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Linux Survival Basics

Read-only, sensitive output

Inspect Certbot Certificate Inventory

You need current certificate names, domains, paths, and expiry from Certbot.

Command

sudo certbot certificates

Before you run this

System impact: Read-only. Output may expose users, paths, tokens, keys, IPs, process arguments, or log details.

When not to use it: Do not delete certificate files from this output alone.

Expected output

Certificate names, domains, expiry dates, and filesystem paths.

System impact

Read-only, sensitive output. Nothing changes. The command reads current state and prints diagnostic evidence.

May require elevated permissions on protected paths or service-owned files.

Recovery / rollback: no state is changed.

When to use it

Use before changing renewal config or deleting old certs.

When not to use it

Do not delete certificate files from this output alone.

Example run

Commands shown

These are the commands shown for inspection. Treat them as an example, not proof that your system will behave identically.

  1. sudo certbot certificates
  2. sudo certbot certificates

next steps

Related commands

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Find the dpkg Lock Owner

Find the process holding the dpkg lock before touching lock files.

sudo lsof /var/lib/dpkg/lock-frontend /var/lib/dpkg/lock 2>/dev/null
Linux Survival Basics Sensitive output

Inspect One Process Open Files

Look at one target process, not the whole host, when pressure is scoped.

sudo lsof -p 1234 | head
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List sudo Group Members

Before granting sudo, see who already has it.

getent group sudo

next diagnostic step

Where to go from this command

Study mapping

Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.

  • LPIC-1 style command-line practice
  • LFCS style performance-task practice
  • Linux+ style troubleshooting review

Independent study support only. No affiliation, endorsement, exam dumps, or real exam questions.