What Is a Linux Namespace?

A Linux namespace is a kernel feature that partitions a global resource so that processes inside the namespace see only their own isolated instance of it. Separate namespaces exist for process IDs, mounts, networking, users, and more. Combining several namespaces is what gives a container the illusion of its own private machine.

Why it matters

Namespaces are the core of how CI jobs run isolated in containers, with their own process tree and network. Knowing which namespaces are in play explains why a process inside a container cannot see ones outside it.

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