um cli docs

README.md

@@ -12,17 +12,24 @@ It consists of two parts:
 
 Conceptually, `um` is somewhat like org-roam, except without any database dependency. (And it assumes Markdown rather than org, which I don't care for.)
 
-The "database" depends on a few simple ideas:
+This "database" depends on a few simple ideas:
 
-1. A numbered filename specification which serves as unique id. The files are their own representation.
+1. A sequentially numbered filename specification which serves as unique id, like this: `001.foo.md`.  The filesystem is the database. Note that the string descriptor is optional.
 
-2. Placing that same id into the file header, so that concatenated files have reference back to their source. See the `um cat` command.
+2. Placing that same id into the file header, so that concatenated files have reference back to their source - like this:
 
-3. Using a source "journal/" directory, where source files should first be composed and where we can assume a file exists if not elsewhere.
+    ```markdown
+    # 001.foo.md
+    : 2024.01.14
+    ```
+
+    See the `um cat` command for why this matters.
+
+3. Using a source "journal/" directory, where source files should first be composed and where we can assume a file exists if not elsewhere. This matters when trying to navigate back to a source file.
 
 4. Using the built-in emacs `project` package to organize compositions built from these source files.
 
-## installation
+# installation
 
 Clone it:
 
@@ -33,7 +40,6 @@ git clone https://git.bth.moi/bth/um.git ~/um
 Symlink the `um` CLI somewhere in your `PATH`:
 
 ```
-cd ~/um
 ln -s ~/um/shell/um /usr/local/bin/um
 ```
 
@@ -53,3 +59,93 @@ My config looks like this:
   :load-path "~/um/elisp"
 )
 ```
+
+Note the optional setup of `embark`, which allows us to visit files just by invoking `emark-dwim` on a file header. This will also work with `C-x C-f M-n` out of the box.
+
+# CLI usage
+
+To get started, just create an empty directory to serve as content origin. It doesn't matter where or what it's called, since the shell scripts only assume a sequentially numbered collection of files.
+
+## next
+
+Create a new file - and open it with emacsclient by default:
+
+```
+um next
+```
+
+Create a new file with an optional descriptor:
+
+```
+um next foo
+```
+
+## last
+
+`um last` will print the name of the last numbered file. This can be useful on its own, or like this:
+
+```
+um last | xargs emacs
+```
+
+## cat
+
+One of the advantages of the header specification, is that it allows us to `cat` files together without losing track of their origin. This is probably the most important design decision, since the more complicated option would have been to keep all source files intact, and compose larger projects by reference back to the original file only - like org-roam does. This would, however, introduce considerably more complexity, and it would mean that project files become obscure lists of files, instead of content - which would largely defeat the value of git and plaintext in general.
+
+So rather than overengineer, like most engineers do, I choose to stick with plaintext files everywhere, and let the source file serve as history relative to the larger project. It means that the source of truth for my writing projects travels downstream, which is not ideal but largely fine - since git makes history of everything anyway.
+
+All this stupid little command does, is cat files together while placing a Markdown horizontal rule between them, like this:
+
+```sh
+um cat 01.md 02.md
+
+# 01
+: 2024.01.14
+
+---
+
+# 02
+: 2024.01.14
+```
+
+Which means we can pipe the output wherever we like:
+
+```sh
+um cat 01.md 02.md > /tmp/foo.md
+```
+
+## rename
+
+The `um rename` command makes it easier to add or change the string descriptor:
+
+```sh
+um rename 02.md foo
+```
+
+And we get `02.foo.md`.
+
+## tag
+
+The file header allows for an optional block of tags, marked by a `+` like this:
+
+```markdown
+# 02
+: 2024.01.14
++ foo
++ bar
+```
+
+We can then grep for these tags. This command just makes it easier:
+
+```sh
+um tag foo
+02.md
+```
+
+So we can pipe it:
+
+```sh
+um tag foo | xargs um cat > /tmp/foo.md
+```
+
+And there you have the virtue of the Unix philosophy.