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Reposted by Julia Evans

Daniel Pipkin 🦥

@danielpipk.in

I'm trying to get more comfortable with C. @b0rk.jvns.ca's Memory Spy tool has really strengthened my intuition for the bits behind the variables.
memory-spy.wizardzines.com

Screenshot of memory spy website showing why negative one equals 65535 because they are both 1 away from zero.

November 3, 2025 at 3:04 AM

Julia Evans

@b0rk.jvns.ca

just added the MEGA TERMINAL CHEAT SHEET from "The Secret Rules of the Terminal" to our list of posters at wizardzines.com#posters

October 20, 2025 at 3:22 PM

Julia Evans

@b0rk.jvns.ca

TERM

wizardzines.com/comics/term/

(from The Secret Rules of the Terminal, out now! wizardzines.com/zines/terminal)

different terminal emulators use different escape codes

terminal emulator 1: if you print out ESC[2J I’ll clear the screen!

terminal emulator 2: for me it’s ESC[HESC[J!
your system has a database called “terminfo” with escape codes in it

how if plays out when you press Ctrl+L to clear the screen:

program, with a little heart over it, thinking:
ah, she wants fo clear the screen! I’ll look up how to do that in the terminfo database…

(on my machine, the database is in /usr/share/terminfo)

program: ESC[HESC[J

terminal emulator, thinking: ok, clearing the screen!
how programs know what terminal you’re using: TERM

your terminal emulator sets the TERM environment variable when it starts

fun fact: terminal emulators often say they’re “xterm-256color” even if they’re not
this can break when SSHing into an old system with a new terminal emulator

(in a VERY annoying way)

happy little stick fiture: I am using ghostty

program, with a little heart over it: NOPE never heard of it
some ways to fix TERM

install the terminfo file for your terminal emulator on the system
use a different terminal emulator
just set TERM=xterm-256color, it’ll often sort of work

October 14, 2025 at 3:08 PM

Julia Evans

@b0rk.jvns.ca

notes on switching to Helix from vim jvns.ca/blog/2025/10...

October 10, 2025 at 2:25 PM

Julia Evans

@b0rk.jvns.ca

watching this was such a fun way to learn a little about Ethernet

TracketPacer @tracketpacer.bsky.social · Oct 9

what happens if u cut 4 wires out of an ethernet cable & then plug it into yr PC

October 9, 2025 at 2:32 PM

Julia Evans

@b0rk.jvns.ca

redirects

wizardzines.com/comics/termi...

(from "The Secret Rules of the Terminal", out now! wizardzines.com/zines/termin...)

redirect to a file:

cmd > file.txt terminal emulator into program, program out to file.txt, error out to terminal emulator
append to a file:

cmd >> file.txt terminal emulator into program, program out to file.txt (append mode), error out to terminal emulator
send a file to stdin:

cmd < file.txt file.txt into program, program out and err to terminal emulator
redirect stderr to a file:

cmd 2 > file.txt terminal emulator into program, program out to nowhere, err out to file.txt
redirect stdout AND stderr:

cmd > file.txt 2>&1 terminal emulator into program, out and err to file.txt
pipe stdout:

cmd1 | cmd2 terminal emulator into program 1, 1 out to program 2 via pipe, 2 out to command line, program 2 out 1 and 2 to terminal emulator
pipe stdout AND stderr:

cmd1 2>&1 | cmd2 terminal emulator into program 1, 1 and 2 out to program 2 via pipe, program 2 out 1 and 2 to terminal emulator
three gotchas

cmd file.txt > file.txt will delete the contents of file.txt some people use set -o noclobber (in bash/zsh) to avoid this

but I just have “never read from redirect to the same file” seared into my memory.

sudo echo blah > /root/file.txt doesn’t write to /root/file.txt as root. Instead, do:

echo blah | sudo tee /root/file.txt or sudo sh -c 'echo blah > /root/file.txt'

cmd 2>&1 > file.txt doesn’t write both stdout and stderr to file.txt. Instead, do: cmd > file.txt 2>&1

cat vs <

I almost always prefer to do:

cat file.txt | cmd

instead of

cmd < file.txt

it works fine & it feels better to me

using cat can be slower if if’s a GIANT file though
&> and &|

some shells support &> and &| to redirect/pipe both stdout and stderr

(also some shells use |& instead of &|)

October 7, 2025 at 3:03 PM

Julia Evans

@b0rk.jvns.ca

meet the terminal emulator wizardzines.com/comics/meet-...

(from The Secret Rules of the Terminal, out now! (wizardzines.com/zines/termin...)

your terminal emulator has two main jobs

turn your actions (typing & clicking) into bytes and send them
receive bytes and display them visually

Illustration of a terminal emulator, with a winking cursor face, and a program, represented by a box with a smiley face. The program has a heart above it, and there are arrows going back and forth between them labelled “bytes”
a little bit of history

it’s called an “emulator” because in the 80s a “terminal” was a separate machine from the computer

Illustration of a bulky old monitor, with a keyboard attached with a spiral cord, and a wire running to a panl of buttons and displays, labelld “mainframe”. There are arrows going back and forth between them labelled “bytes”

We still use the same 80s protocol!
what are these “bytes”?

the bytes are either:

text (like cat blah.txt)
escape codes (for example to tell the terminal what colour to display the text in)
control characters example Ctrl+C is the byte 3)

it’s in charge of copy and paste

your terminal emulator lets you select text and copy/paste it (usually with Ctrl+Shift+C (Linux) or Cmd+C (Mac))

(copy & paste tips on page 18!)
it manages colours and fonts!

some terminal emulators come with a big theme library of different colourschemes!

if yours doesn’t, this site has colourschemes for many terminal emulators: iterm2colorschemes.com
fun fact: how Ctrl-X gets translated to bytes

Ctrl-A => 1
Ctrl-B => 2
...
Ctrl-Z => 26

Ctrl is the only modifier key I trust in the terminal, all of the others can work differently depending on the situation

September 29, 2025 at 3:03 PM

Julia Evans

@b0rk.jvns.ca

stty

wizardzines.com/comics/stty/

(from The Secret Rules of the Terminal, out now! wizardzines.com/zines/termin...)

your TTY driver has configuration

you can see how it’s configured by running:

stty -a

for example it print out the current window size!
Ctrl+S

by default, pressing Ctrl+S wi(( freeze your terminal (and Ctrl+Q wi(( unfreeze) I have never wanted this in my life, you can turn it off with stty -ixon (fish turns it off by default)

###fun fact: changing Ctrl+C technically you can use stty to set a different keyboard shortcut for Ctrl+C, (ike “u”

stty intr u

this is extremely chaotic and I can’t imagine a reason that I would ever do this though
programs have to configure the TTY driver to get friendly features

developer: I want arrow keys to work in my program!

other person: better tell the TTY driver to turn off canonical mode! (more on the next page)
the TTY driver’s settings are called “termios settings”

for the gnarly details:

man termios

but if you’re writing a terminal program libraries like readline or ncurses will handle setting up the TTY driver
panel 6

smiling stick figure with short curly hair: I’ve only needed to use stty once in the last 20 years and I mostly don’t understand its output but I think it’s a fun view into terminal internals!

September 24, 2025 at 3:21 PM

Julia Evans

@b0rk.jvns.ca

added a cheat sheet to the official Git website

(with a lot of help from other folks who work on the website)

git-scm.com/cheat-sheet

Git Cheat Sheet

git-scm.com

September 16, 2025 at 6:28 PM

Julia Evans

@b0rk.jvns.ca

TERM

wizardzines.com/comics/term/

(from "The Secret Rules of the Terminal", out now! wizardzines.com/zines/termin...)

September 15, 2025 at 3:06 PM

Julia Evans

@b0rk.jvns.ca

finally (after literally everyone else *) I got my print copy of The Secret Rules of the Terminal!

wizardzines.com/zines/termin...

(* or I hope after literally everyone else, please send us a support email if you didn't get your preordered copy yet!)

The Secret Rules of the Terminal, by Julia Evans - The cover illustration depicts three people doing arcane terminal magic in a temple with a smoking censer in the background. Each of the three people has curly brown hair and light brown skin. They are all wearing dresses, billowing cloaks, and utility belts with keyboard symbols on them. The one on the left holds a palette of paints and a brush. The one on the right has a staff with a $ symbol on it and a starfish at the top. The one in the centre has a sword and is reading from a book whose cover says “>_” and “./”, which rests on a lectern with a smiling snake wrapped around it.

September 8, 2025 at 3:13 PM

Julia Evans

@b0rk.jvns.ca

meet the TTY driver

wizardzines.com/comics/meet-...

(from "The Secret Rules of the Terminal", out now!)

the TTY driver is the most obscure part of the system

You almost never need to think about it, but when I’ve wanted to do something weird (like put a terminal in a web browser) understanding the driver is SO USEFUL
when you start your terminal emulator, it asks the OS to create a “pseudoterminal pair” which is a pair of two files

terminal emulator <-> TTY <-> TTY driver <-> TTY <-> program
a “TTY” is the program’s side of the pair

programs use it to:

communicate with the terminal emulator by reading/writing bytes
configure the TTY driver (more on the next page!)

Run tty fo see the current TTY!
the TTY driver is why Ctrl+C does the same thing relatively consistently

program: you press Ctrl+C, I send a signal!
well, unless the program tells me it wants the raw bytes!
some things the TTY driver is in charge of

(you might think “these are unrelated” and you’d be right)

storing the terminal window’s size
sending a SIGHUP signal when you close your terminal
a basic mode for entering text called “canonical mode”
pausing the output and confusing you when you press Ctrl+S
tracking which process is in the “foreground” and sending what you type there

September 8, 2025 at 3:06 PM

Julia Evans

@b0rk.jvns.ca

I've been using White Squirrel for fulfillment for years for wizardzines.com and they're the best.

White Squirrel 📦 @whitesquirrel.com · Sep 3

Due to popular demand, we are setting up a heavily discounted fulfillment service for artists outside the US that are scrambling after the recent tariff / customs policy put in place for shipments to the USA.

September 3, 2025 at 4:34 PM

Julia Evans

@b0rk.jvns.ca

when you learned Git for the first time, what resources did you use? Did you like them? Mostly looking for answers from folks who learned Git in the last 5 years or so.

Looking for resources to potentially add to the Git website

September 3, 2025 at 11:48 AM

Julia Evans

@b0rk.jvns.ca

terminal colours

wizardzines.com/comics/colou...

(from "The Secret Rules of the Terminal", out now!)

$your terminal emulator has 16 configurable colours normal bright black 0 0 red 1 1 green 2 2 yellow 3 3 blue 4 4 purple 5 5 cyan 6 6 white 7 7 these are called “ANSI colours” you can configure them in your terminal emulator’s settings OR run a script that prints escape codes to magically set up your colours https://wzrd.page/scripts (my favourite way!) programs can use ANSI colours by printing an escape code echo -e "\033[34m blue text" 3 means “normal fg colour” 4 means “blue” the default ANSI colours often have bad contrast ls --color often displays directories in ANSI “blue” which can look like this: [bar of illegibly dark text against a dark background, which says “can you read this?”] ANSI “yellow” on white also often has bad contrast “minimum contrast” Picking ANSI colours which always have good contrast is impossible. the only real solution is to use a terminal emulator which has a “minimum contrast” feature (like iTerm or kitty) which will fix contrast issues usually if a program is writing to a pipe, it’ll disable colours $ grep blah file.txt | less grep, represented by a box with a smiley face: better turn off colours so that I don’t accidentally show someone `^[[34ntext here]$

September 2, 2025 at 3:04 PM

Julia Evans

@b0rk.jvns.ca

job control

wizardzines.com/comics/job-c...

(from The Secret Rules of the Terminal, which is out now!)

your shell lets you run many programs (“jobs”) in the same terminal tab

programs can either be:

foreground
background
stopped (which is more like “paused”)

& runs a program in the background

for example I like to convert 100 files in parallel like this:

for i in `seq 1 100`
do
convert $i.png $i.jpg &
done

jobs lists backgrounded & stopped jobs

$ jobs
[1] Running python blah.py &
[2] Stopped vim

use the numbers to bring them to the foreground or background (like fg %2), kill them (kill %2), or disown them
when you close a terminal tab all jobs are killed with a SIGHUP signal

you can stop this with disown or by starting the program with nohup: disown %1 (job number goes here) nohup my_program &
a trick to kill programs if Ctrl+C doesn’t work

press Ctrl+Z to stop the program
run kill %1 to kill it (or kill -9 %1 if you’re feeling extra murderous)

a little flowchart

Three boxes, labelled “running in foreground”, “stopped”, and “running in background”

Ctrl+Z goes from “running in foreground” to “stopped” fg goes from “stopped” to “running in foreground” fg goes from “running in background” to “running in foreground” bg goes from “stopped” to “running in background”

August 26, 2025 at 3:19 PM

Reposted by Julia Evans

Julia Evans

@b0rk.jvns.ca

I'm doing a side project where I'm working on improving a couple of git's man pages and could really use a few test readers. if you're interested, sign up here!

I'd especially love test readers who use git on the command line regularly but are not 100% comfortable with it
forms.gle/gFVUgj79ifHe...

August 20, 2025 at 1:45 PM

Julia Evans

@b0rk.jvns.ca

I'm doing a side project where I'm working on improving a couple of git's man pages and could really use a few test readers. if you're interested, sign up here!

I'd especially love test readers who use git on the command line regularly but are not 100% comfortable with it
forms.gle/gFVUgj79ifHe...

August 20, 2025 at 1:45 PM

Julia Evans

@b0rk.jvns.ca

editing text in a REPL

wizardzines.com/comics/editi...

(from "The Secret Rules of the Terminal", which is out now! wizardzines.com/zines/terminal)

editing text in a REPL doesn’t always work

little stick figure, horrified: when I press my ARROW KEYS it just prints out [[D??? what?
this is because every program has fo implement text editing itself

terminal program author, represented by a nonplussed looking stick figure with medium length straight hair, thinking: but I just want arrow keys to work?? shouldn’t that be automatic?

unix, represented by a box with a smiley face: NOPE you gotta do it
you do gef a few things automatically

backspace (occasionally backspace won’t work and you have to use Ctrl+H instead)
Ctrl+W (delete word)
Ctrl+U (delete line)

(see page 25 for what “automatically” means)
REPLs mostly have the same keyboard shortcuts

there’s a very popular library called “readline”, and everyone either uses it or imitates how it works

for example Ctrl+A (“go to beginning of line”) comes from readline
rlwrap adds readline keyboard shortcuts

for example on my machine the dash shell doesn’t use readline but you can make it better by running:

rlwrap dash
built in programs on Mac don’t use readline

(for example sq1ite3)

this is probably because readline is GPL licensed

They use libedit which is worse. I like to install a sqlite version with readline support and use that instead.

August 19, 2025 at 3:07 PM

Julia Evans

@b0rk.jvns.ca

how your terminal handles mouse clicks

wizardzines.com/comics/the-m...

(from "The Secret Rules of the Terminal", which is out now! wizardzines.com/zines/terminal)

when you click in the terminal, it can either be handled by

your terminal emulator
(represented by a box with a winky cursor face and little arms and legs)
(good if you want to copy text)

or

the program
(represented by a box with a smiley face)
(lots of programs have mouse support!)
programs can tell the terminal emulator to let them handle the mouse

program: if there’s a mouse click, send me escape codes to tell me where it was!

terminal emulator: okay! I’ll disable all my usual mouse functions like “selecting text”!

this is called “mouse reporting”
some programs that have mouse support

tmux: resize a pane! right-click for a menu!
htop: click to sort columns!
micro: text editor with good mouse support
vim: click on the tab bar!
and lots more! (lazygit, mc, zellij, btop…)

how to force the terminal emulator to handle the mouse:

unhappy stick figure with short curly hair, thinking: ugh no I don’t want to focus that pane, I want to COPY SOME TEXT!!!

could be something else too, it depends on your terminal emulator

the scroll wheel

In some programs (like less) the scroll wheel does the same thing as pressing up/down arrow keys really fast

terminal emulator: UP UP UP UP UP UP UP UP UP UP UP UP

in other programs (like lazygit) it uses “mouse reporting” to report where your mouse was when you scrolled
other mouse features your terminal emulator might have

Shift+click (or something) to open a link in a browser
Alt+c1ick (or maybe Option) to move the cursor when editing a command in your shell

August 12, 2025 at 3:05 PM

Julia Evans

@b0rk.jvns.ca

just learned that CSS (as of "Baseline 2023") now supports nesting: caniuse.com/css-nesting

I never managed to start using SCSS so I'm excited to be able to write things like this without a preprocessor:

.cal-link {
right: -18px;
@media (max-width: 800px) {
right: 0;
}
}

August 8, 2025 at 1:27 PM

Reposted by Julia Evans

Christopher Yudichak

@theoddlinguist.bsky.social

I received my physical copy of "The Secret Rules of the Terminal" by @b0rk.jvns.ca yesterday.

I've got—I'm pretty sure—the full set of zines on my shelf. They're probably the reference material I grab most often. Great information well described in a convenient format.

“The Secret Rules of the Terminal” by Julia Evans. The cover depicts three people doing magic in a stone building with arches. They each have accessories featuring imagery of keyboard keys, terminal prompt characters, and a palette of colors.

August 5, 2025 at 5:28 PM

Reposted by Julia Evans

Fatih Altinok

@fatih.6nok.org

Just bought (and read) this zine by @b0rk.jvns.ca and loved it!

It’s bite sized but packs a punch, gives a very good mental model, explains some gotchas and most importantly encourages curiosity.

wizardzines.com/zines/git/

How Git Works

wizardzines.com

August 5, 2025 at 2:26 PM

Julia Evans

@b0rk.jvns.ca

just noticed Bite Size Command Line came out 7 years ago, I still sometimes forget the syntax for lsof and have to look it up at wizardzines.com/comics/lsof/ :)

wizardzines.com/zines/bite-s...

August 5, 2025 at 3:26 PM

Julia Evans

@b0rk.jvns.ca

all of the preorders of "The Secret Rules of the Terminal" have shipped! we promised they'd ship in August and I'm pleased that we managed to get them all shipped before August even arrived

(please send us an email if you run into any problems)

wizardzines.com/zines/termin...

The Secret Rules of the Terminal

wizardzines.com

July 28, 2025 at 7:51 PM

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