Somajit SomajitDey

List of freemium port-forwarding services

Useful for accessing a computer that does not have a public IP address, over the internet. The machine can be behind multiple firewalls and NATs.

ngrok how to (tested with Linux and WSL)

./ngrok authtoken

How to use streambin for event-based workflow : pubsub (publish/subscribe) model

Push based workflow is more efficient than repeated pulls (polling). Thankfully, there is currently a free service for the same which is easy to use : https://streambin.pbedat.de/. There is also emitter.io and free, public MQTT brokers such as broker.hivemq.com (list).

Create a unique channel-key - it may be the hash of your email id or the hash of your MAC address, or may even be the fingerprint of freshly generated private-public keypair.

url="https://streambin.pbedat.de/streams/${channel_key}"

Updating a Gist or file using API is much faster (almost 3 times) than git-push

Git-push takes a lot of work figuring out what files need to be pushed. The local copy also needs to query upstream about its current state before it can decide whether a pull is necessary before push.

A local commit, on the other hand, takes almost no work compared to git-push.

Because Gist / file update using the REST API is nothing but a file-ransfer over https + a local commit@upstream, it is supposed to be faster than git-push.

Git-fetch is faster than git-push and is also better than download using API

Server-side

Create free ephemeral http relay using localhost.run:

port=<port> # Choose your local port that your server will listen to
file=<filename> # Choose file where <subdomain.localhost.run> will be stored

# Create tunnel in background
ssh -n -R 80:localhost:$port [email protected] -- --output json --no-inject-http-proxy-headers --no-inject-proxy-protocol-header 2>/dev/null | jq --unbuffered -r '.address' > ${file} &

  key=<random but unique key> # Such as the hash of your email id!
  
  ########### Server:
  
  mkfifo pipe
  
  bash --rcfile <(echo 'PS0="$(tput cuu1; tput ed)"') -i <pipe |&
  curl -sf -N -T . https://pipeto.me/${key} >pipe

chroot #### Jail :> Confine a command's access within given root directory
runuser #### Run command as another user. Compare su
stdbuf [-oL] command #### Line buffering in output
rlwrap [-cr -aPassword: -p -S -P -o] command #### GNU Readline + History + TAB-Autocompletion + Colored prompt + Password hiding
fold #### Pretty line wrapping
wrap #### Pretty line wrapping
pr ### Paginate text file - prettify
more
less
tty ### Print the file name of the terminal connected to standard input

	# First run the following 2 lines in your interactive bash attached to a controlling terminal
	export bashpidfile="/tmp/bashpid" # File that stores the bash pid
	export PROMPT_COMMAND='echo $$ > $bashpidfile' # Or, replace $$ with $BASHPID

	# From another terminal do the following
	### TPGID gives fg proc group on the tty the process is connected to, or -1 if the process is not connected to a tty
	fgpg=$(ps --pid $(awk NR==1 $bashpidfile) -o tpgid=)

	# Send signal SIG to all foreground processes to emulate user Ctrl- inputs
	# Ctrl-C: INT, Ctrl-Z: TSTP, Ctrl-\: QUIT

	### Source me
	readline_cword(){
	# Gives current word of Bash readline, viz. the word where the insertion point/cursor is currently at
	set -- ${READLINE_LINE}
	local length=${#1}
	while ((length < READLINE_POINT)); do
	shift
	length+=${#1}
	done
	echo -n "${1}"