jj: hello world

03 Dec, 2025 • 802 words • 4 min • updated 26 Mar, 2026

I am reasonably confident to end up (fully) adopting jj in 2026. Baby steps though.

Can I attempt to start to use jj to manage this blog?

First, the usual:

shell

brew install jj

Second, a basic config file. git requires one too:

     ~/.config/jj/config.toml
     toml 
   
[user]
name = "Thiago Perrotta"
email = "{redacted}"

[ui]
default-command = "log"

So far so good.

Third, initialize a jj repo alongside (“co-located”) the existing git repo of this blog:

     shell
     
   
% jj git init --colocate
Done importing changes from the underlying Git repo.
ignoring git submodule at "vendor/ai.robots.txt"
Setting the revset alias `trunk()` to `master@origin`
Hint: The following remote bookmarks aren't associated with the existing local bookmarks:
  master@origin
Hint: Run the following command to keep local bookmarks updated on future pulls:
  jj bookmark track master@origin
Initialized repo in "."
Hint: Running `git clean -xdf` will remove `.jj/`!

I am fine with the second hint, even though I don’t fully comprehend it:

shell

% jj bookmark track master@origin

I got this advice¹:

For jj in a blog repo (especially with colocated Git):

Use small, focused commits — jj makes this easy; amend frequently with jj amend instead of stashing

Leverage jj log — understand your repo state before operations

Work on branches — jj new -b feature-name for feature work, keeps main clean

Keep commits working — jj can track your working changes automatically

Use jj sync — pulls and pushes in one command with Git

OK.

I know jj does not have the concept of a staging area, thus there’s no jj add. I double-checked:

     shell
     
   
% jj add
error: unrecognized subcommand 'add'

Then what should I do…commit?!

shell

% jj commit

Opens $EDITOR:

add hello world

JJ: Change ID: vvvzruls
JJ: This commit contains the following changes:
JJ:     A content/posts/2025-12-03-jj-hello-world.md
JJ:
JJ: Lines starting with "JJ:" (like this one) will be removed.

Follow-up:

     shell
     
   
% jj commit
Working copy  (@) now at: loyssymn 4ba8427d (empty) (no description set)
Parent commit (@-)      : vvvzruls d6c2ee34 add hello world

Fancy! Now what? I learned that whenever I am lost, jj is your friend. jj (or jj log) is akin to git status and/or git log.

     shell
     
   
% jj
@  loyssymn {redacted email} 2025-12-03 04:00:08 9df24e6a
│  (no description set)
○  vvvzruls {redacted email} 2025-12-03 03:59:00 git_head() d6c2ee34
│  add hello world
│ ○  oqwvuopo {redacted email} 2025-12-03 03:36:43 likes 907c5e72
├─╯  git-freeze
◆  oqwnlpuv {redacted email} 2025-12-02 23:12:39 master a9efb058
│  bytebytego: Product Array Without Current Element
~

There’s also:

     shell
     
   
% jj status
Working copy changes:
M content/posts/2025-12-03-jj-hello-world.md
Working copy  (@) : loyssymn 54ba540b (no description set)
Parent commit (@-): vvvzruls d6c2ee34 add hello world

Whilst I keep adding text to this file…

     shell
     
   
% git st
## HEAD (no branch)
 M content/posts/2025-12-03-jj-hello-world.md

Oh, look! Our friend is still around.

     shell
     
   
% jj amend
error: unrecognized subcommand 'amend'

For more information, try '--help'.
Hint: You probably want `jj squash`. You can configure `aliases.amend = ["squash"]` if you want `jj amend` to work.

Really? Oh.

     shell
     
   
thiago@thiagoperrotta-MacBook-Pro ~blog (git)-[jj/keep/d6c2ee34fe38ec5a63644114c4c3b13bb09401f1]
% jj squash
Working copy  (@) now at: kpumvxpm e60fb5b5 (empty) (no description set)
Parent commit (@-)      : vvvzruls bba2f04e add hello world

Weird:

thiago@thiagoperrotta-MacBook-Pro ~blog (git)-[jj/keep/bba2f04ecd437d8d27e4c8103cb61fc936cd0d89]
% jj
@  kpumvxpm {redacted email} 2025-12-03 04:03:57 41b2cf2f
│  (no description set)
○  vvvzruls {redacted email} 2025-12-03 04:03:21 git_head() bba2f04e
│  add hello world
│ ○  oqwvuopo {redacted email} 2025-12-03 03:36:43 likes 907c5e72
├─╯  git-freeze
◆  oqwnlpuv {redacted email} 2025-12-02 23:12:39 master a9efb058
│  bytebytego: Product Array Without Current Elemen
~
thiago@thiagoperrotta-MacBook-Pro ~blog (git)-[jj/keep/bba2f04ecd437d8d27e4c8103cb61fc936cd0d89]
% jj status
Working copy changes:
M content/posts/2025-12-03-jj-hello-world.md
Working copy  (@) : kpumvxpm 41b2cf2f (no description set)
Parent commit (@-): vvvzruls bba2f04e add hello world
thiago@thiagoperrotta-MacBook-Pro ~blog (git)-[jj/keep/bba2f04ecd437d8d27e4c8103cb61fc936cd0d89]
% git status
## HEAD (no branch)
 M content/posts/2025-12-03-jj-hello-world.md

I thought amend (or squash) would be akin to git commit --amend, but apparently not? I see two nodes.

Remember the advice from a while ago?

     shell
     
   
% jj sync
error: unrecognized subcommand 'sync'

Lame.

Time for jj help -k tutorial (linked to from jj --help).

At this point I just want to end the post. I’ll try jj git push. If I am cut-off, it means it has worked. And we’ll continue this in 2026.

     shell
     
   
% jj git push
Warning: No bookmarks found in the default push revset: remote_bookmarks(remote=origin)..@
Nothing changed.

Errr.

     shell
     
% jj checkout master
error: unrecognized subcommand 'checkout'

Usage: jj [OPTIONS] <COMMAND>

For more information, try '--help'.

     shell
     
   
% jj describe -m "new just: jj hello world"
Working copy  (@) now at: kpumvxpm 516b5d69 new just: jj hello world
Parent commit (@-)      : vvvzruls bba2f04e add hello world

This is the moment of the post when I had to bail out to git.

Somehow two distinct commits were created. :(

Until next time.

From whom? From what? Mystery? I think you know the answer. ↩︎

jj: hello world

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