Add Clean Up Memory-Hungry Rails Console Processes as a Rails TIL

Was fetching remote then checking out stale local branch

README.md

@@ -6,11 +6,11 @@ A collection of concise write-ups on small things I learn day to day across a
 variety of languages and technologies. These are things that don't really
 warrant a full blog post. These are things I've picked up by [Learning In
 Public™](https://dev.to/jbranchaud/how-i-built-a-learning-machine-45k9) and
-pairing with smart people at Hashrocket.
+working across different projects via [VisualMode](https://www.visualmode.dev/).
 
 For a steady stream of TILs, [sign up for my newsletter](https://visualmode.kit.com/newsletter).
 
-_1715 TILs and counting..._
+_1730 TILs and counting..._
 
 See some of the other learning resources I work on:
 
@@ -131,6 +131,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Clean Up Your Brew Installations](brew/clean-up-your-brew-installations.md)
 - [Configure Brew Environment Variables](brew/configure-brew-environment-variables.md)
 - [Export List Of Everything Installed By Brew](brew/export-list-of-everything-installed-by-brew.md)
+- [Install From Nonstandard Brewfile](brew/install-from-nonstandard-brewfile.md)
 - [Install Go Packages In Brewfile](brew/install-go-packages-in-brewfile.md)
 - [List All Services Managed By Brew](brew/list-all-services-managed-by-brew.md)
 
@@ -157,8 +158,10 @@ If you've learned something here, support my efforts writing daily TILs by
 
 ### Claude Code
 
+- [Allow Edits From The Start](claude-code/allow-edits-from-the-start.md)
 - [Monitor Usage Limits From CLI](claude-code/monitor-usage-limits-from-cli.md)
 - [Open Current Prompt In Default Editor](claude-code/open-current-prompt-in-default-editor.md)
+- [Resume Specific Session](claude-code/resume-specific-session.md)
 
 ### Clojure
 
@@ -348,6 +351,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Count Number Of Commits On A Branch](git/count-number-of-commits-on-a-branch.md)
 - [Create A New Branch With Git Switch](git/create-a-new-branch-with-git-switch.md)
 - [Delete All Untracked Files](git/delete-all-untracked-files.md)
+- [Determine Absolute Path Of Top-Level Project Directory](git/determine-absolute-path-of-top-level-project-directory.md)
 - [Determine The Hash Id For A Blob](git/determine-the-hash-id-for-a-blob.md)
 - [Diffing With Patience](git/diffing-with-patience.md)
 - [Dropping Commits With Git Rebase](git/dropping-commits-with-git-rebase.md)
@@ -423,6 +427,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Show What Is In A Stash](git/show-what-is-in-a-stash.md)
 - [Single Key Presses in Interactive Mode](git/single-key-presses-in-interactive-mode.md)
 - [Skip A Bad Commit When Bisecting](git/skip-a-bad-commit-when-bisecting.md)
+- [Skip Git Hooks As Needed](git/skip-git-hooks-as-needed.md)
 - [Skip Pre-Commit Hooks](git/skip-pre-commit-hooks.md)
 - [Staging Changes Within Vim](git/staging-changes-within-vim.md)
 - [Staging Stashes Interactively](git/staging-stashes-interactively.md)
@@ -500,6 +505,7 @@ If you've learned something here, support my efforts writing daily TILs by
 
 ### Heroku
 
+- [Check Ruby Version For Production App](heroku/check-ruby-version-for-production-app.md)
 - [Connect To A Database By Color](heroku/connect-to-a-database-by-color.md)
 - [Deploy A Review App To A Different Stack](heroku/deploy-a-review-app-to-a-different-stack.md)
 - [Diagnose Problems In A Heroku Postgres Database](heroku/diagnose-problems-in-a-heroku-postgres-database.md)
@@ -545,6 +551,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Focus The URL Bar](internet/focus-the-url-bar.md)
 - [Get Random Images From Unsplash](internet/get-random-images-from-unsplash.md)
 - [Grab The RSS Feed For A Substack Blog](internet/grab-the-rss-feed-for-a-substack-blog.md)
+- [Hide Overflowing Text For Google Sheets Column](internet/hide-overflowing-text-for-google-sheets-column.md)
 - [Search Tweets By Author](internet/search-tweets-by-author.md)
 - [Show All Pivotal Stories With Blockers](internet/show-all-pivotal-stories-with-blockers.md)
 - [Verify Site Ownership With DNS Record](internet/verify-site-ownership-with-dns-record.md)
@@ -746,6 +753,7 @@ If you've learned something here, support my efforts writing daily TILs by
 
 - [Create Umbrella Task For All Test Tasks](mise/create-umbrella-task-for-all-test-tasks.md)
 - [List The Files Being Loaded By Mise](mise/list-the-files-being-loaded-by-mise.md)
+- [Look In Ruby Version Dotfile](mise/look-in-ruby-version-dotfile.md)
 - [Preserve Color Output For Task Command](mise/preserve-color-output-for-task-command.md)
 - [Read Existing Dot Env File Into Env Vars](mise/read-existing-dot-env-file-into-env-vars.md)
 - [Run A Command With Specific Tool Version](mise/run-a-command-with-specific-tool-version.md)
@@ -1065,6 +1073,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Check If ActiveRecord Update Fails](rails/check-if-activerecord-update-fails.md)
 - [Check If Any Records Have A Null Value](rails/check-if-any-records-have-a-null-value.md)
 - [Check Specific Attributes On ActiveRecord Array](rails/check-specific-attributes-on-activerecord-array.md)
+- [Clean Up Memory Hungry Rails Console Processes](rails/clean-up-memory-hungry-rails-console-processes.md)
 - [Code Statistics For An Application](rails/code-statistics-for-an-application.md)
 - [Columns With Default Values Are Nil On Create](rails/columns-with-default-values-are-nil-on-create.md)
 - [Comparing DateTimes Down To Second Precision](rails/comparing-datetimes-down-to-second-precision.md)
@@ -1558,6 +1567,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Kill Other Connections To A Session](tmux/kill-other-connections-to-a-session.md)
 - [Kill The Current Session](tmux/kill-the-current-session.md)
 - [List All Key Bindings](tmux/list-all-key-bindings.md)
+- [List Processes Running Across All Session](tmux/list-processes-running-across-all-sessions.md)
 - [List Sessions](tmux/list-sessions.md)
 - [Open New Splits To The Current Directory](tmux/open-new-splits-to-the-current-directory.md)
 - [Open New Window With A Specific Directory](tmux/open-new-window-with-a-specific-directory.md)
@@ -1604,6 +1614,7 @@ If you've learned something here, support my efforts writing daily TILs by
 ### Unix
 
 - [All The Environment Variables](unix/all-the-environment-variables.md)
+- [Apply Successive Filters To Lines In Less](unix/apply-successive-filters-to-lines-in-less.md)
 - [Authorize A cURL Request](unix/authorize-a-curl-request.md)
 - [Cat A File With Line Numbers](unix/cat-a-file-with-line-numbers.md)
 - [Cat Files With Color Using Bat](unix/cat-files-with-color-using-bat.md)
@@ -1634,9 +1645,11 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Curling For Headers](unix/curling-for-headers.md)
 - [Curling With Basic Auth Credentials](unix/curling-with-basic-auth-credentials.md)
 - [Determine ipv4 And ipv6 Public IP Addresses](unix/determine-ipv4-and-ipv6-public-ip-addresses.md)
+- [Diff Two Files In Unified Format](unix/diff-two-files-in-unified-format.md)
 - [Different Ways To Generate A v4 UUID](unix/different-ways-to-generate-a-v4-uuid.md)
 - [Display All The Terminal Colors](unix/display-all-the-terminal-colors.md)
 - [Display Free Disk Space](unix/display-free-disk-space.md)
+- [Display Line Numbers While Using Less](unix/display-line-numbers-while-using-less.md)
 - [Display The Contents Of A Directory As A Tree](unix/display-the-contents-of-a-directory-as-a-tree.md)
 - [Do A Dry Run Of An rsync](unix/do-a-dry-run-of-an-rsync.md)
 - [Do Not Overwrite Existing Files](unix/do-not-overwrite-existing-files.md)
@@ -1745,6 +1758,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Show A File Preview When Searching With FZF](unix/show-a-file-preview-when-searching-with-fzf.md)
 - [Show Disk Usage For The Current Directory](unix/show-disk-usage-for-the-current-directory.md)
 - [Show The Size Of Everything In A Directory](unix/show-the-size-of-everything-in-a-directory.md)
+- [Show Tree View Of Processes And Subprocesses](unix/show-tree-view-of-processes-and-subprocesses.md)
 - [Skip Paging If Output Fits On Screen With Less](unix/skip-paging-if-output-fits-on-screen-with-less.md)
 - [SSH Escape Sequences](unix/ssh-escape-sequences.md)
 - [SSH With Port Forwarding](unix/ssh-with-port-forwarding.md)
@@ -1760,6 +1774,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Unrestrict Where ripgrep Searches](unix/unrestrict-where-ripgrep-searches.md)
 - [Update Package Versions Known By asdf Plugin](unix/update-package-versions-known-by-asdf-plugin.md)
 - [Use fzf To Change Directories](unix/use-fzf-to-change-directories.md)
+- [Use Negative Lookbehind Matching With ripgrep](unix/use-negative-lookbehind-matching-with-ripgrep.md)
 - [Use Regex Pattern Matching With Grep](unix/use-regex-pattern-matching-with-grep.md)
 - [View A Web Page In The Terminal](unix/view-a-web-page-in-the-terminal.md)
 - [View The Source For A Brew Formula](unix/view-the-source-for-a-brew-formula.md)
@@ -2056,7 +2071,7 @@ I shamelessly stole this idea from
 
 ## License
 
-© 2015-2025 Josh Branchaud
+© 2015-2026 Josh Branchaud
 
 This repository is licensed under the MIT license. See `LICENSE` for
 details.

Taskfile.yml

@@ -32,8 +32,7 @@ tasks:
   notes:sync:
     desc: Sync latest changes from the notes submodule
     cmds:
-      - git submodule update --remote {{.NOTES_DIR}}
-      - cd {{.NOTES_DIR}} && git checkout main
+      - cd {{.NOTES_DIR}} && git checkout main && git pull
     silent: false
 
   notes:open:
@@ -49,6 +48,7 @@ tasks:
     cmds:
       - git add NOTES.md
       - git commit -m "Update notes - $(date '+%Y-%m-%d %H:%M')"
+      - git pull --rebase
       - git push
     status:
       - git diff --exit-code NOTES.md
@@ -60,11 +60,6 @@ tasks:
     cmds:
       - git status
 
-  notes:pull:
-    desc: Pull latest changes (alias for sync)
-    cmds:
-      - task notes:sync
-
   notes:diff:
     desc: Show uncommitted changes in notes
     dir: '{{.NOTES_DIR}}'

brew/install-from-nonstandard-brewfile.md

@@ -0,0 +1,25 @@
+# Install From Nonstandard Brewfile
+
+When you want to install the packages listed in the `Brewfile` for your current
+project (or dotfiles), you can run:
+
+```bash
+$ brew bundle
+```
+
+And `brew` knows to look for and use the `Brewfile` in the current directory.
+
+If, however, you are trying to run `brew bundle` for a `Brewfile` located
+somewhere besides the current directory *OR* you want to target a file with a
+non-standard name (like
+[`Brewfile.personal`](https://github.com/jbranchaud/dotfiles/blob/main/Brewfile.personal)),
+then you can use the `--file` flag.
+
+```bash
+$ brew bundle --file Brewfile.personal
+```
+
+This is what I do [here in my `dotfiles`
+repo](https://github.com/jbranchaud/dotfiles/blob/b053f6251cae7ed52f698fc2a2c40ba82c5881b0/installer/mac-setup.sh#L42-L48).
+
+See `man brew` and find the section on `brew bundle` for more details.

claude-code/allow-edits-from-the-start.md

@@ -0,0 +1,35 @@
+# Allow Edits From The Start
+
+A common pattern for me when using Claude Code is that I start it up in a
+project, I prompt it with a question or feature spec, it either comes up with a
+plan or just starts working, and as soon as it is ready to make its first edits
+to a file, it prompts me something like:
+
+```
+ Do you want to make this edit to Taskfile.yml?
+ ❯ 1. Yes
+   2. Yes, allow all edits during this session (shift+tab)
+   3. Type here to tell Claude what to do differently
+```
+
+That's a nice default so that I don't get surprised by Claude Code editing a
+bunch of files.
+
+However, if I'm in a git-backed project and I'm going into a session intending
+to make edits, then I can skip the formalities. I can tell Claude Code when
+starting up the session that edits are allowed.
+
+```sh
+$ claude --permission-mode acceptEdits
+```
+
+When I do this, I'll see the following indicator below the prompt input field:
+
+```
+  ⏵⏵ accept edits on (shift+tab to cycle)
+```
+
+If I've already started `claude` but I forgot to specify that permission mode, I
+can also toggle right into _accept edits_ by hitting `Shift+Tab`.
+
+[source](https://www.youtube.com/watch?v=_IK18goX4X8)

claude-code/resume-specific-session.md

@@ -0,0 +1,22 @@
+# Resume Specific Session
+
+There are a few different ways to resume a [Claude
+Code](https://code.claude.com/docs/en/overview) session.
+
+First, if I have exited a session for the current project and I want to pick
+back up with that most recent one, then I can use `claude --continue`.
+
+If I have had a few recent sessions for the current project and I want to
+remember what they were and pick up where I left off with one of them, then I
+can use `claude --resume` (with no argument). That will open a picker where I
+can browser through a summary of the recent sessions based on their starting
+prompt. The one I pick is the session that will be resumed.
+
+Finally, if I have grabbed a specific session ID (UUID) during the session from
+the `/status` output, then I can reference that value directly.
+
+```sh
+$ claude --resume 92170532-be31-4a91-b2a9-025b8fa78232
+```
+
+See `claude --help` for more details.

git/determine-absolute-path-of-top-level-project-directory.md

@@ -0,0 +1,39 @@
+# Determine Absolute Path Of Top-Level Project Directory
+
+The `git rev-parse` command is a git plumbing command for parsing different
+kinds of things in git into a canonical form that can be used in a deterministic
+way by scripts. I would typically think of using it to work with branch names,
+tags, and other kinds of refs.
+
+There is a handy, sorta off-label use for it in determining the absolute path of
+the root directory for the current git repository. Use the `--show-toplevel`
+flag with no other arguments.
+
+```bash
+❯ git rev-parse --show-toplevel
+/Users/lastword/dev/jbranchaud/til
+```
+
+Here, I am in the local copy of [my TIL repo](https://github.com/jbranchaud/til). This command gives me the absolute
+path of the top-level directory where that `.git` directory resides.
+
+This is useful for scripts that need to orient themselves to the current
+project's top-level directory regardless of what directory they are being
+executed from. This is useful for things like a git hook script or monorepos
+with scripts located in a specific sub-project directory.
+
+Also worth mentioning is the `--show-superproject-working-tree` flag. In my TIL
+repo, I have a private repository included as a submodule. Within that directory
+`--show-toplevel` will produce the absolute path to the submodule. If I instead
+want the absolute path of the _super project_ (in this case TIL), then I can use
+this other flag.
+
+```bash
+❯ git rev-parse --show-toplevel
+/Users/lastword/dev/jbranchaud/til/notes
+
+❯ git rev-parse --show-superproject-working-tree
+/Users/lastword/dev/jbranchaud/til
+```
+
+See `man git-rev-parse` for more details.

git/skip-git-hooks-as-needed.md

@@ -0,0 +1,33 @@
+# Skip Git Hooks As Needed
+
+Projects have Git hooks configured for all sorts of reasons. Most common are
+`pre-commit` hooks which verify certain aspects of the contents of a commit.
+A `pre-commit` hook could check that the tests all pass, that the changes don't
+include any debugging statements, and so forth. There are all kinds of hooks
+though, like `pre-rebase` and `post-checkout`.
+
+These hooks can sometimes get in the way and we may need to skip or disable them
+on a one-off basis.
+
+Several Git commands offer a `--no-verify` flag which can skip running the hook
+associated with that command.
+
+- `git commit --no-verify` (skips `pre-commit` and `commit-msg` hooks)
+- `git push --no-verify` (skips `pre-push` hook)
+- `git merge --no-verify` (skips `pre-merge-commit` hook)
+- `git am --no-verify` (skips `applypatch-msg` and `pre-applypatch` hooks)
+
+If you look in the `.git/hooks` directory, there are several other hooks not
+covered by the above. So, what if I am doing an action like `git checkout` and I
+want to skip the `post-checkout` hook?
+
+I can override the `hooksPath` config for that one command with the `-c` flag.
+
+```sh
+$ git -c core.hooksPath=/dev/null checkout ...
+```
+
+By setting it to `/dev/null`, it will find *no* hooks available, so none will be
+executed for this command.
+
+See `man git-config` for more details on `core.hooksPath`.

heroku/check-ruby-version-for-production-app.md

@@ -0,0 +1,32 @@
+# Check Ruby Version For Production App
+
+While deploying a fresh Rails app to Heroku recently, I ran into an issue. The
+`it` block argument wasn't working despite being on Ruby 4.0. Or so I thought.
+
+Running the following command reported the Ruby version of that Heroku server
+instance:
+
+```bash
+❯ heroku run -- ruby --version
+Running ruby --version on ⬢ my-app... up, run.3090
+ruby 3.3.9 (2025-07-24 revision f5c772fc7c) [x86_64-linux]
+```
+
+I was on `3.3.9` which must have been the fallback default at the time.
+
+Though I had set the Ruby version in my `.ruby-version` file, I had neglected to
+specify it in the `Gemfile` as well. Once I added it to the `Gemfile` and
+redeployed, my Heroku server instance was running the expected version of Ruby.
+
+```bash
+❯ heroku run -- ruby --version
+Running ruby --version on ⬢ my-app... up, run.5353
+ruby 4.0.0 (2025-12-25 revision 553f1675f3) +PRISM [x86_64-linux]
+```
+
+Note: because [I have set `HEROKU_ORGANIZATION` and
+`HEROKU_APP`](set-default-team-and-app-for-project.md) in my environment
+(`.envrc`) for the local copy of the app, I don't need to specify those when
+running the `heroku run` command above.
+
+See `heroku run --help` for more details.

internet/hide-overflowing-text-for-google-sheets-column.md

@@ -0,0 +1,12 @@
+# Hide Overflowing Text For Google Sheets Column
+
+I imported a big CSV into a new Google Sheets document. This included a
+"Description" column with many of the descriptions varying between 50 and 80
+characters. The bottom line is that the description column was flowing over the
+top of the columns next to it. Instead of expanding the width of that column as
+far as the largest description, I wanted to hide the _overflow_.
+
+The way to do this in Google Sheets is to highlight the entire column by
+clicking on the column grouping. Then under the _Format_ menu item is a
+_Wrapping_ submenu. The _Clip_ option is what I was looking for because it clips
+the text that gets shown at the edge of the column.

mise/look-in-ruby-version-dotfile.md

@@ -0,0 +1,27 @@
+# Look In Ruby Version Dotfile
+
+Newer versions of [`mise`](https://mise.jdx.dev/dev-tools/) specifically only
+look for tool versions in `mise.toml` as well as the asdf `.tool-versions` file.
+A lot of Ruby projects use the `.ruby-version` file to indicate the Ruby version
+of a project. To continue to use the `.ruby-version` file instead of migrating
+to `mise.toml`, you need to tell `mise` that you prefer to use the idiomatic
+version file.
+
+I added the following line to my
+[`~/.config/mise/config.toml`](https://github.com/jbranchaud/dotfiles/commit/8edeb7a9c53500e89e88b4079cbd1859ebebcbda)
+file:
+
+```toml
+idiomatic_version_file_enable_tools = ["ruby"]
+```
+
+Now, whenever `mise` is looking for the specified Ruby version of a project, it
+will also look for `.ruby-version`.
+
+Here is a [full list of idomatic version files supported by
+`mise`](https://mise.jdx.dev/configuration.html#idiomatic-version-files).
+
+See
+[`idiomatic_version_file_enable_tools`](https://mise.jdx.dev/configuration/settings.html#idiomatic_version_file_enable_tools)
+as well as the [Ruby-specific documentation](https://mise.jdx.dev/lang/ruby.html#ruby-version-and-gemfile-support)
+for more details.

rails/clean-up-memory-hungry-rails-console-processes.md

@@ -0,0 +1,43 @@
+# Clean Up Memory Hungry Rails Console Processes
+
+I noticed (using `htop`) that a remote server hosting a Rails app had most of
+its RAM being actively consumed. This was hindering my ability to run a fresh
+deploy because the deploy processes had to do a ton of memory swapping which
+drastically slowed the whole thing down.
+
+With some investigation, I discovered that most of the memory was being consumed
+by a handful of `rails console` processes. I didn't have any known active `rails console` processes that I was using. That combined with the dates of these
+processes starting way in the past suggested to me that these were abandoned
+processes that hadn't been properly cleaned up.
+
+```bash
+server:~# ps aux | grep rails
+32767     878915  0.0  0.0 1227160  936 pts/0    Ssl+  2025   0:03 /exec rails console
+32767     878942  0.9  6.5 830996 261748 pts/0   Rl+   2025 249:51 ruby /app/bin/rails console
+32767    3004097  0.0  0.0 1227160  692 pts/0    Ssl+  2025   0:04 /exec rails console
+32767    3004129  0.9  6.4 834672 257228 pts/0   Dl+   2025 406:31 ruby /app/bin/rails console
+32767    3048582  0.0  0.0 1227160  940 pts/0    Ssl+ Jan09   0:00 /exec rails console
+32767    3048611  1.1  6.3 829936 253484 pts/0   Dl+  Jan09  60:50 ruby /app/bin/rails console
+32767    3060033  0.0  0.0 1227160  944 pts/0    Ssl+  2025   0:04 /exec rails console
+32767    3060063  0.9  6.5 838084 260812 pts/0   Rl+   2025 405:37 ruby /app/bin/rails console
+root     3699372  0.0  0.0   7008  1300 pts/0    S+   15:51   0:00 grep --color=auto rails
+server:~# ps aux | grep 'rails console' | awk '{sum+=$6} END {print sum/1024 " MB"}'
+1014.64 MB
+```
+
+As we can see by tacking on this `awk` command, these processes are consuming
+1GB of memory.
+
+Each of these is a pair of processes. A parent process (`/exec rails console`)
+that kicks off and supervises the memory-hungry child process (`ruby /app/bin/rails console`).
+
+To free up this memory, I targeted each of the parent processes with a `kill`
+command one by one. For example:
+
+```bash
+server:~# kill 878915
+```
+
+I suspect that I may have left the occasional terminal tab open with one of
+these `rails console` processes running and the SSH connection was getting
+killed without the `rails console` getting killed with it.

tmux/list-processes-running-across-all-sessions.md

@@ -0,0 +1,46 @@
+# List Processes Running Across All Session
+
+I wanted an overview of all the processes running across all the tmux sessions
+that I have running on my machine right now. The `list-panes` command (with the
+`-a` flag) gives me a listing of all the panes across all session of the current
+tmux server.
+
+That output on its own isn't giving me quite the info I'm looking for though.
+With the `-f` (_format_) flag, I can use variables available in that context
+like `session_name`, `pane_pid`, and `pane_current_command`.
+
+I can assemble the details I want into a command like this:
+
+```bash
+❯ tmux list-panes -a -F "#{session_name}:#{window_index}.#{pane_index} #{pane_pid} #{pane_current_command}"
+PLP:1.1 62364 zsh
+TIL:1.1 62345 nvim
+TIL:1.2 65838 task
+TIL:2.1 11428 tmux
+client-app:1.1 62373 ssh
+client-app:1.2 10796 zsh
+client-app:1.3 63081 zsh
+client-app:2.1 61115 overmind
+client-app:3.1 82608 zsh
+visualmode-dev:1.1 52237 zsh
+```
+
+This gives me the details I want, but I can take it a step further by piping it
+to the `column` command to improve the formatting a little:
+
+```bash
+❯ tmux list-panes -a -F "#{session_name}:#{window_index}.#{pane_index} #{pane_pid} #{pane_current_command}" \
+  | column -t
+PLP:1.1             62364  zsh
+TIL:1.1             62345  nvim
+TIL:1.2             65838  task
+TIL:2.1             11428  tmux
+client-app:1.1      62373  ssh
+client-app:1.2      10796  zsh
+client-app:1.3      63081  zsh
+client-app:2.1      61115  overmind
+client-app:3.1      82608  zsh
+visualmode-dev:1.1  52237  zsh
+```
+
+See `man tmux` and, in particular, the `FORMATS` section for more details.

unix/apply-successive-filters-to-lines-in-less.md

@@ -0,0 +1,33 @@
+# Apply Successive Filters To Lines In Less
+
+Let's say I've opened a large Rails log file with `less`:
+
+```bash
+$ less logs/development.log
+```
+
+I have an idea of what I'm looking for, but there is way more noise than signal.
+I can start to filter out some of the noise. The `&` command starts a filter
+prompt. If I start to filter by something like `INSERT INTO`, then a ton of
+lines disappear leaving just those matching that pattern.
+
+Scrolling through the current set of lines, I start to have a better idea of
+what I'm looking for, but there is still too much noise. I can apply an
+additional successive filter on the remaining lines by hitting `&` again and
+entering in another pattern -- e.g. `GoodJob`.
+
+Now I only see lines that contain both `INSERT INTO` and `GoodJob` somewhere in
+them.
+
+As `less` puts it:
+
+> Multiple & commands may be entered, in which case only lines which match all
+> of the patterns will be displayed.
+
+If I want to undo all the filtering, I just need to enter an empty `&` filter
+prompt and it will reset things back to displaying all lines.
+
+> If pattern is empty (if you type & immediately followed by ENTER), any
+> filtering is turned off, and all lines are displayed.
+
+See `man less` for more details.

unix/diff-two-files-in-unified-format.md

@@ -0,0 +1,78 @@
+# Diff Two Files In Unified Format
+
+The `diff` command is a standalone utility that can be used to get the
+difference between two files. It is similar to what you might expect when
+running `git diff` which compares two different versions of the same file. The
+`diff` command predates `git` and its unified format is what became the standard
+that `git` uses for its own diff implementation.
+
+Running `diff` with two files as is gives output like the following:
+
+```bash
+❯ diff startup.sh startup2.sh
+10,13c10,14
+< declare -A SESSIONS=(
+<   ["TIL"]="$HOME/dev/jbranchaud/til:setup_til"
+<   ["PLP"]="$HOME/dev/jbranchaud/pool-league-pro:"
+<   ["client-app"]="$HOME/dev/client/client-app:"
+---
+> # Sessions will be created in the order listed here
+> SESSIONS=(
+>   "TIL:$HOME/dev/jbranchaud/til:setup_til"
+>   "PLP:$HOME/dev/jbranchaud/pool-league-pro:"
+>   "client-app:$HOME/dev/client/client-app:"
+73,74c74,75
+<   for session_name in TIL PLP client-app; do
+<     IFS=':' read -r directory setup_function <<<"${SESSIONS[$session_name]}"
+---
+>   for session_config in "${SESSIONS[@]}"; do
+>     IFS=':' read -r session_name directory setup_function <<<"$session_config"
+```
+
+That's readable at a glance, but the unified format (with the `-u` flag) can
+provide more context:
+
+```bash
+❯ diff -u startup.sh startup2.sh
+--- startup.sh  2026-01-10 12:46:52
++++ startup2.sh 2026-01-10 12:48:00
+@@ -7,10 +7,11 @@
+
+ # Session configurations
+ # Format: "session_name:directory:setup_function"
+-declare -A SESSIONS=(
+-  ["TIL"]="$HOME/dev/jbranchaud/til:setup_til"
+-  ["PLP"]="$HOME/dev/jbranchaud/pool-league-pro:"
+-  ["client-app"]="$HOME/dev/client/client-app:"
++# Sessions will be created in the order listed here
++SESSIONS=(
++  "TIL:$HOME/dev/jbranchaud/til:setup_til"
++  "PLP:$HOME/dev/jbranchaud/pool-league-pro:"
++  "client-app:$HOME/dev/client/client-app:"
+ )
+
+ # Setup function for TIL session
+@@ -70,8 +71,8 @@
+   echo ""
+
+   # Create sessions in order
+-  for session_name in TIL PLP client-app; do
+-    IFS=':' read -r directory setup_function <<<"${SESSIONS[$session_name]}"
++  for session_config in "${SESSIONS[@]}"; do
++    IFS=':' read -r session_name directory setup_function <<<"$session_config"
+     create_session "$session_name" "$directory" "$setup_function"
+   done
+```
+
+Here we get additional context like surrounding lines and file name details.
+
+While this is useful on its own, it also has the added benefit of making the
+output compatible with other tools we may already be using. For instance, I'm
+already using [delta](https://github.com/dandavison/delta) as my [git pager](https://github.com/jbranchaud/dotfiles/blob/main/gitconfig#L51) and [git differ](https://github.com/jbranchaud/dotfiles/blob/main/gitconfig#L139).
+
+With the unified format, I can pipe the output directly to `delta` to get a
+better view of the diff that is colorized and includes syntax highlighting.
+
+```bash
+❯ diff -u startup.sh startup2.sh | delta
+```

unix/display-line-numbers-while-using-less.md

@@ -0,0 +1,27 @@
+# Display Line Numbers While Using Less
+
+Including line numbers while viewing files with `less` can provide useful
+context for understanding where you are within the file. This is especially true
+if you've used `&` to filter down to lines that match a pattern.
+
+You can start `less` with line numbers with the `-N` flag (or `--LINE-NUMBERS`
+if you really want to spell it out).
+
+```bash
+$ less -N log/development.log
+```
+
+If you've already started up `less` and wish you had included line numbers,
+there is no reason to restart it with the flag. Instead, toggle the line numbers
+option on within the `less` process. To do this, type `-N`. It will prompt you
+with `Constantly display line numbers (press RETURN)`. Hit enter and line
+numbers will appear to the left of each line in the file.
+
+Similarly, to toggle line numbers back off within `less`, hit `-n` (lower-case
+`n`), accept the prompt, and back off they go.
+
+Both of these (`-N`/`-n`) are options being set (toggled) via the `-` command.
+There are many other options like these that can be configured within a `less`
+session in the same way.
+
+See `man less` and find the `-` command and the available `OPTIONS`.

unix/show-tree-view-of-processes-and-subprocesses.md

@@ -0,0 +1,36 @@
+# Show Tree View Of Processes And Subprocesses
+
+Though you can cobble together a command on a MacOS Unix system to output a
+hierarchical tree view of a parent process and its descendent subprocesses, it
+is easier to [`brew install pstree`](https://github.com/FredHucht/pstree) and
+use that.
+
+Here is what I see when I run it for a _pid_ that corresponds to a `tmux`
+session that I have running locally:
+
+```bash
+❯ pstree 61690
+-+= 61690 lastword tmux new-session -d -s TIL -c /Users/lastword/dev/jbranchaud/til
+ |--= 63081 lastword /bin/zsh
+ |-+= 11428 lastword zsh
+ | \-+= 48511 lastword pstree 61690
+ |   \--- 48512 root ps -axwwo user,pid,ppid,pgid,command
+ |-+= 62345 lastword zsh
+ | \--= 06031 lastword claude
+ |--= 62364 lastword /bin/zsh
+ |-+= 62373 lastword zsh
+ | \--= 64407 lastword ssh my-app-staging
+ |-+= 61115 lastword /bin/zsh
+ | \-+= 61579 lastword overmind start -f Procfile.dev
+ |   \--- 61586 lastword tmux -C -L overmind-my-app-abc123 new -n web -s my-app -P -F %overmind-process #{pane_id} web #{pane_pid} /var/folders/zc/abc123/T/overmin
+ |--= 52237 lastword /bin/zsh
+ |--= 82608 lastword /bin/zsh
+ \--= 10796 lastword /bin/zsh
+```
+
+I was looking for a frozen `claude` process that was part of this session. And I
+found it about halfway down that list -- `06031`. Now I can run `kill` on that
+process as needed.
+
+For some additional context, I initially found the _pid_ for the `tmux` session
+by running `ps aux | grep tmux` and looking through those results.

unix/use-negative-lookbehind-matching-with-ripgrep.md

@@ -0,0 +1,42 @@
+# Use Negative Lookbehind Matching With ripgrep
+
+The most straightforward way to use `ripgrep` is to hand it a pattern. It will
+take that pattern and move forward through each file trying to find matches.
+
+```bash
+$ rg 'TwilioClient\.new'
+```
+
+That will find all occurrences of `TwilioClient.new` in available project files.
+
+What if that pattern is too permissive though? That is going to match on
+occurrences of `TwilioClient.new` as well as things like
+`LoggingTwilioClient.new`. If we want to exclude the latter, there are a few
+ways to do that. One of them being the use of [the _negative lookbehind_ regex
+feature](https://www.pcre.org/current/doc/html/pcre2syntax.html#SEC23) that is
+available with PCRE2 (Perl-Compatible Regular Expressions).
+
+A _negative lookbehind_ is like a standard pattern. We look forward through the
+document for the base pattern (like `TwilioClient\.new`). However, once we find
+that match, we then look back at the previous characters and if they match our
+negative lookbehind pattern, then it is no longer a positive match.
+
+We can use one of the following to forms to achieve this:
+
+```
+  (?<!...)                    )
+  (*nlb:...)                  ) negative lookbehind
+  (*negative_lookbehind:...)  )
+```
+
+For instance, here is what this looks like for our example:
+
+```bash
+$ rg -P '(?<!Logging)TwilioClient\.new'
+```
+
+Note: we have to use the `-P` flag to tell `ripgrep` that we are using PCRE2
+syntax. Otherwise, it assumes a simpler regex syntax that doesn't support
+_negative lookbehind_.
+
+See `man rg` for more details.