This post appeared originally in our sysadvent series and has been moved here following the discontinuation of the sysadvent microsite
pv is a nice little tool that will take stdin and make a nice little
progress bar and displaying time elapsed, percentage completed (if size is known)
current throughput rate and the total data transferred and with an ETA.
So if you have a tool that can output it’s result on standard output or read from standard input, one can get a progress bar!
It’s nice to know that “data is flowing”.
Other examples
Send file with Netcat and get a nice progress-bar:
pv file | nc -w 1 example.com 3000
Get progress bar on tar output:
tar zcf - /directory | pv > backup.tar.gz
MySQL dump/restore:
mysqldump database | pv > database.sql
pv database.sql | mysql database
Limit the transfer rate and size of data over a pipe
cat /dev/zero | pv -L 3m -Ss 100m > /dev/null
Putting Varnish CDN in front of a serverless container with OpenTofu
Serverless containers are a great way to run a small site: you push an image, you get an HTTPS URL, and you don’t pay for resources when nobody is accessing your application. What you don’t get is caching close to the client, or protection from the cold-start penalty every time a visitor arrives after the serverless container has spun down.
That is exactly what a CDN is for and an excellent choice for this is Varnish CDN which lets you ... [continue reading]