. I know very little. Of course, I didn't know a whole lot of JCL before I started working with mainframes either. I wouldn't expect anyone not familiar with a mainframe to immediately know the error codes produced by the system or what an initiator is either.

        Like a previous posted has pointed out, due to the slashdot communi
  • by Anonymous Coward on Monday April 09, 2007 @10:58AM (#18664037)
    I get
    "ps: Command not found"

    What do to? Heeeeeelp.
  • Incredible! (Score:5, Funny)

    by Wuhao ( 471511 ) * on Monday April 09, 2007 @11:00AM (#18664049)
    With several businesses now owning their own Unix mainframes, and with some futurists speculating that hobbyists may one day have full-fledged Unix systems in their basements, a detailed understanding of Unix operation -- including its intricacies, like these "processes" -- becomes increasingly important, even for people not charged with the operation of one of these computational goliaths. I for one plan to study these "processes" carefully.
    • by PPH ( 736903 )
      I must be behind the times. All I have is half a dozen or so PCs and laptops running something called Linux. Not a mainframe in sight. And I don't even have a basment to keep them in!
  • An in-depth look at Linux filesystems. Specifically, how to make use of the mysterious "ls" command.
    • For a lot of modern desktop Linux users, who think that KDE or Gnome are the 'standard unix interface,' an article on ls would probably be quite eyeopening, not to mention incomprehensible.

  • Use the Firehose! (Score:5, Insightful)

    by 644bd346996 ( 1012333 ) on Monday April 09, 2007 @11:03AM (#18664113)
    If you think this article is stupid and an insult to your technical prowess, go to the firehose and vote it down.
    • by gEvil (beta) ( 945888 ) on Monday April 09, 2007 @11:09AM (#18664193)
      Mod Parent Up! Vote Article Down!
    • Hey, there are editors that (hopefully) get money to do something.
      Maybe they should start?
    • Re:Use the Firehose! (Score:4, Interesting)

      by jellomizer ( 103300 ) * on Monday April 09, 2007 @11:57AM (#18664911)
      Yea you are a big man now. You read an article and you understood it before you read the article. So you feel inclined to instult the fact that some people may not know this.
      Yes this is Basic Unix Command Line suff. But a lot of Unix users don't go beyond typing the command to run the program. Forking, Piping, Scripting, is more then what they really use. An some of the times these people who don't understand this are actually smarter then most of us. Say a Physicist who uses Unix to test their math or run complex simulations. Also there are a lot of people using Linux/Unix who were never formally taught how to use it. So they stick in the GUI, or Find and install programs that a simple small script can acomplish. I know you want to do your "I am an Alpha Geek" while thumping your chest. But if an article gets posted and you really don't care, then don't read it and move along. Because getting an article on information that you already know isn't a big deal, this is far more mature then say the latest Cool PC Mods.
      • by Fezmid ( 774255 )
        Yeah, but should we really have basic articles like that on this site? Maybe we should have an algebra primer? 2x+4=12, show me how to solve for x. Or using your physicist example, should we have an article describing the coefficient of friction for us? No, because it doesn't really fit with the site.

        Nobody's saying that the article isn't useful, but it's not a /. article.
      • by Gilmoure ( 18428 )
        Alpha Geek Chest Beater is right. Slashdot is not the place for articles on how to use an OS (even if most people here already know this). Slashdot's about how expensive new Apple gear is and Windows bashing. Get with the program!
    • by Vellmont ( 569020 ) on Monday April 09, 2007 @12:14PM (#18665097) Homepage

      If you think this article is stupid and an insult to your technical prowess, go to the firehose and vote it down.

      Not everyone on Slashdot is at the same level as everyone else. While I've known all the stuff in the article for 10-12 years, I'm certain there's a significant number of people here that have no idea about process forking, or what the init process is.
      • by clintp ( 5169 )
        And for a better introduction to process creation, I offer:

        Mr. Peabody Explains fork() [peccat.us]
      • Re: (Score:1, Interesting)

        by Anonymous Coward
        I sent it to two teams I work with. I had recently made a presentation that explains some similar things, and this comes at it from a different angle. I think it was very useful.

        (Myself, I know it all, but not everyone does)

      • If you think this article is stupid and an insult to your technical prowess, go to the firehose and vote it down.

        Not everyone on Slashdot is at the same level as everyone else. While I've known all the stuff in the article for 10-12 years, I'm certain there's a significant number of people here that have no idea about process forking, or what the init process is.

        Thank you.

        I primarily work on Windows-based systems having only touched on *nix-based systems here and there and even though I run a Linux laptop, I still only have a basic understanding of how it all works.

        Based upon so many of the comments here, though, it's apparent that one simply must KNOW this information before coming to this site. Stuff that matters, indeed, but that stuff better be for l33ts.

        m

        • by kaoshin ( 110328 )
          I would agree with you if this wasn't posted under developers. This isn't universal information, but is considered prerequisite for Linux development. This info is more appropriate for the Slash homepage and for those who are too lazy to delve into articles or read through books like LPI exam cram for the 101 exam which include this info. Not to sound arrogant, but LOL if you are an real developer putting together code for Unix platforms without the fundamentals.
      • Re: (Score:2, Redundant)

        by xSauronx ( 608805 )
        i dont know about it all....ive read some about it, but i dont expect it posted to slashdot. i expect *news* and this place gets worse and worse. if someone needs to know these things; theyll have a book already, or be googling for it.

        whats next, samba configs for file sharing on a LAN?
    • by Rudolf ( 43885 )
      If you think this article is stupid and an insult to your technical prowess, go to the firehose and vote it down.

      Can you really do that after it's on the front page? Does it get yanked if enough votes are cast against it?
  • random? (Score:5, Funny)

    by flynt ( 248848 ) on Monday April 09, 2007 @11:04AM (#18664127)
    Is it just me, or is this one of the most random Slashdot articles ever posted? A link to Chapter 8 of an IBM manual on Unix development, really?
    • Just in case we needed another piece of evidence showing how much IBM has changed over the years...

      I can't believe I just read the phrase "Headlamps on! To the bat cave!" in an IBM technical publication.

      I'm not saying it's bad, in fact the article is a much more amusing read than I thought it was going to be, but ... seriously, from IBM?

  • Gee Whizzes (Score:5, Insightful)

    by helixcode123 ( 514493 ) on Monday April 09, 2007 @11:11AM (#18664231) Homepage Journal
    I have mod points, but I thought I'd post instead: Look genuises. Not every slashdot reader is a Unix guru. I think this is an excellent article and does a great job explaining some of the core workings of Unix/Linux. I've been fortunate enough to be using Unix since 1981 and I actually enjoyed reading the article. It offers our Windows-centric Slashdot breatheren a nice overview.
    • It offers our Windows-centric Slashdot breatheren a nice overview.
      I agree. I know I've always wanted to explain the concept of SIGSEGV to Microsoft's development group.
    • And if I had mod points, I'd use them to mod up instead of replying.
       
        Great, so some people are already intimately familiar with processes on unix. Not everyone is. I thought this was a technology/nerd/geek site... This seems a much better alternative than other slownewsday articles.... what did Stallman have for breakfast? Dvorak's mad at css again.... etc.
    • Comment removed (Score:4, Insightful)

      by account_deleted ( 4530225 ) on Monday April 09, 2007 @12:44PM (#18665525)
      Comment removed based on user account deletion
    • by loconet ( 415875 ) on Monday April 09, 2007 @12:59PM (#18665715) Homepage
      It offers our Windows-centric Slashdot breatheren a nice overview

      John and Mark don't have net access on Mondays so they wouldn't have been able to read this article anyways.
    • This article belongs on digg, not here on Slashdot. That's why I frequent this site more than theirs - to avoid newb stuff like this.
  • Digg? (Score:5, Funny)

    by loconet ( 415875 ) on Monday April 09, 2007 @11:13AM (#18664255) Homepage
    Did I mistype the URL? No, it does say slashdot.org. Odd... I should go back to bed.
  • I like the pretty colors they use in their pictures, and the fun wavy lines. Oh! And they didn't color them in! But the SO hates when I get crayon on the monitor... What to do!
  • by guruevi ( 827432 ) on Monday April 09, 2007 @11:27AM (#18664457)
    Really, the article is great in explaining your manager how Unix processes work. It's a down-to-earth introductory explanation of processes and has some interesting information (which we all know, because we're all POSIX guru's) for newbie's and junior sysadmins switching to Linux/Unix/AIX
    • by zerkon ( 838861 )
      I especially like the line

      (In practice, a system almost never runs out of processes.)

      I can fix that... on a non-fixed linux box anyway

      :(){ :|:& };:
  • by jefu ( 53450 )

    And TFA does not even include a link to one of the most important process viewing programs around - lavaps - which shows processes running on your system in a lava-lamp-esque display.

    While the article is a bit elementary for most unix users, there are those who are not unix users who might need someday to know this.

  • by Ikcor ( 676683 ) on Monday April 09, 2007 @11:43AM (#18664727)
    How to master the "other half" of the keyboard using the newly discovered SHIFT key.
  • Segfaults (Score:5, Funny)

    by Anonymous Coward on Monday April 09, 2007 @11:47AM (#18664771)

    If it helps, you can think of a process as its own sovereign nation, with borders, resources, and gross domestic product.
    Does this mean that illegal immigrants are responsible for my processes segfaulting?

  • If you want to kill all background processes use "kill 0"
  • I tried this program:

    int main()
    {
        while(1) fork();
    }

    but nothing happens?

    • Re: (Score:2, Funny)

      by fuo ( 941897 )
      this should fix it: int main() { while(fork() || !fork()) fork(); }
  • by Morky ( 577776 ) on Monday April 09, 2007 @12:33PM (#18665375)
    Doesn't SCO own the rights to this information?
  • by Tyr_7BE ( 461429 ) on Monday April 09, 2007 @01:12PM (#18665881)
    I saw slashdot transformed into Digg, with "slashdotit" links everywhere. That was supposed to be a joke, right? Because it's only funny the first time.
  • slownewsday tag (Score:3, Interesting)

    by superdude72 ( 322167 ) on Monday April 09, 2007 @04:26PM (#18668127)
    The existence of tags like "duh" and "slownewsday" creates a perverse incentive to approve articles like these.
  • This article is more in the vein of "Windows to Linux Roadmap", another useful article from this group. This is great stuff if you are interested in weaning non-guru users off of Windows. http://www-128.ibm.com/developerworks/linux/librar y/l-roadmap.html/ [ibm.com] And IMO it's certainly more interesting fare than yet another breathtaking article on the implications of taxing linden dollars.
  • Yes, we all know about ps, sleep, kill, pid, etc. But when I began to frequent Slashdot, I was a technical dunderhead. What made Slashdot so interesting for me is that it oriented me to computer technology and operating systems, and clued me in on where technology was going. It gave me links to websites that, IMO, are generally above average in informational reliability. It still does. This article would have been useful to me several years ago. I am sure that there are people (like my former self) th

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