Why should you run cd . before doing anything?

In this compilation of sysadmin horrors, one of the authors writes, as a rule of thumb:

Always do a cd . before doing anything.

Why would you want to do that?

You don't.

At least not just like that. The preceding line in the quoted document is of importance:

• Set up your prompt to do a pwd everytime you cd.
• Always do a cd . before doing anything.

This way, you as the operator verify your current working dir before doing anything of importance, as it's printed out with each change. cd . doesn't make any sense otherwise.

This "verification" is a good thing, and you should adapt a form of it. A more (IMHO) common variation of this theme is to always print out the working dir at the prompt.

If the current working directory of your shell is removed, it is possible to lose data.

For example,

$ pwd
/home/user/test
$ rmdir /home/user/test
$ pwd
/home/user/test
$ some_command | tee command.log
tee: command.log: No such file or directory
<long output>

The output of some_command was not written to the disk.

Typing cd . before running a command would reveal the problem.

$ pwd
/home/user/test
$ rmdir /home/user/test
$ cd .
$ pwd
.

If the current working directory directory was removed and re-created, typing cd . would "refresh" the reference to that directory.

$ ls
foo bar ljz
$ pwd
/home/user/test
$ rmdir /home/user/test
$ mkdir /home/user/test
$ pwd
/home/user/test
$ ls
$ cd .
$ ls 
foo bar ljz

I think it's more important to show your current directory.

On every linux server, I modify the prompt in /etc/bashrc by changing "W" to "w".

 [ "$PS1" = "\\s-\\v\\\$ " ] && PS1="[\u@\h \W]\\$ "

to

 [ "$PS1" = "\\s-\\v\\\$ " ] && PS1="[\u@\h \w]\\$ "

The effect of this is:

[root@xt include]#

versus

[root@xt /usr/src/spl-0.6.1/include]#