An easy one....

Sonny · 03-07-2002, 02:46 PM

Hi Guys,

Doing a little bash scripting and came across a little mystery (well.. a mystery for me anyways). When I type
echo $PWD I get the current working directory echoed to console. How is $PWD being initialized with the current directory? Is it a variable that is maintained by the shell? And if so, where can I find reference to all of these shell variables?

Sonny.

entm · 03-07-2002, 03:33 PM

You can get a list of all your current shell variables with the command:

env

The command:

pwd

means 'print working directory'. I'm not sure what throwing a $ in front of the command is actually doing, if it is doing anything at all.

Sonny · 03-07-2002, 04:12 PM

Thanks entm,

I also discovered that PWD is a special shell variable maintaned by bash to always be my current working directory.

In addition, the following are special variables:

PWD - always the current directory
RANDOM - a different number every time you access it
$$ - the current process id (of the script, not the user's shell)
PPID - the "parent process"s ID. (BUT NOT ALWAYS, FOR FUNCTIONS)
$? - exit status of last command run by the script
PS1 - your "prompt". "PS1='$PWD:> '" is interesting.

Sonny.