This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.
What this hour is for
A regular expression matches text. The tester runs in the browser on the sample you type. A glob is a different language. The glob tester is the other box. Do not paste a glob into the regex box and call it the same.
Anchors and a character class are enough for one admin question: does this line match the shape I mean. Do not write a pattern whose purpose is to slip past a control. That is not this page.
Do not paste a password to see if it matches. Use a fake sample. 192.0.2.10/24 and example.com are documentation. They stay in the note.
The change you can finish
Apply nothing while you are writing the note. When the lab window opens, it is one change on the host named in the ticket. Read the draft, then the host, then decide.
Rollback is the file, the package version, or the snapshot you saved first. You do not invent a rollback after the only copy is gone.
- Write the shape in a sentence.
- Type a fake sample.
- Draft one pattern.
- Confirm a glob was not used by mistake.
- Reject a pattern whose point is to evade a filter.
- Stop.
Mistakes that outlive the command
Regular Expressions for Sysadmins goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- A glob used as a regex.
- A password pasted as the sample.
- A pattern written to bypass a control.
- An unreadable pattern saved as the standard.
Decisions to write down
One decision for Regular Expressions for Sysadmins: One pattern. The sample is fake. Anchors were considered. The pattern is not an evasion. And the tester did not touch a host.
Checks before you call it done
Confirm this before you call the change done: The sentence is written. The sample matches or the note says it does not. No password was pasted. No host was scanned. And the pattern is short enough to read. If one of those fails, stop.
# One pattern. One fake sample.
# A glob is not a regex.
# Do not write a pattern to evade a filter.Before you leave the host
Regular Expressions for Sysadmins ends when the hostname in the prompt matches the hostname in the ticket. If it does not, you are on the wrong host. Stop. A command that succeeded on the wrong host is not progress.
The draft stays a draft until a person has read the names in it. A generator does not log into the host and does not know which disk is empty. You delete a line that names a host, a path, or an account you did not write down.
192.0.2.10/24, gateway 192.0.2.1, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. example.com is a documentation name. They belong in the note. They are not values you leave on a host because a draft included them.
prompt-for-this is a reminder that a secret is missing. It is not a password, a key, or a token you save in the ticket or in git. The real secret stays in the password store.
One change is the window. If two things move and the result is wrong, you will not know which one did it. The next change waits for its own page.
If the same step fails twice, stop for the day. The failure is the result. Adding a forum command beside a half-applied change produces a host nobody can rebuild. Restore the copy you took first.
A second person reads the hostname and the change aloud. If they cannot find them in the ticket, the note is not done. Silence is not agreement. Then leave the host alone.
This page is a planning guide. It is not a vendor manual, not an official standard, and not permission to touch a host you do not administer. You do not disable a firewall, AppArmor, or SELinux to make a check pass.
Tools for this guide
These tools run in the browser on this site. They do not log into your machines.
Related pillar guides
More in this cluster
The pillar for this page, and the next published pages filed with it.