Development

• cheat.sh: accessible via curl or a browser.
• cheatsheets.zip
• Free for dev: online tools with free tiers.
• edX: introduction to Linux

Regex

• Regex 101
• Regexr
• Regex tester

C/C++

• Compiler explorer: assembly for a C/C++ code snippet.
• Quick C++ benchmarks

Shell programming

• awesome-shell
• Shell check
• Explain shell
• Learn Bash in Y minutes
• Ryan’s Tutorial