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by DougieLawson
Sun May 26, 2019 8:24 am
Forum: Troubleshooting
Topic: [Solved] Suspicious Network Activity?
Replies: 14
Views: 365

Re: Suspicious Network Activity?

If you write a pcap file with tcpdump you can analyse it with Wireshark on Windows. I use that all the time as it's easier on a headless Raspberry.
by DougieLawson
Sun May 26, 2019 8:17 am
Forum: Troubleshooting
Topic: Raspberry PI 3 B* time problem
Replies: 3
Views: 74

Re: Raspberry PI 3 B* time problem

You can set timezone in the GUI preferences dialog. Or by opening an lxterminal and running sudo raspi-config. It doesn't even need a reboot.
by DougieLawson
Sat May 25, 2019 1:10 pm
Forum: Raspbian
Topic: Audio Distortion using mpg321/123 or aplay
Replies: 12
Views: 177

Re: Audio Distortion using mpg321/123 or aplay

Have you updated to the 4.19.42 kernel (which is now the stock (apt-get) kernel - there's no need for rpi-update)?
by DougieLawson
Sat May 25, 2019 12:54 pm
Forum: General discussion
Topic: number of users that can connect to raspberry 3b
Replies: 30
Views: 749

Re: number of users that can connect to raspberry 3b

I completely understand your use case. You just aren't grasping what I've said. The bottleneck may or may not be in a service on the Raspberry Pi. If it's hostapd (which equally has a RAM requirement for each connected user) which creates a bottleneck then fix that with an external access point. [Cu...
by DougieLawson
Sat May 25, 2019 10:04 am
Forum: Raspbian
Topic: Audio Distortion using mpg321/123 or aplay
Replies: 12
Views: 177

Re: Audio Distortion using mpg321/123 or aplay

TerryC65 wrote:
Sat May 25, 2019 10:00 am
... I tried using 'omxplayer --vol' and 'omxplayer --amp' to change it, but it seems to have no effect.
Try using alsamixer to set the master volume and enjoy the crude terminal graphics.
by DougieLawson
Sat May 25, 2019 9:06 am
Forum: Graphics, sound and multimedia
Topic: Two independent monitors
Replies: 3
Views: 102

Re: Two independent monitors

It can't be done. Use two RPi Zeros.
by DougieLawson
Sat May 25, 2019 8:56 am
Forum: General discussion
Topic: number of users that can connect to raspberry 3b
Replies: 30
Views: 749

Re: number of users that can connect to raspberry 3b

Are you saying that each new wifi connection take so much RAM that after 25 users the RPi freezes? Interesting (I thought myself it could be a wifi driver problem.) I'll try to do some tests to see wether your assertion holds. No, I'm saying you need to measure the base RAM usage when the system is...
by DougieLawson
Fri May 24, 2019 10:20 pm
Forum: General discussion
Topic: number of users that can connect to raspberry 3b
Replies: 30
Views: 749

Re: number of users that can connect to raspberry 3b

Wonder if a fast disk and big swap space on it would let you push the limit up much... In an ideal world you never want your steady state working set to move out to any slow device. Before we could go super sized on mainframes the rule was 67% max. With the other 33% there for the mid-day peaks (in...
by DougieLawson
Fri May 24, 2019 9:59 pm
Forum: General discussion
Topic: number of users that can connect to raspberry 3b
Replies: 30
Views: 749

Re: number of users that can connect to raspberry 3b

Interesting, what do you think is the cause of the limitation? It's 100% guaranteed to be lack of RAM. Each user will take a chunk of RAM on the server. When that pushes your server over the 1GB limit (into swapping hell) you'll reach a practical limit. The big iron I work on for my day job runs ou...
by DougieLawson
Fri May 24, 2019 5:40 pm
Forum: Beginners
Topic: Will adding an external SSD speed up Raspberry Pi?
Replies: 16
Views: 344

Re: Will adding an external SSD speed up Raspberry Pi?

As ever, it depends.

We don't have enough info to tell you on what it depends.

My Raspberries with high speed spinning things run way better; as it's possible to use a spinning thing for swapping.

Haven't got as far as replacing spinning things with solid state thing.
by DougieLawson
Fri May 24, 2019 4:57 pm
Forum: Other projects
Topic: Easy OS installer - closed case
Replies: 9
Views: 233

Re: Easy OS installer

How does this provide anything that isn't already available in NOOBS or the forked NOOBS - PINN?

BTW, you can't boot a fully zipped OS, it's not possible.
by DougieLawson
Fri May 24, 2019 12:17 pm
Forum: Off topic discussion
Topic: [Solved] Pi doubled SanDisk SD card size
Replies: 20
Views: 421

Re: [Solved] Pi doubled SanDisk SD card size

How do you think a reseller can drop the price by £6.50 for a genuine product? If you get cheapo cards you should run a F3 scan before using them for anything important. All of my Raspberries that can boot from USBs are booting from USB sticks. A couple that can't boot from a USB have a bootcode onl...
by DougieLawson
Fri May 24, 2019 10:51 am
Forum: Off topic discussion
Topic: [Solved] Pi doubled SanDisk SD card size
Replies: 20
Views: 421

Re: [Solved] Pi doubled SanDisk SD card size

I think you're missing the obvious answer; that an Amazon reseller sold you a fake card. That happens all the time and is the reason I buy cards from Sainsburys/Argos, Tesco or Morrisons (mobile phone depts) and keep the receipt.
by DougieLawson
Fri May 24, 2019 10:13 am
Forum: Beginners
Topic: No module named flask after installing flask
Replies: 14
Views: 204

Re: No module named flask after installing flask

Your original errors have python3 written all over it. Stop using python2 for new code. Write everything new with python3.
by DougieLawson
Fri May 24, 2019 10:03 am
Forum: Beginners
Topic: No module named flask after installing flask
Replies: 14
Views: 204

Re: No module named flask after installing flask

You've installed flask for python2 you need to use sudo pip3 install ... to get it for python3 (and all users).
by DougieLawson
Fri May 24, 2019 9:51 am
Forum: Networking and servers
Topic: Letsencrypt error on checking for new certificate
Replies: 3
Views: 82

Re: Letsencrypt error on checking for new certificate

Just edit /usr/bin/certbot-auto to replace pycparser==2.19 \ --hash=sha256:a988718abfad80b6b157acce7bf130a30876d27603738ac39f140993246b25b3 with pycparser==2.19 \ --hash=sha256:a988718abfad80b6b157acce7bf130a30876d27603738ac39f140993246b25b3 \ --hash=sha256:344870c533812cb119c5475b5aed033ec546118711...
by DougieLawson
Fri May 24, 2019 9:02 am
Forum: Python
Topic: 'bool' object is not callable
Replies: 1
Views: 70

Re: 'bool' object is not callable

True is a boolean constant. It doesn't have any methods. So your

Code: Select all

shell=True(image_path,'rb')
is a syntax error. You've probably got that opening parenthesis in the wrong place.
by DougieLawson
Thu May 23, 2019 9:36 pm
Forum: Troubleshooting
Topic: hostapd broken after rpi-update.
Replies: 3
Views: 97

Re: hostapd broken after rpi-update.

You don't need rpi-update this week. Nine days ago the 4.19.42 rpi-update was pushed to the main apt repos. The stock stable kernel should work with your broken USB device.
by DougieLawson
Thu May 23, 2019 9:33 pm
Forum: Troubleshooting
Topic: Unable to restart isc-dhcp-server
Replies: 4
Views: 66

Re: Unable to restart isc-dhcp-server

What's the junk line at the top of the file?

If you want commentary lines start them with a # (hash) symbol.
by DougieLawson
Thu May 23, 2019 8:28 pm
Forum: Troubleshooting
Topic: Unable to restart isc-dhcp-server
Replies: 4
Views: 66

Re: Unable to restart isc-dhcp-server

Your error messages seem to point to a syntax error in your dhcpd.conf file. You should probably cut'n'paste it on here - if you can't see the error.
by DougieLawson
Thu May 23, 2019 5:11 pm
Forum: Automation, sensing and robotics
Topic: Checking when food/water bowls are empty?
Replies: 14
Views: 287

Re: Checking when food/water bowls are empty?

Thank you - the QR Code sounds like a good idea because I’m such a noob to Raspberry Pi! I’ll investigate trying to make my own QR Codes. There's some clues to mucking about with QRs in https://www.raspberrypi.org/magpi/issues/27/ Can't help with the scanning. But you should be able to do that with...
by DougieLawson
Thu May 23, 2019 5:07 pm
Forum: Camera board
Topic: RPI-CAM2 and RPI-CAM2 NoIR defect
Replies: 6
Views: 287

Re: RPI-CAM2 and RPI-CAM2 NoIR defect

Have you swapped out the ribbon cable for a known good one?
by DougieLawson
Thu May 23, 2019 9:16 am
Forum: Beginners
Topic: using rasberry pi for diiffrent tasks at the same time
Replies: 4
Views: 139

Re: using rasberry pi for diiffrent tasks at the same time

Gavinmc42 wrote:
Thu May 23, 2019 5:59 am
Doing 4 things at once can be 10 times harder than doing 4 things separately.
Pat head, rub tummy for Pi's?
One RPi3B+ four python scripts - that's four tasks running at once.

You could do it in a single script with python threading.

No tummy rubbing needed.
by DougieLawson
Wed May 22, 2019 11:03 pm
Forum: Troubleshooting
Topic: Error, INIT: Id "S0" respawning too fast: disabled for 5 minutes
Replies: 3
Views: 93

Re: Error, INIT: Id "S0" respawning too fast: disabled for 5 minutes

You won't get support for systems running non-standard OSes on here, the folks that volunteer on here don't have time to muck about with things that aren't built on Raspbian. Sysvinit respawning usually points to a root filesystem that needs a fsck as it's been corrupted by failing to shut down in a...

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