Classic Shell Scripting

Unix Tools for Windows Systems

Many programmers who got their initial experience on Unix systems and subsequently crossed over into the PC world wished for a nice Unix-like environment (especially when faced with the horrors of the MS-DOS command line!), so it's not surprising that several Unix shell-style interfaces to small-computer operating systems have appeared.

In the past several years, we've seen not just shell clones, but also entire Unix environments. Two of them use bash and ksh93. Another provides its own shell reimplementation. This section describes each environment in turn (in alphabetical order), along with contact and Internet download information.

Cygwin

Cygnus Consulting (now Red Hat) created the cygwin environment. First creating cgywin.dll, a shared library that provides Unix system call emulation, the company ported a large number of GNU utilities to various versions of Microsoft Windows. The emulation includes TCP/IP networking with the Berkeley socket API. The greatest functionality comes under Windows/NT, Windows 2000, and Windows XP, although the environment can and does work under Windows 95/98/ME, as well.

The cygwin environment uses bash for its shell, GCC for its C compiler, and the rest of the GNU utilities for its Unix toolset. A sophisticated mount command provides a mapping of the Windows C:\path notation to Unix filenames.

The starting point for the cygwin project is http://www.cygwin.com/. The first thing to download is an installer program. Upon running it, you choose what additional packages you wish to install. Installation is entirely Internet-based; there are no official cygwin CDs, at least not from the project maintainers.

DJGPP

The DJGPP suite provides 32-bit GNU tools for the MS-DOS environment. To quote the web page:

DJGPP is a complete 32-bit C/C++ development system for Intel 80386 (and higher) PCs running MS-DOS. It includes ports of many GNU development utilities. The development tools require an 80386 or newer computer to run, as do the programs they produce. In most cases, the programs it produces can be sold commercially without license or royalties.

The name comes from the initials of D.J. Delorie, who ported the GNU C++ compiler, g++, to MS-DOS, and the text initials of g++, GPP. It grew into essentially a full Unix environment on top of MS-DOS, with all the GNU tools and bash as its shell. Unlike cygwin or UWIN (see further on), you don't need a version of Windows, just a full 32-bit processor and MS-DOS. (Although, of course, you can use DJGPP from within a Windows MS-DOS window.) The web site is http://www.delorie.com/djgpp/.

MKS Toolkit

Perhaps the most established Unix environment for the PC world is the MKS Toolkit from Mortice Kern Systems:

MKS Canada - Corporate Headquarters

410 Albert Street

Waterloo, ON

Canada N2L 3V3

1-519-884-2251

1-519-884-8861 (FAX)

1-800-265-2797 (Sales)

http://www.mks.com/

The MKS Toolkit comes in various versions, depending on the development environment and the number of developers who will be using it. It includes a shell that is POSIX-compliant, along with just about all the features of the 1988 Korn shell, as well as more than 300 utilities, such as awk, perl, vi, make, and so on. The MKS library supports more than 1500 Unix APIs, making it extremely complete and easing porting to the Windows environment.

AT&T UWIN

The UWIN package is a project by David Korn and his colleagues to make a Unix environment available under Microsoft Windows. It is similar in structure to cygwin, discussed earlier. A shared library, posix.dll, provides emulation of the Unix system call APIs. The system call emulation is quite complete. An interesting twist is that the Windows registry can be accessed as a filesystem under /reg. On top of the Unix API emulation, ksh93 and more than 200 Unix utilities (or rather, reimplementations) have been compiled and run. The UWIN environment relies on the native Microsoft Visual C/C++ compiler, although the GNU development tools are available for download and use with UWIN.

http://www.research.att.com/sw/tools/uwin/ is the web page for the project. It describes what is available, with links for downloading binaries, as well as information on commercial licensing of the UWIN package. Also included are links to various papers on UWIN, additional useful software, and links to other, similar packages.

The most notable advantage to the UWIN package is that its shell is the authentic ksh93. Thus, compatibility with the Unix version of ksh93 isn't an issue.