I was surprised to see `$()` missing from this (otherwise quite extensive) list. There are a few commands listed which employ it, but it absolutely deserves its own entry.

That and `readlink -f` to get the absolute path of a file. (Doesn't work on MacOS; the only substitute I've found is to install `greadlink`.)

And `cp -a`, which is like `cp -r`, but it leaves permissions intact - meaning that you can prepend `sudo` without the hassle of changing the ownership back.

I never see `lndir` on these lists either. It makes a copy of a directory, but all of the non-directory files in the target are replaced with symlinks back to the source while directories are preserved as-is. Meaning that when you `cd` into it, you are actually landing in a copied structure of the source directory instead of the source directory itself, as would be the case if you just symlinked the source folder.

Once inside, any file you want to modify without affecting the original just needs you to create the symlink into a file, which you can do with `sed -i '' $symlink`. There you have it: effectively a copy of your original directory, with only the modified files actually taking up space (loosely speaking).

Looks like I have a few pull requests to submit.