# mkcd: The missing shell shortcut

It seems like you often `cd` to a new directory.
How often?

I have analyzed my [fish shell](https://fishshell.com) history on a Linux machine where it spans from 2019 to 2025 and has just over 100K entries.
If you have seen a fish history file, it looks like a subset of YAML:

```plaintext
- cmd: add-apt-repository ppa:zfs-native/stable
  when: 1342217584
- cmd: nvim dir.sha256
  when: 1614189938
  paths:
    - dir.sha256
```

However, it is [not valid YAML](https://github.com/fish-shell/fish-shell/issues/4675#issuecomment-359205359).
With this in mind, I wrote a script to analyze history line-by-line using Python's helpful [`fileinput`](https://docs.python.org/3/library/fileinput.html) module.

[Download](mkcd/analyze.py).

```python
#! /usr/bin/env python3

import fileinput

mkdir = 0
cd_after_mkdir = 0
after_mkdir = None

for line in fileinput.input(errors="surrogateescape"):
    args = line.split()  # Ignore quoting.

    if args[:2] != ["-", "cmd:"]:
        continue

    match args[2:]:
        case ["mkdir", path, *_] | ["sudo", "mkdir", path, *_]:
            path = path.rstrip("/")

            mkdir += 1
            after_mkdir = path
            continue

        case ["cd", path, *_]:
            path = path.rstrip("/")

            if path == after_mkdir:
                cd_after_mkdir += 1

        case _:
            pass

    after_mkdir = None

print(f"{mkdir = }\n{cd_after_mkdir = }")
```

You can try this script on your history.
Here is what I get on my machine:

```plaintext
> ./analyze.py ~/.local/share/fish/fish_history
mkdir = 1244
cd_after_mkdir = 213
```

213 ÷ 1244 × 100% ≈ 17% of `mkdir` commands are immediately followed by changing to the new directory.
This is for my user account; for root, I have `mkdir = 30` and `cd_after_mkdir = 3`, respectively.
The numbers are approximate.
The script ignores argument quoting, and my shell history covers time after I replaced `mkdir` followed by `cd`.
Still, this seems like a lot.
Why is there no standard shortcut to perform `mkdir` followed by `cd`?
It doesn't seem any prominent shell includes one.
By contrast, `ll` for `ls -l` and `la` for `ls -la` are standard in fish.

I know I didn't invent `mkcd` and only adopted it years after reading the first Internet comment that described it.
This leads me to suspect the friction isn't obvious.
You realize the standard workflow is tiresome _after_ you start using `mkcd`.
(This means you adopt `mkcd` at your peril.)

Where does `mkcd` come from?
[Multiple discovery](!W) is likely because the core idea is so simple.
I have [searched Hacker News](https://hn.algolia.com/?dateEnd=1752323076&dateRange=custom&dateStart=1104537600&page=1&prefix=false&query=mkcd&sort=byDate&type=comment) with the official Algolia search and Reddit and [textfiles.com](https://textfiles.com) using DuckDuckGo and Google.
The earliest instances I found were a [January 2008 comment](https://news.ycombinator.com/item?id=104208) by HN user dreish and an April 2010 post ["mkcd"](https://onethingwell.org/post/561049890/mkcd) by Jack Mottram on the Tumblr blog _One Thing Well_.
The dreish comment uses `mkdir -p`, but Jack Mottram only replaced `mkdir` with `mkdir -p` in May 2010 follow-up ["mkcd improved"](https://onethingwell.org/post/586977440/mkcd-improved) after a message from a reader, suggesting he didn't borrow from the HN comment.
[Searching Usenet Archives](https://www.usenetarchives.com/index.php?s=mkcd&t=0&p=1) finds a [linux.debian.user.german post from 2003](https://www.usenetarchives.com/view.php?id=linux.debian.user.german&mid=PEdWVVkuMTdDLjIxQGdhdGVkLWF0LmJvZmguaXQ%2B) by Robert Michel asking how to implement `mkcd` as a Bash alias.
Other discussions that match "mkcd" on Usenet Archives are about burning optical media.

After seeing the recommendation for `mkcd` enough times, in 2024 I decided to try it.
I implemented it for fish and quickly became a fan.
Over a year later, I can definitely recommend it.
To try it yourself, you can install `mkcd.fish` to your fish functions directory (likely `~/.config/fish/functions/`).

[Download](mkcd/mkcd.fish).

```fish
# From https://dbohdan.com/mkcd
# License: MIT
# https://dbohdan.com/mit-license/2025

function mkcd --argument name --description "Create a directory and 'cd' to it"
    if test (count $argv) -ne 1
        printf 'usage: mkcd name\n' >&2
        return 2
    end

    mkdir -p $name
    cd $name
end
```

## See also

- [My setup](/setup)
- [Small utilities](/small-utils)

## Page metadata

URL: <https://dbohdan.com/mkcd.md>

Published 2025-07-13, updated 2025-07-18.

Tags:

- command line
- fish shell
- personal computing
- shell
- tools