Interview Q&A / Linux & Shell
Linux & Shell interview questions
Permissions, processes, pipes and the commands you are expected to know cold.
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- How do you see which ports are listening and which process owns them?
Run sudo ss -tulpn. It lists TCP and UDP listening sockets with numeric ports and the owning process name and PID. ss has replaced the older netstat on modern Linux, and you can filter with grep or an expression like sport = :8080.
BeginnerQuick answer1 min read - How do you send GET and POST requests with curl?
curl URL sends a GET. For a POST with JSON use curl -X POST -H 'Content-Type: application/json' -d '{...}' URL. Adding -d already makes the request a POST, and -i or -v shows the response headers.
BeginnerQuick answer1 min read - How does SSH key-based login work, and how do you set it up?
You generate a key pair with ssh-keygen, keep the private key on your machine and copy the public key to the server's ~/.ssh/authorized_keys with ssh-copy-id. The server then challenges you to prove you hold the private key, so no password crosses the network.
BeginnerQuick answer1 min read