In Defense of $ and # in the Shell Prompt

Table of Contents

In Defense of the Humble $ and the Fearsome #

(totally subjective opinion, but with love)

This post is not a CTF writeup, nor a 0day exploit, nor anything useful for scoring points on a scoreboard. It’s simply a loving rant about something I see more and more: people removing the $ and # from their prompt.

Yes, those old-school symbols that indicate:

• $ → normal user
• # → root (aka: “if you mess up here, you cry”)

And I’m here to say:

please, let’s not kill them just yet.

The prompt: that little sign that warns you before you screw up

Call it prompt, path, cursor, “where I type commands”, whatever. That little piece of text before what you type isn’t decoration: it’s critical information.

$ command   # normal user
# command   # root

With a single character you know:

Will what I’m about to do break my user… or break the production server?

No whoami, no id, no looking at anything. You see it at a glance and you’re done.

Why do some hackers skip the $ and #?

Because in the hacking and sysadmin world we’re always trying weird things in the prompt, so it’s no surprise that, for whatever reason, many people ditch the $ and #.

I see a lot of prompts like this:

❯
λ
»

Or super polished zsh/fish themes, with:

• user, host, path
• git branch
• exit code
• the moon phase if you’re not careful

…but no trace of $ or #.

The typical reasons:

• “It looks cleaner / more minimalist”
• “I already distinguish by colors”
• “I know what I’m doing, I don’t need that”

Fair enough. Until you leave your cave.

The day colors can’t save you

The “I use colors” argument breaks down very quickly:

• In Markdown, README, blogs, writeups… The color usually disappears. Example:

  # iptables -F
  

  In your terminal you had it in nuclear red with a radioactive background. In the blog: plain text and a face like “well, this must be safe, right?”.

• In a crappy TTY, a random container or a remote machine without your zsh config, your favorite theme doesn’t exist.

• In a screenshot, in a PDF or on a bad monitor during a talk or conference, colors look iffy, but the # is still understood the same way.

Colors are cool, yes. But they don’t travel well. The character does.

Examples where the # should give you chills

It’s much easier to see the danger like this:

# iptables -F
# userdel -r wrong-user
# mv /etc /etc.bak
# mysql -e 'DROP DATABASE production;'

Than like this:

❯ iptables -F
❯ userdel -r wrong-user
❯ mv /etc /etc.bak
❯ mysql -e 'DROP DATABASE production;'

In the second case, if you don’t have context, it looks like any old script. In the first one, the # is already yelling at you:

Hey, this isn’t a toy, are you sure you want to hit Enter?

It won’t always save you, but it’s a free mental brake.

Documentation, writeups and CTFs

In CTFs and writeups, $ and # are pure gold:

• $ → you can copy this as a normal user
• # → this is root / sudo stuff

Typical example in a writeup:

$ sudo -l
# cat /root/root.txt

Even if you’re reading quickly, your brain understands: “ah, okay, here I’m already root”. No colors, no plugins, nothing. In a PDF, in a blog, wherever.

If you remove those symbols, you force the reader to guess the context. And we already have enough to deal with—fighting filters, WAFs, triple URL-encoded payloads, race conditions and logs full of 500 errors—without also fighting the prompt.

The aesthetics argument

Yes, I know: a prompt like:

┌─[ctfer@kali]─[~/ctf/machine]
└──╼ $

looks more “pro” than a sad:

$

And there’s nothing wrong with setting up a nice prompt. But it costs nothing to end it with:

• $ if you’re a user
• # if you’re root

You can have:

• colors
• git
• time
• exit code
• environment (prod/stage/dev)

…and still let one character at the end summarize your privileges.

This is not a standard, it’s a rant

All of this is simply my grumpy shell user opinion:

• Want a prompt with emojis and no $ or #? Go ahead.
• Want a single ❯ symbol for everything? Your terminal, your rules.
• Want to live dangerously without knowing when you’re root? That’s on you 😂

I’m just arguing that, in a world of:

• screenshots,
• CTF blogs,
• colorless markdown,
• random SSH sessions,

the old $ and the old # are still the cheapest and most effective way to see privileges at a glance.

It’s not nostalgia. It’s pure convenience.

TL;DR

• $ → normal user
• # → root
• They’re ugly, but extremely useful.
• Cool colors and themes are fine, but they don’t replace the symbol.
• In writeups, documentation and CTFs they help a lot to understand the context.

And in the end, as always in this world:

Hack however you want, configure your shell however you want… but if you keep the $ and #, you’re certainly not hurting yourself.

Thanks for reading this far. I hope I’ve convinced you a little, and if not, that’s fine too: in the end, what matters is that everyone is happy with their prompt. 😊