Web / NGINX Interview questions
How do you troubleshoot NGINX configuration errors before reloading?
sudo nginx -t
This command parses the full configuration tree - including all included files - and reports the exact file and line number of any syntax error, along with a final "syntax is ok / test is successful" message if everything checks out. It catches missing semicolons, unmatched braces, and unknown directives, but it doesn't catch logical mistakes like a proxy_pass pointing at the wrong port.
Only after nginx -t passes should you run systemctl reload nginx or nginx -s reload. Skipping this step is a common cause of accidental downtime, since a reload with broken configuration can leave the master process refusing to apply changes, or in worse cases affect the running workers.
Which command validates NGINX configuration syntax without applying it?
Does nginx -t catch a proxy_pass pointing at the wrong backend port?
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