Perl uses /bin/sh. It would be useless if the syntax of the command had to vary based on what shell a user used on a particular day.

You could always run csh from sh.

use String::ShellQuote qw( shell_quote );
my $cmd = shell_quote('csh', '-c', 'wget http://... |& tee ...');
my $result = `$cmd`;
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Or avoid you can use the multi-arg open-pipe syntax to avoid sh and run csh directly.

my $cmd = 'wget http://... |& tee ...';
open(my $pipe, '-|', '/bin/csh', '-c', $cmd) or die $!;
my $result; { local $/; $result = <$pipe>; }
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Or you can adjust for sh.

my $cmd = 'wget http://... 2>&1 | tee ...';
my $result = `$cmd`;
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