To get crazy fast in the command line, try Command Line Challenge, practicelinux.com, learnshell.org and commandlinefu.com. Source: 8 months ago

I put something together very similar to this, https://cmdchallenge.com that I like a bit better because it has console input. There is also a Christmas edition "12 days of shell" https://12days.cmdchallenge.com that is more like a learning progression. - Source: Hacker News / 8 months ago

Nice to see this posted on HN! A while back ago I used them for the design of a site a built https://cmdchallenge.com/ which gives it a nice feel of achievement badges without using standard unicode characters that may look different depending on the client. - Source: Hacker News / 9 months ago

Cmd challenge is a website that gives you a linux terminal, and asks you to perform different tasks on it, so you sharpen your linux terminal skills. - Source: dev.to / over 1 year ago

Aye that's a good one. CmdChallenge is also quite nice. Source: almost 2 years ago

Chat with launchpass.com live chat and ask them, if this doesn't help you. Come back to me via DM. Source: about 2 years ago

Chat to the live support on https://launchpass.com/. Source: about 2 years ago

Many paid communities are built on Slack. Check out https://launchpass.com/. Source: over 3 years ago