UNIX for Dummies Questions & Answers

Searched forums and google with no luck. I simply want to know what ./ does when placed in front of a command. Why and when is it needed? Thanks.

The ./ means that you want the system to search for that command in the current directory

./ says look in your current directory. This is needed if your $HOME directory is not set in your search PATH.

It has nothing at all to do with $HOME not being in $PATH, well unless the script is in $HOME.

UNIX uses an environment variable $PATH as a colon delimited list to define directories to be searched for commands entered into the shell. If $PATH is st to /usr/bin only, when you type ls, it looks in /usr/bin for something called ls, then tries to execute it. If ls is not in /usr/bin, it returns a file not found error.

Typically the path is set to a limited number of directories to make searches quick. If you want to exectute something not in a directory in $PATH, you have to specify the path to it. You can do this explicitely from root (example: /usr/bin/ls ), relative to where you are ( cd / ; usr/bin/ls ), or if it is in the directory you are in, with ./ ( cd /usr/bin ; ./ls ).

You may also use ./ if you want to use a specific version of a program. Say there are two ps commands, one in /usr/bin, the other in /usr/ucb/bin/ps. You want to use the latter, you can type the full path, or cd to /usr/ucb/bin, then run ./ps

Yeah that was sort of a dumb response on my part. Sorry, knee jerk reaction to the question here at work of why users cannot execute scripts in their home directories from other dirs. They need to have HOME in their search path. 98_1LE is right.

Thank you all very much. It's a question I've had for over a year and finally got around to asking. 98, thanks for the detailed explanation.

You may find this article/tutorial useful.

Cheers
ZB