prasanthj

Mount Separately
----------------
# mount nvme SSDs to /dataN when available for specific instance types
# There are only 4 nvme slots in r5 instances. /dev/nvme0n1 is root EBS volume.
for i in $(seq 1 4); do
  if [ -e "/dev/nvme${i}n1" ]
  then
    echo "Mounting /dev/nvme${i}n1 to /data${i}"
    sudo mkfs.ext4 -E nodiscard /dev/nvme${i}n1
    sudo mkdir -p /data${i}

prasanthj

-- hot reload init.lua script
function reloadConfig(files)
    doReload = false
    for _,file in pairs(files) do
        if file:sub(-4) == ".lua" then
            doReload = true
        end
    end
    if doReload then
        hs.reload()

prasanthj

Enable native memory tracking in JVM by specifying the following flag

-XX:NativeMemoryTracking=detail

Know the <PID> of the java process

jps

To print ps based RSS

ps -p <PID> -o pcpu,rss,size,vsize

To print native memory tracking summary

prasanthj

Notes to make IR shield (made by LinkSprite) work in Raspberry Pi 3 (bought from Amazon [1]). 
The vendor has some documentation [2] but that is not complete and sufficient for Raspbian Stretch. 
Following are the changes that I made to make it work.

$ sudo apt-get update
$ sudo apt-get install lirc

# Add the following lines to /etc/modules file
lirc_dev
lirc_rpi gpio_in_pin=18 gpio_out_pin=17

prasanthj

# PDSH Usage
export PDSH_SSH_ARGS_APPEND="-q -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -i ~/.ssh/private.key"
pdsh -R ssh -w ^slaves.txt

# parallel-ssh Usage
parallel-ssh -x "-oStrictHostKeyChecking=no -i ~/.ssh/private.key" -i -h slaves.txt "sudo -u root jps | grep "LlapDaemon" | cut -f1 -d' '"

# remote heap-dump
# Add the following contents to jcmds.sh and use parallel-scp to copy the script to all hosts
#!/bin/bash

prasanthj

{{ $all := . }}
{{ $servers := .Servers }}
{{ $cfg := .Cfg }}
{{ $IsIPV6Enabled := .IsIPV6Enabled }}
{{ $healthzURI := .HealthzURI }}
{{ $backends := .Backends }}
{{ $proxyHeaders := .ProxySetHeaders }}
{{ $addHeaders := .AddHeaders }}

# Configuration checksum: {{ $all.Cfg.Checksum }}

prasanthj

chrome.tabs.query({'active': true, 'lastFocusedWindow': true, 'currentWindow': true}, function (tabs) {
    var url = tabs[0].url;
    console.log(url);
});

prasanthj

apt-get update
apt-get install -y python curl vim
curl -O https://bootstrap.pypa.io/get-pip.py
export PATH=~/.local/bin:$PATH
python get-pip.py --user
pip install awscli --upgrade --user

mkdir -p ~/.aws
vim ~/.aws/config
[default]

prasanthj

set vpn_name to "'VPN_NAME'"

tell application "System Events"
	set rc to do shell script "scutil --nc status " & vpn_name
	if rc starts with "Connected" then
		do shell script "scutil --nc stop " & vpn_name
	else
		-- get current clipboard contents as a string
		set CurrentClipboard to the clipboard as string
		

prasanthj

Download Eclipse MAT from https://www.eclipse.org/mat/

Change Xmx depending on heap dump size being analyzed in ini file. If GC errors are observed then add -XX:-UseGCOverheadLimit option too

vim ~/home/pkgs/mat/MemoryAnalyzer.ini
~/home/pkgs/mat/ParseHeapDump.sh heapdump.hprof