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by jojopi
Thu Dec 02, 2021 1:07 pm
Forum: Troubleshooting
Topic: very strange character replacements
Replies: 5
Views: 268

Re: very strange character replacements

This is why i'm looking for a possible image/program or something that i can "run" on a stripped down installation, so that i can verify that the problem is with the board, and nothing else. I do not understand what you are hoping to test here. The problem does not look like a software bu...
by jojopi
Thu Dec 02, 2021 12:14 pm
Forum: Troubleshooting
Topic: pigpiod -l option only opens ::1
Replies: 1
Views: 71

Re: pigpiod -l option only opens ::1

A network server program must create a socket(), bind() it to a local address and port, listen() on it, and then accept() connections. Each socket can only be bound to one address and port, so to listen on multiple distinct addresses would require multiple sockets. I think pigpiod -l prefers to bind...
by jojopi
Wed Dec 01, 2021 2:51 pm
Forum: Troubleshooting
Topic: Weird update error
Replies: 3
Views: 102

Re: Weird update error

pwillard wrote:
Wed Dec 01, 2021 1:54 pm
E: Problem with MergeList /var/lib/apt/lists/raspbian.raspberrypi.org_raspbian_dists_bullseye_main_binary-armhf_Packages
You can just sudo rm that file, and apt will download it again.

However, 0ad is literally the first package of 61500. There may well be other issues with the card or image.
by jojopi
Wed Nov 24, 2021 4:22 pm
Forum: General
Topic: A 'minicom' gotcha
Replies: 2
Views: 144

Re: A 'minicom' gotcha

That is correct terminal behaviour if DEC AutoWrap Mode is disabled (either by configuration or by printf "\033[?7l"). The cursor sticks in the final column and repeatedly overwrites the previous character until moved. screen, xterm, lxterminal all do it this way. But they all have AWM ena...
by jojopi
Wed Nov 24, 2021 10:12 am
Forum: Troubleshooting
Topic: very strange character replacements
Replies: 5
Views: 268

Re: very strange character replacements

Looking at an ASCII table, all of the incorrect characters are caused by single bit flips. All of them are errors in bit 4. Most of them are in the direction that the printed character has bit 4 clear, while the intended character had bit 4 set. In addition, all of the errors are in the third charac...
by jojopi
Fri Nov 19, 2021 7:39 pm
Forum: Beginners
Topic: Resister Values
Replies: 31
Views: 896

Re: Resister Values

You could short GPIO without any problem! It is current limited (max ~16ma on output). Not quite true. The drive strength is the maximum current at which the output will still meet the correct voltage limits; it is not a current limit. Exceeding the maximum current is dangerous. Much less dangerous...
by jojopi
Fri Nov 19, 2021 6:36 pm
Forum: General discussion
Topic: ..is apparently in use by the system; it’s not safe to run badblocks!
Replies: 11
Views: 527

Re: ..is apparently in use by the system; it’s not safe to run badblocks!

It is possible that the unreadable blocks are part of the free space, not used by any file. The commands to check are like: pi@tau:~ $ sudo debugfs /dev/mmcblk0p2 debugfs 1.46.2 (28-Feb-2021) debugfs: icheck 99999 Block Inode number 99999 36259 debugfs: ncheck 36259 Inode Pathname 36259 /home/pi/sha...
by jojopi
Fri Nov 19, 2021 4:00 pm
Forum: General discussion
Topic: ..is apparently in use by the system; it’s not safe to run badblocks!
Replies: 11
Views: 527

Re: ..is apparently in use by the system; it’s not safe to run badblocks!

I do not understand how you installed dd_rescue, since I cannot find a package that provides that any more. I also do not understand how you failed to install GNU ddrescue from package gddrescue in Raspbian. I agree that excessive retrying is unproductive. On magnetic media the head will pick up a s...
by jojopi
Fri Nov 19, 2021 8:34 am
Forum: General programming discussion
Topic: simulate a tree command using Shell Script that displays all the directories recursively
Replies: 2
Views: 215

Re: simulate a tree command using Shell Script that displays all the directories recursively

The standard (POSIX) shell is not a good choice of language for this problem. You have to be very careful about spaces and other special characters in file and directory names. There are no local variables other than parameters, so writing a recursive function with the degree of context required for...
by jojopi
Fri Nov 19, 2021 3:04 am
Forum: Beginners
Topic: Resister Values
Replies: 31
Views: 896

Re: Resister Values

ame wrote:
Fri Nov 19, 2021 12:19 am
No resistor necessary, and it's the canonical way to connect a pushbutton.
The resistor is not strictly required in either case (it could be just a wire). But it protects against short circuit if the GPIO is accidentally programmed as an output, and the button pressed. So it is recommended.
by jojopi
Mon Nov 15, 2021 5:46 pm
Forum: Raspberry Pi OS
Topic: Check new kernel-version before actually running "apt-get upgrade"?
Replies: 6
Views: 311

Re: Check new kernel-version before actually running "apt-get upgrade"?

The "cryptic" package version numbers consist mainly of the date of release in format YYYYmmdd. The site with the driver files has last modified times in format YYYY-mm-dd HH:SS. (The timezone is not clear.) I think apt policy raspberrypi-kernel is more readable than the verbose simulation...
by jojopi
Mon Nov 15, 2021 12:19 pm
Forum: General discussion
Topic: ..is apparently in use by the system; it’s not safe to run badblocks!
Replies: 11
Views: 527

Re: ..is apparently in use by the system; it’s not safe to run badblocks!

First of all, have you tried badblocks without the -n ? Unless it actually finds unreadable blocks, there is no need to do a read-write test. If it does find unreadable blocks, fully rewriting the entire partition may not be the best way to fix them. I would also be inclined to suspect your SD card ...
by jojopi
Mon Nov 15, 2021 11:37 am
Forum: General discussion
Topic: special device /dev/mmcblk0p2 does not exist
Replies: 3
Views: 145

Re: special device /dev/mmcblk0p2 does not exist

It is actually okay in recent Linux to mount a filesystem multiple times. Historically the error would have been "already mounted or mount point busy". The error "special device does not exist" can only mean exactly what it says. If the card is in a USB reader, it will be /dev/sd...
by jojopi
Mon Nov 15, 2021 10:18 am
Forum: General discussion
Topic: How can I check fully a device by reading every single file?
Replies: 3
Views: 183

Re: How can I check fully a device by reading every single file?

The closest equivalent to the chkdsk command would be: sudo badblocks -b 4096 -s /dev/mmcblk0p2 There is not much utility to this. Modern drives remap faults internally, and therefore hide them from the operating system. An SD card is just as likely to return the wrong data as admit there is a probl...
by jojopi
Sat Nov 13, 2021 12:17 am
Forum: General discussion
Topic: Request: Please Fix Stylesheet
Replies: 10
Views: 995

Re: Request: Please Fix Stylesheet

I have noticed cases where the effect is inconsistent between different code blocks in the same post. In my recent post https://forums.raspberrypi.com/viewtopic.php?p=1937420#p1937420 the first code block is socially distanced as OP prefers, and the second is snuggled as I think correct. There is no...
by jojopi
Sat Nov 13, 2021 12:06 am
Forum: Troubleshooting
Topic: Bullseye and SFTP Resolved.
Replies: 11
Views: 345

Re: Bullseye and SFTP

Does that mean it's already enabled? No, -Q seems to mean it is supported , which I would call compiled in . The enabled kex algorithms listed under -vv are curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,d...
by jojopi
Fri Nov 12, 2021 9:57 pm
Forum: Troubleshooting
Topic: Bullseye and SFTP Resolved.
Replies: 11
Views: 345

Re: Bullseye and SFTP

OpenSSH adds algorithms all the time. It is one of the main features of SSH protocol2, that it is not tied to any particular encryption, hash, key exchange, compression, etc. Once the new algorithms are well supported, the less secure ones may be deprecated. At least in Debian/Raspbian/RPiOS, the SH...
by jojopi
Mon Nov 01, 2021 7:07 pm
Forum: Assistive technology and accessibility
Topic: Insert key on standard 105 key british keyboard problem.
Replies: 4
Views: 1068

Re: Insert key on standard 105 key british keyboard problem.

The INS key works as expected when used inside an application such as LibreOffice or Mousepad. However when not inside an app, the INS key opens a create new folder dialog on the desktop. The file manager, pcmanfm, is also responsible for the desktop. Input focus will fall back to it whenever no ot...
by jojopi
Mon Nov 01, 2021 12:10 pm
Forum: General discussion
Topic: rpi-imager 'Download for Ubuntu for x86' is not for x86
Replies: 7
Views: 549

Re: rpi-imager 'Download for Ubuntu for x86' is not for x86

Ubuntu does not support (pure) x86-32 any more. Any remaining installs are end of life. Debian still does, but presumably RPT would recommend their version, and then rpi-imager is in the standard repos. (Linux users will not be expecting to find a website binary for their specific distribution, arch...
by jojopi
Sun Oct 31, 2021 10:24 pm
Forum: General discussion
Topic: Raspberry Pi 4 X11 performance
Replies: 11
Views: 690

Re: Raspberry Pi 4 X11 performance

I've been working on an application that uses just X11 the primitives (lines and rectangles) to draw the desired display in the application window. However, I was a bit disappointed to find that it does NOT work on a Raspberry Pi 4 unless I dramatically reduce the number of shapes used by the displ...
by jojopi
Fri Oct 29, 2021 1:00 pm
Forum: General discussion
Topic: Multiple terminals when booting to shell and remote SSH question
Replies: 8
Views: 264

Re: Multiple terminals when booting to shell and remote SSH question

Q1: if I connect to the PiZero via an ssh session on my Mac and launch my weather monitoring app, if I close the ssh session on the Mac will the .py app I launched on the piZero keep running or will it close due to the ssh pipe connection from the Mac closing down? If you launch the program in the ...
by jojopi
Fri Oct 29, 2021 2:10 am
Forum: Beginners
Topic: Looking for a robust and canonical guide to backup Raspberry Pi to NAS
Replies: 10
Views: 386

Re: Looking for a robust and canonical guide to backup Raspberry Pi to NAS

I have never restored my Rasperry Pi using this method, Have you considered how you would restore it? In order to reverse the direction of the rsync, the Pi would have to be running a mostly-working operating system. That means the first step might be to install a fresh image. At this point there i...
by jojopi
Tue Oct 26, 2021 3:38 pm
Forum: SDK
Topic: SOLVED - __aeabi_memset
Replies: 3
Views: 179

Re: __aeabi_memset

The ARM EABI aeabi_memset function has a different signature, to allow aeabi_memclr to tail-chain to it: That is the explanation given in the ARM document IHI0043D_rtabi. It does not make any sense to me. memclr needs to load an extra zero before it falls though to memset. It could just as easily h...
by jojopi
Fri Oct 22, 2021 11:29 am
Forum: Networking and servers
Topic: Mail vulnerabilities
Replies: 11
Views: 566

Re: Mail vulnerabilities

Unfortunately I am definitely incapable of reading it and a fortiori of deducing any action plan. The website connects to your ports and issues the standard commands for "hello" and "what are your capabilities", etc. It publishes your server's responses, and for binary data like...
by jojopi
Thu Oct 21, 2021 9:15 am
Forum: Networking and servers
Topic: Mail vulnerabilities
Replies: 11
Views: 566

Re: Mail vulnerabilities

The site does not report vulnerabilities (at least not for my servers). It just summarizes various information that it can easily grab from the server. That is basically public information already, if you are running your server on the internet. It gives more detail than you included in your first p...

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