On our server we have a certain directory, say /storage, that contains many large files. They are all compressed (gzip). Many of our users are not computer-savvy, and so when one of these files is needed, they will copy it to their own directory. Consequently, we have multiple terabytes of duplicate data. I'd like to enforce an alias whereby if someone tries to use cp on a file from /storage, they will instead create a symbolic link. My idea was something like:

alias cp='cp.storage'

File cp.storage:

#!/bin/sh

truePath=$(readlink -f "$1")

if [ $(expr match "$truePath" "/storage") -gt 0 ]
then

gzip -rd "$1" 2> /dev/null
ln -s "$truePath" "$2"

else

/bin/cp "$1" "$2"

fi

The conditional checks whether the file being copied begins with "/storage".

The problem with this is that if someone wanted to use cp with any options on a file not in /storage, those options would be obliterated. Can someone guide me as to a good way to accomplish this? Either a way to get the options from cp into cp.storage, or another approach not using alias this way. Everyone will be using bash.

Here is a way to reference all of the arguments passed to a bash script.
http://www.tldp.org/LDP/abs/html/int...s.html#ARGLIST

So you would probably want to do something like
I believe that will pass all of the original arguments to the cp command.

Be sure to define the alias in an export statement so that the alias will be defined in child processes.

Your code has a bit of a problem though. If it is called with typical parameters for cp your code chokes.

Actually I edited your code for testing as follows.
I found that it won't work for
It looks like you've got a bit of work ahead of you.

Well, I didn't read the manpage of cp closely enough. There's an option -s (--symbolic-link) to create symbolic links instead of copying. Thanks for the tip about $@ -- that's what I needed! I have a script that should work now. (By the way, I think the reason your example "cp /storage/hammer ." didn't work is because the file didn't exist, so readlink returned "", which doesn't match "/storage". This shouldn't cause any problems, as far as I can see. If a source file doesn't exist, then regular cp can handle that. If the target doesn't exist... well, users aren't allowed to write to /storage.)

I scan all of the arguments to see if they are existing files. If so, I see if they begin with "/storage". If they do, then I set a variable "link" to 1. After scanning the arguments, if link is equal to 1, then I use cp and add the symbolic link option -s. Otherwise, I go ahead with the copy.

Thanks for your help. I'm putting this up in case anyone has a similar problem they want to tackle. Let me know if you see any issues with what I came up with.