Linux & Administration

Linux presents files through one directory tree beginning at /, but the data underneath that tree can live on different disks, partitions, virtual devices

A Linux username is the human-friendly part of an identity. Underneath it, Linux works with numeric user IDs and group IDs to decide who owns files, which

A web server accepting requests, an SSH session, a database worker, and even a command you run in a terminal all have something fundamental in common

Run uptime or top on a Linux server and you will see three numbers called load average. They might look like 0.42, 0.68, 1.15. At first glance, they look

Run free -h on a busy Linux server and you may see something alarming: most of the RAM appears to be used, while the free column is surprisingly small.

A Linux server is rarely doing just one thing. A web server may be accepting requests, a database may be writing data, scheduled jobs may be running, and

You run uptime and see three numbers: load average: 0.42, 0.58, 0.61 Are they percentages? CPU usage? The number of running processes? And at what point

A Linux server can report very little free memory and still be perfectly healthy. That sounds contradictory, especially if you are used to treating unused

A server reports “No space left on device,” but which filesystem is full, and what is using it? Two Linux commands answer different parts of that question

You remember saving a configuration file, but not its directory. Or you need to identify which files changed during a deployment. The Linux find command