#!/usr/bin/perl

warn "\n==normal case:\n";
print "running ls:\n";
system( "ls" );

open my $oldout, ">&STDOUT";  # "dup" the stdout filehandle
close STDOUT;

warn "\n==STDOUT closed:\n";
print "running ls a 2nd time\n";
system( "ls" );

open STDOUT, '>&', $oldout;  # restore the dup'ed filehandle to STDOUT

warn "\n==STDOUT reopened:\n";
print "running ls a 3rd time\n";
system( "ls" );