Question about variables

Shell Programming and Scripting
1

What does this mean?

#!/bin/bash
BACKUPFILE=backup-$(date +%m-%d-%Y)
archive=${1:-$BACKUPFILE}
2

The variable archive gets set to $1 if it exists otherwise if get set to "backup-$(date +%m-%d-%Y) (e.g. "backup.10-29-2009")

3

i would suggest reading up on bash parameter substitution... It's comes in really handy if you have to do a lot of manipulation with a single variable otherwise you have to add on a bunch of test logic.

4

Your question(s) could easily be answered by searching the Internet with Google. Google is your friend :smiley:

Have a read of these links:

Shell expansion

Operations on variables

Regards

5

thanks:)