Command-line Flags under MacOS

There are two methods for passing command-line arguments to MrEd under MacOS:

• The first method is a strange extension of an old Unix hack. For this method, MrEd must be started with a single startup file (e.g., by dragging one file onto the MrEd application). The data fork of this file must begin with a pound sign followed by an exclamation point (#!). Starting with the next whitespace, the rest of the first line in the file is used as the command line for MrEd.

  There are several special parsing considerations for this ``command line'':

  • The first line of the file (containing the command line) must be less than 2048 characters wide.
  • No more than 32 command line arguments are allowed.
  • Unless the file starts with #!!, the name of the startup file is appended as an extra command line argument.
  • If %% is used as a command line argument, it is replaced with the name of the startup file.
  • If %: is used at the beginning of a command line argument, the leading % is replaced with the startup file's directory.
• The second method is to start MrEd with a special high-level event in place of the OpenApp or OpenDoc AppleEvent. This high-level event has the class 'PLT ' and the ID 'cmdl'; the content of the event is the command line string. No expansions are performed on the command line.

In both methods, parsing rules for command-line arguments are the same as in Unix's sh (after globbing, variable, and backquote expansion).

When MrEd is opened with multiple input files, or when a single input file's data fork does not start with #!, the command line is the sequence of complete file pathnames. (The order of the files is determined by the OpenDoc AppleEvent.)