This is a nifty idea -- though I think jeffa's comment is dead-on. The only other point, not a major one: if the input list is long and you're going to execute some shell command on lots of items in rapid succession, you might save some overhead this way:

open( SH, "| /bin/sh" );
...
sub execute {
  my ($com, $columns) = @_;
  # substitute the value from the appropriate column for \0, \1, etc.
  $com =~ s/\\(\d+)\;?/$columns->[$1]/g;
  print SH "$com\n";
}
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This can make a difference when the command line being run involves shell metacharacters (e.g. pipes, redirection, logic operators, etc), because when you pass something like that to "system()", it invokes a new shell to run it. For simpler command lines, printing to SH simply means that perl doesn't do "fork;execvp" (which is what the shell would do anyway, I suppose). For a demonstration, look at (my shameless plug for) shloop -- execute shell command on a list.