Like this perhaps ?

#!perl
use strict;
use Hash::Util 'lock_keys';
use Data::Dumper ;

# valid
my $cmd = ops_new_cmd({ name=>1, user=>2, host=>3});
print Dumper $cmd;

# not valid
$cmd = ops_new_cmd({ name=>1, user=>2, hostt=>3});

sub ops_new_cmd {
  my ($init_hash) = @_;
  my @valid = qw( name user host key command status 
                  ssh_retcode ssh_retmsg   output
                  std_err     cmd_ret_code cmd_ret_msg);              
+  
  lock_keys(my %new_cmd,@valid);
  %new_cmd = %$init_hash;
  return \%new_cmd;
}
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