tag: #tip-of-the-week

A nightly pg_dump at 4am means that when prod dies at 3pm you lose eleven hours of data, and there is nothing you can do about it. Postgres already writes down every change as it happens in the WAL. Archive that continuously on top of a base backup and you can recover to any second, including the moment right before someone ran the bad command. That is PITR, and it is the difference between an outage and a catastrophe. With the two numbers, RPO and RTO, that should drive the whole decision.

Plain ip link and ip addr dump a wall of text for every interface, most of it irrelevant when you just want to know what is up and what has an address. The -br flag collapses each interface to a single line, and it is the version you should be reaching for on every troubleshooting call.

On Debian and Ubuntu, two commands look like they do the same thing. They do not. adduser is a Perl wrapper from the adduser package. useradd is the raw binary from upstream shadow-utils. The difference catches operators who write portable scripts and expect either name to work the same way on RHEL or Alpine.

PID 1 in Linux has special responsibilities that most application processes are not designed to handle. The --init flag in Docker inserts a tiny init process between PID 1 and your application, which solves the zombie reaping problem and the signal forwarding problem in one line.

The bash !$ history expansion substitutes the last argument of the previous command which turns destructive operations like rm into a two-step ritual where the first step is always a preview.