This post is just some curious geek stuff about Linux.
pwd is a shell built-in command that shows you the working directory. A good part of the built-in commands also have an external program that, in theory, behaves just like the built-in one.
Well, that’s the theory; in practice some external commands behave differently than the respective built-in. This post shows the example of the pwd command. When I type pwd here, the return is /home/dmelo.
Now comes the weird demo. Create a symbolic link to /tmp in your home directory and go to your new link.
dmelo@merov:~$ ln -s /tmp/ tmp
dmelo@merov:~$ cd tmp
Now, run two commands: the first is pwd and the second, /bin/pwd. You will see something like this:
dmelo@merov:~/tmp$ pwd
/home/dmelo/tmp
dmelo@merov:~/tmp$ /bin/pwd
/tmp
The thing is that the pwd built-in command does not care about where your symbolic link is pointing to. On the other hand, the program /bin/pwd cares. /bin/pwd replaces the symbolic link with the directory it points to. As the built-in commands have precedence over external commands, when you just type pwd it uses the built-in version of pwd.
See you in the next geek creepy story about Linux :D