BowerStudios.com

What raid devices available in config:
cat /etc/mdadm/mdadm.conf

Get details on a raid array:
sudo mdadm --detail /dev/md0
sudo mdadm --detail /dev/md/1

What drives are installed:
sudo lsblk -o NAME,FSTYPE,SIZE,MOUNTPOINT,LABEL

What luks devices setup:
sudo dmsetup status

References:

• View available hard drives in Ubuntu
• Setup full disk encryption on a secondary hdd in linux
• Automatically unlock luks encrypted drives with a keyfile

Snapshot from onurguzel.com

Supervisord is a great daemon for managing application processes. However it does not have a reload option, and restart works different than we get used to. These command makes the following effects.
service supervisor restart

Restart supervisor service without making configuration changes available. It stops, and re-starts all managed applications.
supervisorctl restart

Restart application without making configuration changes available. It stops, and re-starts the application.

If you create a new configuration. None of the commands above will make it available. If you want to apply your configuration changes in both existing and new configurations, start applications in new configurations, and re-start all managed applications, you should run:
service supervisor stop
service supervisor start

If you do not want to re-start all managed applications, but make your configuration changes available, use this command:
supervisorctl reread

This command only updates the changes. It does not restart any of the managed applications, even if their configuration has changed. New application configurations cannot be started, neither. (See the “update” command below)
supervisorctl update

Restarts the applications whose configuration has changed.
Note: After the update command, new application configurations becomes available to start, but do not start automatically until the supervisor service restarts or system reboots (even if autostart option is not disabled). In order to start new application, e.g app2, simply use the following command:
supervisorctl start app2

Attach the contents of 1.txt as json to send to a url:
curl --data "@1.txt" -v -H "Content-Type: application/json" https://myapp.com

Grab 10,000 lines after matching, and then look only at the given thread
grep -A 10000 "09:55:.*My API endpoint.*ProviderSearch" myLog.log | grep pool-2-thread-28166

By starting the command with a " " (a space).

From: technovelty.org

From: stackoverflow.com

Wake on Lan

• HiDPI
• change dpi of screen

exclude files from grep

If you're running one of the small instances, try running:
$ top

If kswapd is taking a lot of resources, try running this command:

$ echo 1 > /proc/sys/vm/drop_caches

You'll have to do this as root. Likely, you'll need to reapply it on rebooting.

• Ansible Tricks
• Ansible Filters for Taming Lists