On bash, run –
sudo systemd-resolve --flush-caches
Should be done.
Change the datacenter set in cassandra-rackdc on Ubuntu
Problem: Changing just the datacenter name in cassandra-rackdc.properties gives the error:
Cannot start node if snitch's data center [newName] differs from previous data center [oldName]. Please fix the snitch configuration, decommission and rebootstrap this node or use the flag -Dcassandra.ignore_dc=true.Solution:
If you are just beginning to setup you cassandra cluster, and is ok to reset the data to bootstrapped state, do this
sudo service cassandra stop sudo rm -R /var/lib/cassandra sudo mkdir /var/lib/cassandra sudo chown cassandra /var/lib/cassandra sudo service cassandra start
If you need to persist the existing data, do this
sudo vi /etc/cassandra/cassandra-env.sh
# edit the JVM_OPTS line to make it look like below
JVM_OPTS=\"$JVM_OPTS -Dcassandra.ignore_rack=true -Dcassandra.ignore_dc=true\"
sudo service cassandra restart
This should normally resolve the dc name correction in rack-dc properties file.
RabbitMQ installation fails in in the last leg of setting up in ubuntu 20.04
Error:
Setting up rabbitmq-server (3.8.16-1) … Job for rabbitmq-server.service failed because the control process exited with error code. See "systemctl status rabbitmq-server.service" and "journalctl -xe" for details. invoke-rc.d: initscript rabbitmq-server, action "start" failed.
Reason: libtinfo.so library missing.
Solution:
sudo apt install libncurses5
Note: No need to reattempt the installation.
An “eat dosa!” reminder for busy kids :)
Here is a one hour HTML app that you can use to repeat recorded audio to remind your busy kids they have to finish that food on the table, while watching their favorite videos on YouTube.
To use the app is this simple –
- Click on record button. Give permission to access microphone if it asks for it.
- The recording automatically stops in 4 seconds and replays what it recorded. You can re-record till you are satisfied with the playback.
- Now you can set the number of seconds of interval, between which the above audio has to be repeated.
- Click on “Start Reminder” button to start the reminders.
- When your kid is done eating, you can stop the reminders by clicking “Stop Reminder” button
Happy parenting !
Enable dark mode for Chrome on desktop
Dark mode is great to protect your eyes, more so if you are a coder.
Here is how you can apply dark more on chrome on your desktop –
- In the address bar paste this address : chrome://flags/#enable-force-dark
- Change the setting “Force Dark Mode for Web Contents” from default to “enabled”
That’s it. Now you can have easy on eyes theme on Chrome, just like your IDE !
NPM install gives error : Cannot find module ‘semver’
Problem:
We get this error when we do npm install –
Error: Cannot find module ‘semver’
Require stack:
- /usr/share/npm/lib/utils/unsupported.js
- /usr/share/npm/bin/npm-cli.js
at Function.Module._resolveFilename (node:internal/modules/cjs/loader:924:15)
at Function.Module._load (node:internal/modules/cjs/loader:769:27)
at Module.require (node:internal/modules/cjs/loader:996:19)
at require (node:internal/modules/cjs/helpers:92:18)
at Object. (/usr/share/npm/lib/utils/unsupported.js:2:14)
Reason:
Version issues
Fix:
Run these commands
sudo rm -rf /usr/local/bin/npm /usr/local/share/man/man1/node* ~/.npm sudo rm -rf /usr/local/lib/node* sudo rm -rf /usr/local/bin/node* sudo rm -rf /usr/local/include/node* sudo apt-get purge nodejs npm sudo apt autoremove sudo apt-get install nodejs npm
Try now. Should be fixed !
Fix : Docker node down after restart
Problem: One of the docker nodes does not start up after restart. Error in the log is
Reason: Docker swarm and network stack sucks.
Fix:
IP Telephony – bit rates of audio formats, and other notes
The bit rates for the most common audio formats –
| ALAW | 8 BITS |
| ULAW | 8 BITS |
| PCM | 16 BITS SIGNED/UNSIGNED |
| ADPCM | 8 BITS |
The endian-ness for more than one byte systems:
| Motorola Processors | Big Endian |
| Intel Processors | Small Endian |
Fix: Cannot start container Subnet sandbox join failed error from docker
Error : Few docker containers don’t start up. In the /var/log/syslog they give the error “Cannot start container Subnet sandbox join failed…”
Fix: Restart the machine !
Optionally you can try the steps mentioned here, and see that they don’t work, and restart the machine anyway 🙂
React Ajax call on load gives : “Error: Should not already be working.”
Problem : On page refreshes, the ajax calls in the componentDidMount functions throws the error : “Error: Should not already be working.”
Reason : Probably the ajax request is called before the react’s async calls framework is initialized.
Fix: Run within a timeout function
Eg –
componentDidMount() {
setTimeout(() => {
$.ajax(...);
}, 400);
}