Something to note which wasn't mentioned here is that `cd` is not a binary executable, but instead a shell command. You won't find it anywhere in /bin, /sbin and so on. That's also why `sudo cd ` doesn't work, `sudo` will try to execute `cd` as root but it's not an executable so it won't find it. (tip: do `sudo -i` instead)
cd is a good example of something that has to be a built-in command, because it makes the shell itself do something (change its current working directory). Other commands in that category are umask, the job control ones (fg, bg, wait, ...), the ones setting variables (read, printf), and the control flow ones (if, while, break, return, exit, ...).
A lot of commands are also built-in for convenience but don't strictly need to be.
That sounds like a weird way to implement a built-in command (the IPC handler still needs to be built-in, so you didn't really remove it from the shell). And then if course that binary would be available globally but only work if you're using the shell it's built for...
You could hook up to the parent process with ptrace or the equivalent debugging API of your OS of choice and forcibly change the directory. Stackoverflow even has an implementation: https://unix.stackexchange.com/a/114262/81005
As that comment said, it’s there so utilities can use it for checking the return of “chdir()”. It’s at best a name conflict with a shell command with a well established past and use. At worst, it probably enables some bad code smells or outright malicious code.
We can use the `compgen -b` (`help cd` to get short help or `man bash-builtins` to read man pages) to list all internal bash commands. For example, we can use the `type -a cmd1` or `command -V cmd1` to see if `cmd1` is built-in or external binary.
Don’t forget “dirs -v”. I’ve tried to use Powershell a few times and always tap out because it doesn’t come with the dirs command. It’s so fundamental to my workflow a shell without it or without an easy way to implement it is a no go.
An executable of 'cd' wouldn't do anything useful, it could only change its own idea of working directory then exit, the shell or other executable that invoked it would be unchanged.
