The Life of a Block Device: Seven Names for One Disk, and Not One of Them Is Both Stable and Unique
Every name a Linux disk has is either a value stored inside it, and so copied by anything that copies the disk, or a description of the slot it is…
The Life of a Scheduled Job: Eight Stages, and the Failure You Should Fear Exits Zero
A scheduled job is the only routine thing on a Linux machine that destroys the evidence it ran by succeeding. Eight stages between the line you wrote and the person…
The Life of a Log Line: Every Field Has an Author, and the Record Does Not Say Who
The standard way to answer “who logged in as root” is one of three commands: journalctl -t sshd, journalctl _COMM=sshd, or journalctl -u ssh. They are taught interchangeably. Here is…
How Time Works on a Linux Machine: When the Clock Moves, Nothing Writes It Down
Stage 1: The clock nobody is keeping Run the hinge here, and then run the tool that is supposed to read what it finds: Three device paths, tried in order,…
What Ships in Your Container Image, and What Happens to It After You Push
Stage 1: The build context, and what got in that you did not put there The build starts by sending a directory to the builder. Not the files your Dockerfile…
The Life of a System Call: Who Actually Answered
Here is a small program. It opens a file, forks, waits for the child, asks its own PID and exits — five library calls, and I wrote every one of…
The Life of a Unix Socket
Seven stages, from an object with no name to a name with no object. Why every diagnostic tool on the machine prints a path it never checked, why only the…
How a Path Becomes a File
Path resolution is not a function from strings to strings. The six stages between a pathname and an open file: the trailing slash that defeats O_NOFOLLOW, why .. is a…
The Life of a File Descriptor: Seven Stages from open() to close()
A file descriptor is a small non-negative integer, and almost everything difficult about Linux plumbing comes from one fact about it: the number is yours, and the thing it points…
The Life of a Package: Eight Stages Between apt install and Working Software
You type apt install nginx, watch some text scroll past, and have a web server. Between those two moments sit eight stages, two entirely different trust models, and one asymmetry…