bash params
${A} == $A
${A:-$B} .. if no A, use $B
${A:?error message} .. if no A, error
${#A} .. length of A
${A#pattern} remove prefix pattern
${A%pattern} remove suffix pattern
${A/before/after} substitution (once)
${A//before/after} substitution (global)
${A:offset:length} substring


sort nginx logs by most accessed URLs
awk -F\" '{print $2}' access.log | awk '{print $2}' | sort | uniq -c | sort -gr


https://magic.link/
magic links delivered via email for logins


VS Code extension development

See https://github.com/goessner/microjam for example


Excellent story about Atari game
https://arxiv.org/pdf/1811.02035.pdf