You need to take a look at your process table (untested):

#!/usr/bin/env perl

use strict;
use warnings;
use Proc::ProcessTable;
use feature qw(say);

say grep {/emacs/i} 
    map { $_->cmndline } @{ Proc::ProcessTable->new->table };

__END__
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See also Proc::ProcessTable and Better way to search in the process table?.

Regards, Karl