add: cdpath-easily-navigate-directories

bash/cdpath-easily-navigate-directories-in-the-terminal.md

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+# CDPATH: Easily Navigate Directories in the Terminal
+
+The CDPATH environment variable lets you pre-configure frequently used directories so you can easily navigate into them from anywhere in your file system[^1].
+
+A `cd` search path works like your command search path `$PATH`. However, instead of finding commands, it finds the subdirectories. You can configure it with the shell variable `CDPATH`, and it has the same format as the `PATH` variable: a list of directories separated by colons.
+
+Set this variable in your `~/.zshconfig` or `~/.bashrc` file to include the directories you visit most frequently.
+
+```bash
+export CDPATH=$HOME:$HOME/software:$HOME/software/js:$HOME/software/web
+```
+Now, whenever you want to `cd` into a directory, the shell will look through all the above places in addition to the current directory.
+
+What’s more, the search is lightning fast. It looks only in parent directories that you specify and nothing else.
+
+For example, let’s say you have a `$HOME/software/blog` directory and you’ve configured the CDPATH to include the `$HOME/software` directory.
+
+Now, if you type `cd blog` from anywhere in the filesystem, the cd command will take you to the `$HOME/software/blog` directory, unless it finds another `blog` directory in another pre-configured path.
+
+> The order of `CDPATH` matters. If two directories in `$CDPATH` have a subdirectory named blog, the earlier parent wins.
+
+In the above example, `cd` will check the existence of the following directories in order, until it finds one or it fails.
+
+1. in the current directory
+
+2. `$HOME/software/blog`
+
+3. `$HOME/software/js/blog`
+
+4. `$HOME/software/web/blog`
+
+P.S. Don't overdo it. If you put too many directories with common names into CDPATH and `export` it, it might break your scripts.
+
+[source](https://learning.oreilly.com/library/view/efficient-linux-at/9781098113391/)
+
+[^1]: [`z`](https://github.com/rupa/z) does a great job of achieving the same outcome by tracking your most used directories, based on ['frecency'](https://web.archive.org/web/20210421120120/https://developer.mozilla.org/en-US/docs/Mozilla/Tech/Places/Frecency_algorithm). After  a  short  learning  phase, z will take you to the most 'frecent' directory that matches ALL of the regexes given on the command line, in order. Rather elegant, and I use it all the time.