On 10/14/09 Wed Oct 14, 2009 3:38 PM, "Felix Dorner" <felix...@web.de>
scribbled:
> Hi,
>
> I did the best book purchase in years: The Perl Cookbook. They have an
> example that seems to come right from Larry Wall himself. And I don't
> get it. I can use it but I don't understand why it works with wildcards.
>
> $op = shift or die "Usage: rename expr [files]\n";
> chomp (@ARGV = <STDIN>) unless @ARGV;
> for(@ARGV) {
> $was = $_;
> eval $op;
> die $@ if $@;
> rename ($was, $_) unless $was eq $_;
> }
>
>
> #rename.pl s/\.orig// httpd.conf.orig
>
> will rename httpd.conf.orig to httpd.conf. But it also works with wildcards:
>
> #rename.pl s/\.orig// *
>
> will chop .orig from all files in the current directory.
> So it assigns <STDIN> to @ARGV. But <STDIN> is just a * right? Does the
> shell expand this, or perl? Any comments/detailed explanations welcome.
The shell will expand the '*' to all files in the current directory and
place the file names in the @ARGV array, with the regular expression as the
first element $ARGV[0]. The RE is shifted out of the @ARGV array, leaving
the files names to be processed by the for loop.
If there are no arguments left in @ARGV after the RE has been removed, then
standard input will be read to supply a list of file names. Therefore, you
can pipe the results of some command that generates file names, such as ls
or find, to rename:
ls *.dat | rename s/dat$/data/
--
Jim Gibson
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