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2025-04-30
Finding the commit that broke it with git bisect
A binary search over a few hundred commits takes about eight tests.
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2025-04-23
Where cron output goes
It is mailed to the owner — and silently dropped without an MTA.
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2025-04-16
Disk quotas so one account cannot fill the machine
Mount options, initialization, then limits.
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2025-04-09
Keep log timestamps in UTC
Local time plus daylight saving is how you lose an hour during an incident.
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2025-04-02
Rotating TLS session ticket keys
A key that never rotates is a long-lived key to recorded traffic.
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2025-03-26
CNAME and MX cannot coexist, and mail breaks when they try
An apex CNAME removes the MX records.
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2025-03-19
Holding package versions against automatic upgrades
hold, pinning, and excluding packages from unattended-upgrades.
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2025-03-12
TCP parameters worth tuning, and ones to leave alone
Backlogs and tw_reuse yes; rmem defaults no.
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2025-03-05
The full sequence for extending LVM
PV, VG, LV, filesystem — all four layers.
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2025-02-26
After a tzdata update, timestamps disagree
Timezone rules change, and container and host versions drift apart.
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2025-02-19
curl has four timeouts; do not set just one
Connect, overall, and speed-based limits do different jobs.
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2025-02-12
HSTS preload is easy to submit and hard to undo
It ships inside browsers, and removal waits for the next release.