Some handy CLI tricks I use daily:
Check SSL certificate expiry:
echo | openssl s_client -connect example.com:443 2>/dev/null | openssl x509 -noout -dates
Monitor a webpage for changes:
watch -d -n 300 "curl -s https://example.com/ | md5sum"
Generate a QR code from terminal:
qrencode -t UTF8 "https://your-url.com/"
Quick JSON formatting:
echo "{\"key\":\"value\"}" | python3 -m json.tool
Decode a JWT token:
echo "your.jwt.token" | cut -d. -f2 | base64 -d 2>/dev/null | jq .
If you want these as quick web tools (useful when SSHd into a box without these packages), I threw together a free API toolkit that does all of this over HTTP: JSON formatting, JWT decoding, QR generation, UUID gen, hashing, etc.
What are your go-to one-liners?
Piping nothing into openssl to get it to not keep the connection open is neat.
So, uh, if you’re already using
jq, this should also format JSON:echo "{\"key\":\"value\"}" | jq😅
Ha, you’re absolutely right —
jqalone handles formatting perfectly. I tend to usepython3 -m json.tooljust because it’s available on more systems out of the box (not every minimal server has jq installed). But yeah, if jq is there, it’s the better tool for sure.
