- Roundtable - muug.ca

LTSP demo
by Mike Pfaiffer 10 Oct '12

10 Oct '12

I mentioned this at last nights meeting. This is just a follow-up. Not necessarily a MUUG thing but a Linux thing none the less. At next months MWCS meeting on November 6'th (one week before the MUUG meeting) I will be giving a demo of a working LTSP system. I will spend 10 minutes describing the process I used to get it working and the rest of the evening will be an exploration of the system. If there is an expert reading this post who would like to contribute, feel free to drop by and take over after I do my bit. The address for the meeting will be 3390 Portage Avenue on the South side (between Westwood and Caviller - I think that's the general area). Land marks are the Safeway and McCardboard on the North side of Portage as well as the Princess Auto and Giant Tiger a block or so to the East on the South side. The time is 7:00 - 9:00 sharp. Parking is in the rear of the church. Enter through the back door and head down stairs. A bit about what to expect from the MWCS. The group is a generic computer club. We don't care what sort of computer people run. The ability level of the club is somewhat less than that of the MUUG. It is also substantially smaller than the MUUG with resources to match. We don't even have an internet connection available to us. The MWCS web page can be found at http://mwcs.mb.ca. For follow-up... Questions about the LTSP can (and logically should) be handled through the mailing list. Questions about the MWCS will be handled privately through e-mail. Later Mike

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Re: [RndTbl] Screen in production
by Adam Thompson 10 Oct '12

10 Oct '12

IIRC, stderr doesn't buffer, stdout does. Both must block eventually once they hit the maximum buffer size the kernel and/or libc impose. Buffering != blocking. -Adam Robert Keizer <robert(a)keizer.ca> wrote: >On 12-10-10 10:33 AM, Gilbert E. Detillieux wrote: >> On 2012-10-10 09:50, Robert Keizer wrote: >>> I have a production service that prints some debug to stdout. I could >>> make it print to stderr, but it really doesn't matter in this case. >> >> Are you sure it doesn't matter? Read on... >> >>> I want to have some hope of if something goes wrong figuring out what >>> did. >>> Log files aren't really an option so I ran it in screen. Yes yes I could >>> have made it network log to somewhere else, but again, not really an >>> viable option in this case. Works great as the program dies and the >>> output stops, leaving the last debug messages in the buffer of screen. >> >> One of the classic C/UNIX lessons about stdout vs stderr is that the C >> library buffers stdout by default but not stderr, exactly for the >> reason that you want error messages to be flushed out right away, >> leaving nothing in the buffer. This is particularly important if the >> program dies in a way that prevents the usual exit processing, such as >> flushing buffers and closing file I/O. >> >> So, issues with "screen" aside, you probably should either send your >> debug output to stderr, or set your stdout to unbuffered mode while >> debugging (or both). >> > >Interesting! > >Thought I'd test out stdout vs stderr just to see if this was in fact >the case. It's not - stderr and stdout have the same effect in this case. > >Below is a script the listens for incoming data on a given port ( >example is 1337 ). When data is received it writes to either stdout or >stderr and then sends data on to another port ( in this case 1338 ). >This script also fills up the screen buffer by a simple loop ( tested >filling with both stderr and stdout ). > >Using telnet to feed the script data, and nc ( nc -lk 1338 ) to listen >on port 1338 for the output, one can test to confirm. > > >net = require "net" >server = net.createServer ( c ) -> > c.setEncoding "utf8" > c.on "data", ( data ) -> > _c = net.createConnection 1338, ( ) -> > process.stderr.write "Data: " + data + "\n" > _c.write data > _c.end( ) > >server.listen 1337, "127.0.0.1" >loops = ( ) -> > process.stderr.write "Loopies: " + Date( ) + "\n" > setTimeout loops, 100 >loops( ) > >Screenshot is attached - it shows this script in the top left running in >screen, with copy mode enabled. Right of it is the telnet session >feeding it, and on the bottom left is the nc or "output". Note that the >last two inputs did not make it to the output. Ergo, unless I'm totally >an idiot in my implementation: This is blocking on stderr as well. > >Thoughts? Because now I'm officially annoyed that this blocks on stderr >as well! > >Rob > > >_______________________________________________ >Roundtable mailing list >Roundtable(a)muug.mb.ca >http://www.muug.mb.ca/mailman/listinfo/roundtable

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Screen in production
by Robert Keizer 10 Oct '12

10 Oct '12

Greetings, I've been running screen for a while now - I use it day to day operations just fine, and occasionally when I'm in a pinch I use it for a serial terminal. The way you scroll up in screen ( or atleast the way that I've found that seems to be standard ) is to use ctrl + a then [. This puts you into "copy mode", and there are some nice features in there. My issue was thus: I have a production service that prints some debug to stdout. I could make it print to stderr, but it really doesn't matter in this case. I want to have some hope of if something goes wrong figuring out what did. Log files aren't really an option so I ran it in screen. Yes yes I could have made it network log to somewhere else, but again, not really an viable option in this case. Works great as the program dies and the output stops, leaving the last debug messages in the buffer of screen. Enter problem: Disconnecting from the screen ( ctrl+a ) d, leaving it in copy mode. Turns out that screen _blocks_stdout_ while it is in copy mode. Depending on what kind of program you're running in screen this could be bad. In my case it was pretty annoying because _monitoring_didn't_catch_it_ as the program was still responding to tcp connections. It was block writing to stdout. Because the blocking stdout command was in its own function and I am using an async javascript program without waiting for a callback, other parts of the system still worked. Thought I'd share. Make sure you hit esc+esc on production screen stuff.. it blocks stdout! Rob

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Blackberry 9700 ...
by Dan Keizer 10 Oct '12

10 Oct '12

Hi guys - I forgot to mention at the meeting yesterday ... I thought I'd let you guys have first dibs if you're interested. I have a spare Blackberry Bold 9700 phone I'll be looking to sell soon. It is originally on the Rogers network, but is unlocked and will take any SIM card. (I've tested it with a talk mobile SIM and a 7-11 speakout sim). It is in near-mint condition and is still actively in service. Reason I'm selling, is I'm doing some android development and want a spare android phone for testing. (I don't need 3 phones). First 120$ can take it ... contact: email me, or 204-666-1919. Thanks. Dan.

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Clay Shirky: How the Internet will (one day) transform government | Video on TED.com
by Bill Reid 09 Oct '12

09 Oct '12

This is a very interesting presentation by Shirky. He makes the case that the use of Git provides a new way of transforming the interaction between government and citizens. Is anyone aware of Git being used by governments in Manitoba? http://www.ted.com/talks/clay_shirky_how_the_internet_will_one_day_transfor… Enjoy, Bill

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MUUG Meeting, Oct 9, 7:30pm -- Arduino Microcontroller
by gedetil＠cs.umanitoba.ca 02 Oct '12

02 Oct '12

The Manitoba UNIX User Group (MUUG) will be holding its next monthly meeting on Tuesday, October 9. The meeting topic for this month is as follows: Arduino Microcontroller Sean Walberg, a local network administrator, web developer, tech writer and editor, will show us what we can do with the Arduino open-source microcontroller. To allow for a longer round-table session and break, we'll be skipping the RTFM segment of the meeting. Plus, this month's meeting is the MUUG annual general meeting, which included the election of the MUUG board of directors for the 2012-2013 year (which will be by acclamation). The group holds its general meetings at 7:30pm on the second Tuesday of every month from September to June. (There are no meetings in July and August.) Meetings are open to the general public; you don't have to be a MUUG member to attend. ********************************************************************** Please note our meeting location: The IBM offices, at 400 Ellice Ave. (between Edmonton and Kennedy). When you arrive, you will have to sign in at the reception desk, and then wait for someone to take you (in groups) to the meeting room. Please try to arrive by about 7:15pm, so the meeting can start promptly at 7:30pm. Don't be late, or you may not get in. (But don't come too early either, since security may not be there to let you in before 7:15 or so.) Non-members may be required to show photo ID at the security desk. Limited parking is available for free on the street, either on Ellice Ave. or on some of the intersecting streets. Indoor parking is also available nearby, at Portage Place, for $5.00 for the evening. Bicycle parking is available in a bike rack under video surveillance located behind the building on Webb Place. ********************************************************************** For more information about MUUG, and its monthly meetings, check out their Web server: http://www.muug.mb.ca/ Help us promote this month's meeting, by putting this poster up on your workplace bulletin board or other suitable public message board: http://www.muug.mb.ca/meetings/MUUGmeeting.pdf -- Gilbert E. Detillieux E-mail: <gedetil(a)muug.mb.ca> Manitoba UNIX User Group Web: http://www.muug.mb.ca/ PO Box 130 St-Boniface Phone: (204)474-8161 Winnipeg MB CANADA R2H 3B4 Fax: (204)474-7609

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Re: [RndTbl] Roundtable Digest, Vol 93, Issue 14
by Michael Doob 27 Sep '12

27 Sep '12

On 12-09-27 12:00 PM, roundtable-request(a)muug.mb.ca wrote: > Send Roundtable mailing list submissions to > roundtable(a)muug.mb.ca > > To subscribe or unsubscribe via the World Wide Web, visit > http://www.muug.mb.ca/mailman/listinfo/roundtable > or, via email, send a message with subject or body 'help' to > roundtable-request(a)muug.mb.ca > > You can reach the person managing the list at > roundtable-owner(a)muug.mb.ca > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Roundtable digest..." > > > Today's Topics: > > 1. Re: bash script for printing lines that don't match? > (Grigory Shamov) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 27 Sep 2012 15:13:56 +0000 > From: Grigory Shamov <Grigory.Shamov(a)ad.umanitoba.ca> > To: Continuation of Round Table discussion <roundtable(a)muug.mb.ca> > Subject: Re: [RndTbl] bash script for printing lines that don't match? > Message-ID: <CC89D6B2.B1C4%Grigory.Shamov(a)ad.umanitoba.ca> > Content-Type: text/plain; charset="us-ascii" > > Hi, > > Not in bash, but awk: will show what is in file1 but not in file2 > > awk 'FNR == NR {arr[$0];next} !($1 in arr) {print}' file1 file2 > > > I've used this to compare lists of rpms on our machines. > > Have you used diff, perhaps in conjunction with sort? If so, what didnt' work? -- ------------------------------------------------------------------ Michael Doob Telephone: (204) 474-9796 Department of Mathematics Fax: (204) 474-7606 University of Manitoba email: Michael_Doob(a)umanitoba.ca Winnipeg, MB, Canada R3T 2N2 ------------------------------------------------------------------

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bash script for printing lines that don't match?
by John Lange 27 Sep '12

27 Sep '12

I think I've asked this in the past but try as I might I can't remember what the answer was or figure out how I solved it before. I have 2 files that are nearly identical and I need to know which lines in the two files do _not_ match. I can think of some relatively complex loops with grep etc. which would probably work (for every line in file A, grep in file B etc.) solve the problem but I'm hoping for something more elegant. I thought at first that perhaps "join" would do it but even though it will provide left and right joins, there is no way to prevent it from outputting the matching lines. Any ideas? John

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Re: [RndTbl] boot and install from USB key
by Adam Thompson 24 Sep '12

24 Sep '12

Seconding that, doing anything - particularly configuration - at the command line in pfSense is discouraged. I did a presentation about it in April this year, the recording of which is online at the website. -Adam tim(a)fractaldragon.net wrote: >(trying again from a real keyboard) > >On Sun, Sep 23, 2012 at 11:21:56PM -0500, Dan Martin wrote: > >> pfSense looks good. Documentation a little less clear than IPCop, >> but good reviews. It will mean learning about pf, and abandoning my >> experience with iptables. > >Hi Dan, > >The web GUI is decent for many tasks, so you may find that you can get >by without digging into pf. > > Cheers, > Tim >_______________________________________________ >Roundtable mailing list >Roundtable(a)muug.mb.ca >http://www.muug.mb.ca/mailman/listinfo/roundtable

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Re: [RndTbl] boot and install from USB key
by Adam Thompson 24 Sep '12

24 Sep '12

Time to either downgrade your expectations, downgrade your hardware, or upgrade your software. What do you want to use IPCOP for, anyway? Just a simple firewall? Dan Martin <ummar143(a)shaw.ca> wrote: > >On 2012-09-23, at 3:13 PM, Adam Thompson wrote: > >> Sounds like IPCOP isn't compatible with your hardware. Isn't it based on a fairly old kernel? If this is a brand-new machine, its SATA controller might not even be recognized by that kernel. >> Have you tried any other Linux distro or LiveCD on this hardware? >> -Adam >> >> _______________________________________________ >> Roundtable mailing list >> Roundtable(a)muug.mb.ca >> http://www.muug.mb.ca/mailman/listinfo/roundtable > > >I think you are right, Adam. > >I tried dd'ing directly to a SATA drive, put it in the machine, and it again booted but this time IPCop setup could not find hard drives. > >I googled the "No hard disk found" error and found >http://www.ipcops.com/phpbb3/viewtopic.php?p=82706 >> >> Post subject: Re: During installation error "No Hard Disk found"Posted: Sat Jan 14, 2012 9:55 pm >> VonSkippy wrote: >> @taustin - It WILL be part of the NOT YET RELEASED version 2.1.0 >> >> Which is vaporware, at least for now. > >IPCop v1.9.x is based on a 1.4 kernel. I don't know what kernel IPCop v2.0.3 uses, but I'm guessing it can't see my SATA drive, and I have no IDE drives in the machine. > >Yikes. I have an old pentium with an IDE drive with XP on it - but only 1 ethernet port. I'd hate to rob my new machine of it's PCI network cards to stick in the old clunker! > >Dan Martin >GP Hospital Practitioner >Computer Scientist >ummar143(a)shaw.ca >(204) 831-1746 >answering machine always on > > >_______________________________________________ >Roundtable mailing list >Roundtable(a)muug.mb.ca >http://www.muug.mb.ca/mailman/listinfo/roundtable

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