June 2019 - 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.

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Raspberry Pi 4
by Stewart Russell 04 Sep '19

04 Sep '19

More RAM, proper USB 3 and fast Ethernet, better processor, and dual HDMI output (incl 4K @ 60Hz): https://www.raspberrypi.org/products/raspberry-pi-4-model-b/

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UofT ssh shutdown?
by Peter King 28 Jun '19

28 Jun '19

Up until 3am on Wednesday, 26 June, I had a solid and reliable way to ssh into the UofT, talking to my computers (three of them) there; they would also provide redundant backup for my data every night. Well, without any warning, suddenly I can no longer ssh in to those computers -- all attempts to connect just time out. They are still running, I just can't get to them, and since I'm about 1000km away at the moment this is pretty rough. I talked to the JOG (Joint Operations Group) at the UofT, who had no real idea about this but pointed out that they had tightened their "security" recently because of a massive hole in RDP. I looked at the bug description and it didn't look like it had anything to do with ssh, and besides they did that a few weeks ago and everything was working for me perfectly until the day before yesterday. On the other hand, someone somewhere might have just decided it was easier to block all remote access -- though you'd think there would be a hue and cry were that so, and the JOG didn't know anything about it. The problem has been bucked over to the local UofT support group but the people on this list are far more knowledgeable, and more likely to have noticed problems, indeed to have solved them too. So I thought I'd ask. Has anyone noticed anything about ssh access to the UofT in the past few days? (The problem occurs on several different networks, accessing from computers as far away as Virginia and North Carolina, to one located in Toronto itself but not on the University network -- all have the same problem.) I've managed to come up with a workaround to be able to check/read email, but I would like to be able to ssh in to my other computers -- one runs a git server, for instance. All suggestions welcome! Thanks. -- Peter King peter.king(a)utoronto.ca Department of Philosophy 170 St. George Street #521 The University of Toronto (416)-946-3170 ofc Toronto, ON M5R 2M8 CANADA http://individual.utoronto.ca/pking/ ========================================================================= GPG keyID 0x7587EC42 (2B14 A355 46BC 2A16 D0BC 36F5 1FE6 D32A 7587 EC42) gpg --keyserver pgp.mit.edu --recv-keys 7587EC42

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Volunteer Opportunity at Toronto Botanical Garden
by Mark Stewart 28 Jun '19

28 Jun '19

Hello, I'm writing from Toronto Botanical Garden with a volunteer opportunity that may be of interest to some of your group members. We (TBG) are a small non-profit organization and currently lack any IT staff due to budgetary constraints. We're looking to set up an open-source DAM system on our in-house Linux server. If anyone might be interested in helping out, or knows someone who might, we'd love to connect with the right person/people. Thanks for taking a look! Here's a brief description of the project: Toronto Botanical Garden is looking for a volunteer with strong Linux skills to help us set up an open-source Digital Asset Management software on a designated, in-house server. The volunteer will work closely with TBG's Knowledge Resources Manager on this project. Our goal is to set up a DAM system to catalogue our digital assets, including images, video, and other electronic files. Some work has been done to select an appropriate open source DAM to suit TBG's needs, with Collective Access<https://www.collectiveaccess.org/> being a strong contender. The ideal volunteer will have previous experience working with, installing, and configuring DAM software. This project will greatly increase TBG's ability to leverage our digital assets for communication, outreach, and research. Thank you for considering. Hope you have a fantastic long weekend! Mark Stewart, MLIS Knowledge Resources Manager TORONTO BOTANICAL GARDEN 777 Lawrence Avenue East, Toronto, ON T. 416-397-1375 F. 416-397-1354 W. www.torontobotanicalgarden.ca<http://www.torontobotanicalgarden.ca/> UPCOMING EVENTS ZimSculpt, June 29 through September 8, 2019 VISIT TORONTO BOTANICAL GARDEN'S WESTON FAMILY LIBRARY<https://library.torontobotanicalgarden.ca/> Mon - Fri, 10am - 4pm Sat - Sun, 12pm - 4pm

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Screen vs Tmux
by William Park 26 Jun '19

26 Jun '19

Hi all, I try to use WSL (Windows Subsystem for Linux) whenever possible, even though I have VMware and VirtualBox available. One thing that WSL terminal lacks is "tab" that all other terminals have. So, that calls for Screen and Tmux. But, which one? And, why? -- William Park <opengeometry(a)yahoo.ca>

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Android / fastboot / ROM problem
by Evan Leibovitch 25 Jun '19

25 Jun '19

Hi all. I'm trying to determine if my Nexus 7 tablet (original 2012 version) is toast or can be fixed by software. Since its OS stopped being upgraded in 2015, I'd installed LineageOS on it some time ago. A few months ago when I went to upgrade, the install from TWRP didn't take and it just bootlooped on the Lineage animation about 15 seconds in. After trying a bunch of things I decided to just erase the whole thing and take it to factory settings. So, using these instructions <https://developers.google.com/android/images#nakasi>, I downloaded the factory ROM and tried to install. Here's what happened when executing the supplied install script: fastboot oem unlock (bootloader) Bootloader is already unlocked OKAY [ 0.015s] finished. total time: 0.015s fastboot erase boot erasing 'boot'... OKAY [ 0.015s] finished. total time: 0.015s fastboot erase cache ******** Did you mean to fastboot format this ext4 partition? erasing 'cache'... OKAY [ 0.015s] finished. total time: 0.015s fastboot erase recovery erasing 'recovery'... OKAY [ 0.015s] finished. total time: 0.015s fastboot erase system ******** Did you mean to fastboot format this ext4 partition? erasing 'system'... OKAY [ 0.015s] finished. total time: 0.015s fastboot erase userdata ******** Did you mean to fastboot format this ext4 partition? erasing 'userdata'... OKAY [ 0.026s] finished. total time: 0.026s fastboot -w update image-nakasi-ktu84p.zip target didn't report max-download-size sending 'bootloader' (2100 KB)... OKAY [ 0.262s] writing 'bootloader'... OKAY [ 0.601s] finished. total time: 0.863s rebooting into bootloader... OKAY [ 0.015s] finished. total time: 0.065s extracting android-info.txt (0 MB)... extracting boot.img (4 MB)... target didn't report max-download-size archive does not contain 'boot.sig' archive does not contain 'dtbo.img' archive does not contain 'dt.img' extracting recovery.img (5 MB)... archive does not contain 'recovery.sig' extracting system.img (628 MB)... archive does not contain 'system.sig' archive does not contain 'vbmeta.img' archive does not contain 'vendor.img' wiping userdata... Couldn't parse erase-block-size '0x'. Couldn't parse logical-block-size '0x'. mke2fs 1.44.6 (5-Mar-2019) /tmp/TemporaryFile-fnXNLB: Unimplemented ext2 library function while setting up superblock /usr/lib/android-sdk/platform-tools/mke2fs failed with status 1 mke2fs failed: 1 error: Cannot generate image for userdata Does this mean I have a hardware problem? I suspect if it is, the fix will be well more than the tablet is worth. Well, at least I know it's *probably* been wiped of any useful data, And yes, I've tried multiple ports, cables images and even systems. Thanks! -- Evan Leibovitch, Toronto Canada @evanleibovitch or @el56

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A find alternative: fselect
by Christopher Browne 20 Jun '19

20 Jun '19

Having recently been at a database conference, somewhere along the line, someone pointed out this tool, "fselect", which is basically what you get if you take /usr/bin/find, and change it to have a command line that looks like SQL rather than the odd-ish find arguments: https://github.com/jhspetersson/fselect $ fselect path, size from ~/Downloads where size gt 30mb order by size desc limit 25 /home/cbbrowne/Downloads/flyway-commandline-4.0.3-linux-x64.tar.gz 53991744 /home/cbbrowne/Downloads/HP41C.pdf 53174535 /home/cbbrowne/Downloads/Tai chi/WuDang sword.mp3 44784426 /home/cbbrowne/Downloads/civic-manual-2019.PDF 42192497 /home/cbbrowne/Downloads/HP-41CXOwnersManualVol1.pdf 39603314 Hmm. Looks like there's some crud I might want to get rid of, and a few calculator manuals :-) FYI, fselect is written in Rust, and has a goodly number of ("painfully large number of") dependencies, quasi-self-managed via the Rust-oriented dependency tool, Cargo. The dependency description is pretty commendable; it is pretty decently self-descriptive. See: https://github.com/jhspetersson/fselect/blob/master/Cargo.toml Using fselect to search for things is, I suppose, my experiment of the month. Will see how it grows on me. The output is intended to be human readable moreso than machine readable. (That said, how many of us still use /usr/bin/find to generate input for cpio???) -- When confronted by a difficult problem, solve it by reducing it to the question, "How would the Lone Ranger handle this?"

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[GTALUG-Announce] Lightning Talks
by hi＠gtalug.org 19 Jun '19

19 Jun '19

<https://gtalug.org/meeting/2019-07/> # 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 already have a topic in mind please send an email speakers(a)gtalug.org to be added to the list of scheduled talks. If you would like to give a talk during the meeting, 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 gets selected, you will have five to present your idea, then five minutes of audience questions. ## Location George Vari Engineering and Computing Centre 245 Church Street, Room 203 Ryerson University <https://goo.gl/maps/16oJ2> <https://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: <https://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

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Calling all networking and SVN gurus
by Giles Orr 12 Jun '19

12 Jun '19

To forestall the inevitable suggestion: no, the solution is not to move to git. At least not yet: for various reasons, it can't happen right now. This is the last holdout, all our other repos are already git. I apologize for the length of this dissertation: I've been doing my homework as fast as I can, and I want to provide complete information. I've just moved a previously semi-local (different building but "on campus") SVN server to a cloud instance (running Debian, SVN 1.9.5, and Apache 2.4.25, access via https://). For the most part it went smoothly, but now our "on campus" Jenkins server intermittently loses the network connection on 'svn up' so the deploy fails. That's bad. What's far worse is that while Jenkins initially resumed these broken updates politely when the deployment was re-run, it's now decided that these resumes have left a locked workspace and it has to do a fresh checkout. One of the problems with moving this repository to git is that SVN trunk is ~5G in size: a checkout to a local client takes 5-10 minutes, but for some reason a Jenkins checkout takes about 30 minutes (this is all pretty new to me, and I haven't had time to investigate that time difference yet). An update takes a 60 seconds, but a new checkout takes 30 minutes - you can see where that causes delays in deployment. One possible mitigation is to trap the SVN failure, do a clean-up on the directory and re-run. I may have to try this, but ... that's just mitigation, not a solution. The Jenkins server is on Windows (I wasn't given a choice) and mostly works well. It uses Cygwin for all the SVN stuff (SVN version 1.11.x). It's also at a different physical location from me with different network rules. The critical lines of the failure error: org.tmatesoft.svn.core.SVNException: svn: E175002: Connection reset svn: E175002: REPORT request failed on '/svn/repo/!svn/vcc/default' (It being Java, the errors run to 40 or 50 lines: I think this is the only part that's important.) Unfortunately, this is one of those errors that Google searches produce lots of questions, lots of speculations ... and no solid answers. At least not that I've found. Likewise, a lot of people want to know, as I did, about the relatively unusual filepath ("!svn/vcc/default") but I've never seen a solid answer as to what that's about either. The logs show Jenkins requests against that filepath with both REPORT and PROPFIND, but Jenkins is only failing on REPORT. Both of these request types are WebDAV extensions. Our staff don't seem to be having any trouble checking out or updating the repository across a mix of Windows and Mac clients. I've so far failed at getting more logging out of SVN and Apache: what I do have doesn't tell me much useful, at least not related to these failures. This problem is intermittent and infrequent. I'm thinking the next step is network sniffing - although I'm hoping someone can suggest something better. I'm relatively inexperienced with Wireshark and tcpdump (and SVN ...), but what experience I do have suggests all I'm going to get is to learn that SVN stopped providing data without finding out why or how to fix it. Any suggestions welcomed, thanks. -- Giles https://www.gilesorr.com/ gilesorr(a)gmail.com

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POP3 vs IMAP
by o1bigtenor 11 Jun '19

11 Jun '19

Greetings Working on setting up Claws - - an email handling tool and I need to choose whether I use POP3 or IMAP. What I've been able to find so far doesn't really give any kind of clear direction. I have lots of storage here and am planning on starting with my least used addresses just to make sure things are working well before I do a complete switch. Please advise. TIA

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