May 2018 - Talk - lists.gtalug.org

war story: power failure makes CentOS system unbootable
by D. Hugh Redelmeier 30 Sep '22

30 Sep '22

tl;dr / spoiler: change fstab so that /boot/efi is not automatically mounted. See the recommendation at the end of this message. My gateway computer is a little PC running CentOS. It does not come back after a power failure. The reason (as best I can tell) is interesting and I think that I have a fix. My system is UEFI. It boots from a UEFI system partition, known as /boot/efi to Linux. If this gets corrupted, it won't boot. It is a VFAT partition. On my gateway (a Zotac Zbox RI321, a cute little box with two ethernet ports), the UEFI firmware apparently won't boot if the dirty bit is set in the system partition. CentOS normally runs with /boot/efi mounted. So when the system isn't shut down cleanly, the dirty bit will be on. Consequence: the system is not going to boot after a power failure. Odd observation 1: if I put a live Fedora 25 USB stick in the system and try to boot in this otherwise-unbootable state, CentOS boots from the main disk. So this really looks like a firmware bug/quirk. Odd observation 2: fsck doesn't seem to automatically fix the system partition. Once CentOS 7 booted, I dismounted /boot/efi and did an fsck on it. $ sudo fsck /dev/sda1 fsck from util-linux 2.23.2 fsck.fat 3.0.20 (12 Jun 2013) 0x25: Dirty bit is set. Fs was not properly unmounted and some data may be corrupt. 1) Remove dirty bit 2) No action ? 1 Leaving filesystem unchanged. /dev/sda1: 16 files, 2420/51145 clusters Googling got me to <https://www.centos.org/forums/viewtopic.php?t=50917> In particular, this advice seemed quite good: ==== recommendation ==== Two other changes I recommend for UEFI systems, to each OS's /etc/fstab. - For the /boot/efi mountpoint, add the mount options x-systemd.automount,noauto - Change fs_passno (last column) to a 1 or 2; the canonical fstab instructions suggest 2, but systemd treats 1 and 2 as the same. The first change means the EFI System partition will not be automatically read-write mounted at boot time; it's a bad idea this is the default because it puts the ESP at risk especially if ther are crashes, FAT has no journal and will therefore always be marked dirty in such a case; no other UEFI OS mounts the ESP by default. Second, if anything tries to access /boot/efi (read or write), systemd will automatically mount it, and because of the fs_passno 1 or 2, it will fsck it first and that fixes and clears the dirty bit in case it's set. Right now without these changes, it's just a matter of having the right number and bad timing of crashes to render the EFI System partition corrupt.

3 9

glittery cheap but useless toy computers
by D. Hugh Redelmeier 30 Sep '18

30 Sep '18

The price of this looks very attractive: <https://www.zapals.com/nexbox-a95x-tv-box-4k-android-7-1-amlogic-s905w-quad…> - US$23.99, with free (very slow) shipping, probably no tax - only FullHD - 1G RAM, 8G eMMC (a little light) - Amlogic S905w: quad core Arm Cortex A53 processor; penta core Mali 450MP GPU. There are a lot of cheap boxes meant for running Kodi and this is one of them. Technically, they run Android and easily hook up to your TV. But they don't run Android TV (a subtle but important difference). Because of "Digital Rights Management", they cannot run Netflix at a good resolution. I don't remember if YouTube also limits them. So what's left? Unauthorized content discovered through Kodi plug-ins. I've never tried this. I understand that there is a large turnover in plug-ins as they get taken down. For TV use, I much prefer a Xiaomi Mi Box with genuine Android TV (US$70 from US Walmart). BUT. The raw hardware for these cheap boxes is interesting. Faster than a Raspberry Pi. And these come with a box, remote control, and power supply. Expandability and openness in general is a lot worse. The worst thing is that all their GPUs are proprietary (and a few other things too) so you cannot drop an ordinary Linux on them. I think that they all use uboot and device tree, but in an idiosyncratic way, adding to the difficulty. I bought a (less) cheap S912 box that I intend to play with. Apparently you can run Linux on these if you don't need video output. I won't give links because I don't know which efforts are the best.

1 1

Help need in bash
by Stephen 01 Jun '18

01 Jun '18

I want to build a script to convert any *.png files to *.jpg files using convert. Doing manually works fine. Building a script has presented problem. I am well versed in programming but a novice with bash. My loop through the files works fine. #!/bin/bash cd /big1/memes/; shopt -s nullglob for f in "*.png" do echo $f done I get a list of filenames with an extension of .png But when I try to get the basename with: #!/bin/bash cd /big1/memes/; shopt -s nullglob for f in "*.png" do echo $f b=${f%.png} echo $b done I first get a list of the .png files, then a list of all files, both the existing .jog and the .png. This gets a WTF reaction from me. Can someone explain and help me get closer to getting this to work? Thanks -- Stephen

9 16

[GTALUG-Announce] GTALUG Meeting on Tuesday 12 June at 7:30pm
by hi＠gtalug.org 30 May '18

30 May '18

<http://gtalug.org/meeting/2018-06/> # Lightning Talks Lighting Talks is GTALUG's version of an un-conference, a loosely structured short talks emphasizing the informal exchange of information and ideas between participants, rather than following a conventionally structured GTALUG meetings. If you would like to give a talk, all you have to do is write your name on a post-it and stick it on the whiteboard in the front of the room. When your talk get's picked you will have five uninterrupted minutes for you to present your idea, then five minutes of audience questions. Pre-Registers Lightning Talks include: * Cipher Suites for Nginx and HAProxy w/ Giles Orr * Making the case for CASE, or: Why I Love Conditional Expressions in Postgres, SQLite, and MySQL w/ Myles Braithwaite ## Location George Vari Engineering and Computing Centre 245 Church Street, Room 203 Ryerson University <http://goo.gl/maps/16oJ2> <http://www.openstreetmap.org/way/23447525> ## Schedule * 6:00 pm - Please discuss on the general mailing list (i.e. <talk(a)gtalug.org>) where you want to go for dinner. * 7:30 pm - Meeting and presentation. * 9:00 pm - After each meeting, a group of GTALUGers move to The Imperial Pub (54 Dundas St East) for refreshments and more socialising. # Code of Conduct We want a productive happy community that can welcome new ideas, improve every process every year, and foster collaboration between individuals with differing needs, interests and skills. We gain strength from diversity, and actively seek participation from those who enhance it. This code of conduct exists to ensure that diverse groups collaborate to mutual advantage and enjoyment. We will challenge prejudice that could jeopardise the participation of any person in the community. The Code of Conduct governs how we behave in public or in private whenever the Linux community will be judged by our actions. We expect it to be honoured by everyone who represents the community officially or informally, claims affiliation or participates directly. It applies to activities online or offline. We invite anybody to participate. Our community is open. Please read more about the GTALUG Code of Conduct here: <http://gtalug.org/about/code-of-conduct/>. If you have any questions, comments, or concerns about the GTALUG Code of Conduct please contact the GTALUG Board @ <board(a)gtalug.org>. --- GTALUG Announce mailing list announce(a)gtalug.org https://gtalug.org/mailman/listinfo/announce

1 0

Video issue? boot screen has weird mixed lower case/capitals, no X or consoles
by Glen Strom 28 May '18

28 May '18

I'm running Slackware 14.2, 32-bit. The computer is an HP xw4600 desktop workstation. The video card is an Nvidia Quadro NVS 290 PCI Express. I use an Nvidia legacy driver (it's an old machine, probably going on 10 years old.) I stepped away from the machine for a while, and when I cam back the monitor was fluctuating rapidly and everything was frozen. I had to use the Magic System key to reboot. Upon rebooting, the initial screen had a series of blue vertical lines running through it. The lilo screen looked fine. When the OS booted I saw a string of numbers followed by a bizarre combination of upper and lower case text. The boot up sequence ran correctly right up until the machine went into runlevel 4. The screen stayed dark. I couldn't even switch to a console--nothing would show. I don't have another video card to try. Does this sound like a video card issue or might it be something else? I didn't find anything helpful on searching for an answer. -- Glen Strom gstrom57(a)gmail.com

2 1

Can't boot using Xorg, only Wayland works on Ubuntu 18.04
by Jim Ruxton 25 May '18

25 May '18

I recently updated to Ubuntu 18.04 and cannot boot using Xorg only Wayland. I have tried reinstalling xorg, reinstalling nvidia drivers, setting |WaylandEnable=false| in |/etc/gdm/custom.conf| but whenever trying to login using Xorg I get a frozen screen and mouse. I am using the latest nvidia-390 driver. My laptop has a dual graphics card ie. Intel and Nvidia. I would be fine staying with Wayland however it seems unstable and a dual monitor setup isn't working. Any thoughts what I can do to get this working so I can use Xorg . Thanks, Jim

4 14

GTALug Lightning Talk, possible topic: Tracking Bots on your web site
by Don Tai 21 May '18

21 May '18

Hi Mylees, I was thinking it would be interesting to talk about internet bots and how they can affect your web site. It is a very wide topic, but I can summarize down to a short talk for any/all these items: -web traffic, what is a bot, good and bad bots -tracking bot activity on your site: using your raw access log -identifying a bot: tracking down their origins/owners -good vs bad bot activity -humans vs bot behaviour -banning them from your site I have done some of this talk before for a Wordpress Toronto group: https://wptoronto.com/2016/10/fighting-spam-wordpress/ What do you think? Don.

1 0

Malware talk from May meeting is availabe on youtube
by Alex Volkov 21 May '18

21 May '18

Hey Everyone, Now you can watch Malware! talk with Garry Pejski from our May 2018 meeting on Youtube. https://youtu.be/QBVQorW3Wlc Alex.

1 0

Fedora 27 packagekit reboot and install glitch
by Russell 19 May '18

19 May '18

After installing some recent F27 updates using the gnome software centre, the package kit watchdog has stopped exiting gracefully on an install routine. This happened after I chose to enable the recommended updates. The watch job wouldn't quit watching and I'd have to forcefully reboot, as the system would hang for a very long time. This is one of the few times I have given a linux a nominal three finger salute. Seven ctl-alt-del combos in two seconds stopped the job and shutdown eventually happened about two minutes later. My temporary solution is to mask the packagekit application service and only use dnf. Dragora's gui is also easy, however, the desktop integration is not as slick. I do like the native gnome software centre interface and the way the monitoring and notification app is tied into the calander. It is very central and easy to deal with. However for the time being; #systemctl mask packagekit.service Created symlink /etc/systemd/system/packagekit.service → /dev/null. I had been looking for a way to stop only the notification that F28 is now available as an upgrade. I'd get that notice once every day, but apparently if the watchdog is running, you get all notices and I have yet to discover a way to blacklist an individual notice, so I masked the entire service. I guess this is part of the bumps and bruises of switching over to systemd. I am trying out F28 on my M.2 Xpoint ram stick and I'm pretty pleased so far. The only issue which keeps me with F27 as main, is on par with every distro update I have ever done. ie. the sane backend and its D-bus internal references. On F28 my brother MFC-L2710DW cannot connect to the brscan. Following the sane systemd recomendations I've gotten to the socket via telnet, but I just can't glue the endpoints together. Hopefully Brother will repackage the driver as systemd takes over Fedora init entirely. -- Russell

4 8

Sending array variable over CGI ?
by William Park 18 May '18

18 May '18

Hi all, If I'm sending single valued data over web, eg. a=111, b=222, c=333, then I can do http://.../xxx.cgi?a=111&b=222&c=333 How do I send array data, like A[1]=111, A[2]=222, A[3]=333 to a CGI script? I don't think I can do something like http://.../xxx.cgi?A[1]=111&A[2]=222&A[3]=333 Or, can I? I have seen a same variable repeated, http://.../xxx.cgi?A=111&A=222&A=333 but that means the CGI script has to build the array. -- William Park <opengeometry(a)yahoo.ca>

6 7