Re: shell-command-on-region

[Richard Stallman]

    - shell-command looks like it's in the same class since it does a fair bit
      of extra stuff that is rarely useful when called as an Elisp function
      rather than an Emacs command.  It also has the side effect of passing the
      command to `sh' which is great when that's what you need, but otherwise
      has the severe disadvantage that you have to be extra careful to correctly
      quote all your arguments 

When what you want to do is call a program with certain arguments, it
is generally better to use call-process and avoid the shell.  However,
the feature of shell-command-on-region that it puts the errors in a
separate buffer for you might make it useful.  In using call-process
one would have to do that by hand.