[owner rwx] "They can read, write, and execute things inside that directory." None of that is correct. It means the user (r) can read the list of names and the types of the objects in that directory; (w) can create, rename, and delete objects in that directory; (x) can read the metadata (owner, group, permissions, timestamps) and can change into that directory (which is the (only) requirement for accessing any content). The permissions of a file in that directory determine if you can read, write, and/or execute it (assuming you can reach it (x)). Given that the directory has 750, noone except the owner and the group members can read any of those 644 files. [sudo !!] In general it is better to use the upward arrow key to get the last command line back for editing and prepend it with sudo. [alias] Talking about aliases it would have made a lot of sense to mention that everyone can easily create such aliases for themselves by adding the alias definitions to .bashrc or a dedicated aliases file. [ACL] In a 16min video about filesystem permissions I would have expected that ACL and overriding mount options (ro,noexec) are not explained in detail but at least mentioned.
[owner rwx] "They can read, write, and execute things inside that directory." None of that is correct. It means the user (r) can read the list of names and the types of the objects in that directory; (w) can create, rename, and delete objects in that directory; (x) can read the metadata (owner, group, permissions, timestamps) and can change into that directory (which is the (only) requirement for accessing any content). The permissions of a file in that directory determine if you can read, write, and/or execute it (assuming you can reach it (x)). Given that the directory has 750, noone except the owner and the group members can read any of those 644 files.
[sudo !!] In general it is better to use the upward arrow key to get the last command line back for editing and prepend it with sudo.
[alias] Talking about aliases it would have made a lot of sense to mention that everyone can easily create such aliases for themselves by adding the alias definitions to .bashrc or a dedicated aliases file.
[ACL] In a 16min video about filesystem permissions I would have expected that ACL and overriding mount options (ro,noexec) are not explained in detail but at least mentioned.