panel 1: ls .. and cd .. refer to different folders if you cd to a symlinked folder

~/Dropbox -> ~/Library/CloudStorage/Dropbox

cd ~
cd Dropbox
ls ..
cd ..

• ls .. lists ~/Library/CloudStorage
• cd .. moves to ~

this is because ls is a program and cd is run by the shell.

The shell handles .. differently from other programs.

panel 2: ls ~/Dropbox will list the contents of the folder

this is annoying if you just want to look at its permissions, or where it links to

to fix this:

ls -d ~/Dropbox

panel 3: deleting a folder and recreating it with the exact same name makes everything weird

everything you do in the folder will fail with weird errors like:

$ touch newfile
touch: newfile: no such file
or directory

how to fix it:

cd .

panel 4: on Mac OS, these are not the same: cp -R a/ b and cp -R a b

• cp -R a/ b merges the contents of a into b
• cp -R a b copies the whole folder into b/a

panel 4: tip: cd - switches to the folder you were previously in

panel 5: notes on mv file.txt dest

• if dest is a file: renames file.txt
• if dest is a folder: moves file.txt to that folder