> Let me clarify the idea. > If a filter recognizes '-' as a name for stdin, > then stdin can be one of the _multiple_ files being processed. > Filters that do not recognize '-' as a name, on the other hand, > only process stdin if it is the _only_ input.
I understand that - is convenient, but it's not strictly needed. If you need the standard input as one of several files (or as an explicit file argument), you can pass /dev/stdin.