UNIX for Dummies Questions & Answers

I'm having an issue with a problem
A problem with this backup script is that if you backup the same file twice, you may get a warning message because you're overwriting an existing file. You could suppress the warning message, but a better solution is to save a series of backups distinguished by numbers. The first time you type backup foo.c, it copies it to foo.c.1. Then you make some changes to foo.c and type backup foo.c again; the script notices that foo.c.1 is already there, so it copies foo.c to foo.c.2 instead. The third time, you get foo.c.3, and so on

Here is the code I have so far:

#!/bin/csh -f

file ($*)
set num=1

while (-e $file.$num)
@ num = $num +1

do
cp ${file} ${file}.$num

if anyone could fill in the gaps or tell me where I'm going wrong here.. it would be greatly appreciated

Moderators, please lock/delete this thread. It is an exact duplicate of this.