Editing Macintosh Programmer's Workshop (section)

==MPW Shell==
The MPW Shell featured [[Redirection (computing)|redirection of output]] to files, as well as to windows.  If a file was open, the output would go to the file and to the open window.  This redirection of output required significant patching out of the file system calls so that tools need not do anything special to inherit this feature: the MPW Shell did all of the work.

The MPW Shell command language was based on the Unix [[C shell|csh]] language, but was extended to support the main features of the Macintosh GUI.  It had simple commands to create menus, dialogs (prompts), and new shell windows.  The cursor could be controlled, and MPW scripts or tools could easily be attached to a menu item.  Command key shortcuts could be specified.  Window size and location could be controlled.  These features were popular in commercial production environments, where complicated build and packaging processes were all controlled by elaborate scripts.

The shell had some important differences from its Unix counterparts. For instance, the classic Mac OS had nothing comparable to Unix [[Fork (operating system)|fork()]], so MPW tools were effectively called as subroutines of the shell; only one could be running at any one time, and tools could not themselves run other tools. These limitations were the inspiration for the MacRelix project, a "Unix-like system" for classic Mac OS.<ref>{{cite web|url=http://www.metamage.com/text/relix/origins.html|title=MacRelix Origins}}</ref>

===Look and feel===
Functionally, a ''worksheet'' is a cross between a [[text editor]] document and an [[xterm]] window. Each worksheet window is persistently bound to a file. The user may type anything anywhere in the window, including commands, which can be executed via the keyboard's Enter key; command output appears at the insertion point. Unlike an xterm window, an MPW worksheet is always in visual editing mode and can be freely reorganized by its user. Hence a worksheet can be purely a command script or purely a text document or a mixture of the two&mdash;an integrated document describing the history, maintenance procedures and test results of a software project. The commercial [[BBEdit]] text editor retains a feature it calls "shell worksheets" on Mac OS X. The [[Emacs]] text editor provides shell buffers, a similar feature that works across platforms.