add the old snippet md files

old_snippets/shell-for-loops.en.md

@@ -0,0 +1,102 @@
+---
+title: "for loops in bash / zsh shells"
+date: 2020-01-12T11:54:38+01:00
+draft: false
+snippet_types: ["zsh", "built-ins"]
+---
+
+Looping directly in the shell is something I do at lease once a week and it's a great time saver.
+Here I want to run through a concrete example of how to use for loops to mass move and rename files.
+
+During process of getting this snippet section of my site off the ground I realize I had put a bunch
+of markdown files into named directories when I could have just named the files better and done without
+the directories. What I needed to do was **mv** the files out of these dirs and rename them to the
+name of the dir plus add the ".en.md" extension.
+
+Here is the old directory structure:
+
+```shell
+$ tree
+.
+└── snippets
+    ├── _index.en.md
+    ├── aws-cloud-front-inval
+    │   └── index.en.md
+    ├── aws-s3-sync
+    │   └── index.en.md
+    ├── ffmpeg-screen-casts
+    │   └── index.en.md
+    ├── find-folder
+    │   └── index.en.md
+    ├── git-better-git-add
+    │   └── index.en.md
+    ├── git-log-grep
+    │   └── index.en.md
+    ├── git-move-branch
+    │   └── index.en.md
+    .
+    .
+```
+
+To start with I preformed the operation in question a single time to prove it works:
+
+```shell
+$ mv ./who-is-using-that-port/index.en.md ./who-is-using-that-port.en.md && rm -r ./who-is-using-that-port
+```
+
+Then I copy this command to the clipboard for later and use command history pull up a
+previous for loop command and switch the shell command entry external editing
+in vim mode, for me **\<C-x>\<C-e>**. As we are essentially writing a quick bash script in-line we need vim
+powers! While in vim if you need the file list a quick **:r !ls** does the trick.
+These little efficiencies like using command history are not just faster but make it so you
+don't have to remember the bash syntax.
+
+Resulting vim buffer with the for loop:
+
+```shell
+for x in \
+aws-s3-sync \
+ffmpeg-screen-casts \
+find-folder \
+git-better-git-add \
+git-log-grep \
+...
+git-move-branch \
+vim-window-resize ; do mv ./"$x"/index.en.md ./"$x".en.md && rm -r "$x" ; done
+```
+
+Resulting new file structure:
+
+```shell
+$ tree
+.
+└── snippets
+    ├── _index.en.md
+    ├── aws-cloud-front-inval.en.md
+    ├── aws-s3-sync.en.md
+    ├── ffmpeg-screen-casts.en.md
+    ├── find-folder.en.md
+    ├── git-better-git-add.en.md
+    ├── git-log-grep.en.md
+    ├── git-move-branch.en.md
+    .
+    .
+```
+
+Perfect, all files have been renamed properly and the empty directories deleted. This technique has
+lots of other applications besides moving and renaming files. Earlier this week while debugging api
+at work I dumped bunch of json responses into a file so I could search for translation key.
+
+```shell
+$ for x in \
+https://api.poeditor.com/v2/download/file/xxx \
+https://api.poeditor.com/v2/download/file/xxx \
+https://api.poeditor.com/v2/download/file/xxx \
+https://api.poeditor.com/v2/download/file/xxx \
+https://api.poeditor.com/v2/download/file/xxx \
+https://api.poeditor.com/v2/download/file/xxx \
+https://api.poeditor.com/v2/download/file/xxx \
+https://api.poeditor.com/v2/download/file/xxx \
+https://api.poeditor.com/v2/download/file/xxx \
+https://api.poeditor.com/v2/download/file/xxx ; do curl $x >> /tmp/translations.json; done
+```