Merge pull request #47 from rmoff/stringnotinpwd

Quick post about funny zsh behaviour

content/post/stringnotinpwd.md

@@ -0,0 +1,118 @@
+---
+draft: false
+title: 'cd: string not in pwd'
+date: "2023-10-04T15:36:35Z"
+image: "/images/2023/10/h_DSCF7802.webp"
+thumbnail: "/images/2023/10/t_IMG_8657.webp"
+credit: "https://twitter.com/rmoff/"
+categories:
+- zsh
+---
+
+A brief diversion from my [journey learning Apache Flink](/categories/laf/) to document an interesting `zsh` oddity that briefly tripped me up: 
+
+```shell
+cd: string not in pwd: flink-1.17.1
+```
+
+<!--more-->
+
+This was on the third step of [Flink First Steps](https://nightlies.apache.org/flink/flink-docs-release-1.17/docs/try-flink/local_installation/#browsing-the-project-directory), in which you're instructed to browse the project directory after having downloaded and unarchived the tar. 
+
+```shell
+$ pwd
+/Users/rmoff/flink
+
+$ ls -l
+total 917512
+drwxr-xr-x@ 13 rmoff  staff        416 19 May 12:14 flink-1.17.1
+-rw-r--r--@  1 rmoff  staff  469413690  4 Oct 15:52 flink-1.17.1-bin-scala_2.12.tgz
+```
+
+```shell
+$ cd flink-*
+cd: string not in pwd: flink-1.17.1
+```
+
+Looking at the directory listing, or simply hammering the tab key to auto-complete, most of us wouldn't bother this much more than just entering the full directory name instead: 
+
+```shell
+$ cd flink-1.17.1
+$ ls -l
+total 320
+-rw-r--r--@  1 rmoff  staff   11357 19 May 09:43 LICENSE
+-rw-r--r--@  1 rmoff  staff  145829 19 May 12:14 NOTICE
+-rw-r--r--@  1 rmoff  staff    1309 19 May 09:43 README.txt
+drwxr-xr-x@ 24 rmoff  staff     768 19 May 12:14 bin
+drwxr-xr-x@ 13 rmoff  staff     416 19 May 12:14 conf
+[…]
+```
+
+But the fix isn't half as interesting as the reason :) 
+
+## What's old is new?
+
+Turns out zsh has more than one form of the `cd` command. By using a wildcard the tutorial's instructions avoid having to hard code the version. However, as a result the second type of invocation of zsh's `cd` command is triggered. 
+
+Remember that the directory we're currently in has the archive that we've downloaded and expanded. 
+
+```shell
+$ ls -l
+total 917512
+drwxr-xr-x@ 13 rmoff  staff        416 19 May 12:14 flink-1.17.1
+-rw-r--r--@  1 rmoff  staff  469413690  4 Oct 15:52 flink-1.17.1-bin-scala_2.12.tgz
+```
+
+This means that the wildcard matches not just the unpacked directory, but the archive too. 
+
+```shell
+$ print flink-*
+flink-1.17.1 flink-1.17.1-bin-scala_2.12.tgz
+```
+The important point here is that there is **more than one match to the glob**.
+
+If there is more than one argument passed then the [second form of zsh's `cd`](https://zsh.sourceforge.io/Doc/Release/Shell-Builtin-Commands.html#index-cd) is used: _`cd old new`_. Here, the second argument is substituted for the first, which means that we're effectively entering (if you expand the wildcard):
+
+```bash
+cd flink-1.17.1 flink-1.17.1-bin-scala_2.12.tgz
+```
+
+Which per the syntax will try to replace the value for the "old" parameter (`flink-1.17.1`) in `pwd` (the working directory) with the value for the "new" parameter (`flink-1.17.1-bin-scala_2.12.tgz`)—but the working directory is `/Users/rmoff/flink` and thus the error `string not in pwd: flink-1.17.1`. 
+
+## How is `cd old new` useful? 
+
+Imagine you've got this directory structure: 
+
+```shell
+foo
+├── v1
+│   └── bar
+│       └── wibble
+│           └── bork
+│               └── bork
+│                   └── bork
+└── v2
+    └── bar
+        └── wibble
+            └── bork
+                └── bork
+                    └── bork
+```
+
+You're in the `v1` set of the folders, deep in the structure: 
+
+```shell
+$ pwd
+/Users/rmoff/foo/v1/bar/wibble/bork/bork/bork
+```
+
+Now you want to be in same place but `v2`. You could `cd ../../../../..` and lose count. You could start again from the top (`cd ~/foo/v2/` and type out the full path again). You could probably do other shell magic that you can [tell me about on ~~Twitter~~X](https://twitter.com/rmoff/). Or you could do this: 
+
+```shell
+$ cd v1 v2
+~/foo/v2/bar/wibble/bork/bork/bork
+```
+
+So—possibly useful, but definitely derailing bash `cd` glob assumptions for plenty of folk ;)
+
+([h/t](https://github.com/ohmyzsh/ohmyzsh/issues/10092#issuecomment-894804081))

themes/story/archetypes/default.md

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+draft: false
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