How do I make it work for patterns such as "a*sample*.cgi" (the string to match is within the quotes)?

First of all, are you sure that the regular expression you give in your example is what you want to get? (0 or more "a"s followed by "sampl" and 0 or more "e"s, then, any character followed by "cgi"

Although I agree with the previous suggestions of using the glob function instead of your own grep, your script should work as well.

I guess that your problem is due to a premature expansion of your regular expression: if you don't enclose the regexp in quotes it will be expanded by the shell before passing the arguments to the script:

Suppose that you have a directory like this:

$ ls -1 /tmp/test/
other.txt
test10.txt
test1.txt
test2.txt
test3.txt
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If you name your script "find_files.pl" and you call it with:

$ perl find_files.pl test*.txt
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then, the shell will try to expand test*.txt and will pass the result of this expansion to the script. If you don't want this, you must put single quotes around it and provide the script with a valid perl regular expression like in:

$ perl find_files.pl 'test.*\.txt'
wildcard is test.*\.txt
/tmp/test/test10.txt
/tmp/test/test3.txt
/tmp/test/test2.txt
/tmp/test/test1.txt
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citromatik