Hi,

There's only one thing really wrong: you shouldn't use backticks with open. Backticks are for when you need all output in a scalar or array, using $list = `ls` or @list = `ls`
I think the "ls $file|" really had to be "ls $mask|".

Calling an external program for simple things like this is considered bad style. Perl has its own ways of listing files: glob, with which you can shell-like globs (* and ? wildcards) and opendir/readdir/closedir.

And another thing about style: most people use ALLCAPS for their file handle names, and all lowercased characters for normal identifiers. These "rules" are described in perlstyle.

sub fill_list {
 my ($mask, $file) = @_;
  # somewhat more efficient than two shifts
 open (LIST, '>', $file) or die "Couldn't open $file: $!";
 
 for (glob($mask)){
  print LIST "$_\n";
 }

 close LIST;
}
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Instead of the for-loop, it can be done using a single print statement:

 print LIST map("$_\n", glob($mask));
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Please note some people consider glob() to be as evil as calling an external program, and some computers have bad libraries, which can cause some trouble when there are file names with spaces in them. (These bad libraries list the two files "File name" and "Hello, World!" as if it were four files: "File", "name", "Hello,", "World!").

2;0 juerd@ouranos:~$ perl -e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$
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