and I just want to evaluate whatever is there in the parameter

That might end in tears!

use strict;
use warnings;

my $param = shift;
eval $param;
die $@ if $@;
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Let's see some files.

$ perl spw848064 'system ls'
reallyImportant.data  spw848064
$
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You can see what's coming :-)

$ perl spw848064 'system qw{rm -f reallyImportant.data}'
$
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Oops!

<!--$ perl spw848064 'system ls'
spw848064
$
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It might be worth doing a little sanity checking before evaling willy-nilly.