Simply add your parameters to the command prompt, separated by space, without any placeholder for filenames. 
To construct commands like `ls -l <file>`, just enter `ls -l`. 

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**OR**: the interface supports the placeholders `*` and `?`. 
Where `?` means call command with one marked file only, in a loop; 
and `*` means call with all marked files. 
Read more at [masteringemacs.org](https://www.masteringemacs.org/article/dired-shell-commands-find-xargs-replacement)

Example: (`ls` would be your `<command>` **and** `-l` would be your `<additional-arguments>`). 
You could enter `ls * -l` as command for example to run `ls <files> -l` once (with all marked files at once). 
Or you could enter `ls ? -l` to run `ls <file> -l` for every single file.

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*Edit:* dired-do-shell-command help string: 

> Signature 
> (dired-do-shell-command COMMAND &optional ARG FILE-LIST)
> 
> Documentation 
> ... 
> If there is a * in COMMAND, surrounded by
> whitespace, this runs COMMAND just once with the entire file list
> substituted there.
> 
> If there is no *, but there is a ? in COMMAND, surrounded by
> whitespace, this runs COMMAND on each file individually with the file
> name substituted for ?.