06_Terminal — seeing and making bytes without a language

Level: 101 → 201 · for anyone with a terminal

xxd and od were taught in chapter 1 because nothing later works without them. This chapter is the rest of the toolbox: putting known bytes on a pipe, the last byte of a text file and everything that depends on it, reading a dump's other columns without being lied to, re-encoding a file, the locale that silently sets every tool's default, the tool that guesses, the bytes at offset 0 that decide whether a file runs at all, why binary is a reader's verdict and not something a file is, and the syscall that tells a program whether anyone is watching.

#	Lesson	The question it answers	Status
1	printf writes bytes	How do I put exactly the bytes I mean in front of xxd?	written
2	The trailing newline	Why did cat print nothing for a file that is not empty?	written
3	A character and its bytes on one line	How do I see the letter and its hex at the same time?	written
4	Inspecting a file	Which column of a dump is the file, and which ones are the tool guessing?	written
5	iconv	How do I re-encode a file, and what does its refusal mean?	written
6	Locale and LC_CTYPE	What is the terminal's default encoding, and which tools change with it?	written
7	file guesses	Why is file's answer an inference, and when is it sure?	written
8	File type is four questions	Who decides what kind of file this is, and why do they disagree?	written
9	The first two bytes	Why does my script say /bin/sh is missing when it is right there?	written
10	Binary is a verdict, not a property	I named it .bin, so why do file and git call it text?	written
11	Terminal hyperlinks, and the URI that is not one	What is in a clickable filename, and what did it do to the accent?	written
12	A pipe is not a terminal	Why did piping my program into cat change what it printed?	written